1,721,016 research outputs found
Modeling Aboveground–Belowground Interactions
No full textModels are powerful tools to capture the complexity of aboveground–belowground interactions in community ecology. Three general model aims can be distinguished: description, explanation, and prediction. These aims are covered by different model types such as conceptual models, graphical models, statistical models, functional–structural models, process-based models, reaction–diffusion models, cellular automaton models, and individual- or agent-based models. The available models of aboveground–belowground interactions always include interactions between root and shoot, and sometimes also trophic, competitive, facilitative, or mutualistic interactions. However, only very few of the existing aboveground–belowground models are community models that incorporate more than three species and more than one type of interaction. Furthermore, spatial relationships are rarely explicitly addressed. Thus, future approaches should (1) improve, simplify, and update current models, (2) extend current models to include more different interaction types and spatial relationships where this is justified by the model question, and (3) employ new modeling techniques such as game theoretical methods or Bayesian network models. Guidelines for model building are given based on the modeling cycle from question through concept, structure, and implementation to analysis and documentation. Close cooperation between empiricists and modelers will promote the success of future models of aboveground–belowground interactions
Current Knowledge and Future Challenges of Aboveground and Belowground Community Ecology
No full textThis final chapter briefly summarizes main points clarified by the preceding chapters to capture what we have learned and then highlight key issues for new challenges for the research field of aboveground–belowground community ecology. The reviews and syntheses covered in this book highlight several key issues for exciting challenges in promoting future research in this field. Specifically, these challenges involve (1) strengthening the evolutionary perspective, (2) scaling-up to community and ecosystem level, and (3) developing applied solutions for global problems. These critical issues, which previous studies have little considered, will undoubtedly enhance the perspectives for further development of the research field of aboveground–belowground community ecology
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Effects of interaction between arbuscular mycorrhizal fungi, rhizobacteria, soil phosphorus and plant cytokinin content on tobacco growth
No full textMestrado em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaA rizosfera é uma zona importante em termos de actividade e diversidade microbiana, onde
ocorrem associações benéficas entre plantas e microorganismos, e é fundamental na produção
agrícola. Ao proliferarem num meio complexo e heterogéneo como o solo, as raízes desenvolvem-se de
forma estruturada, mas flexível, por forma a optimizar suas funções. Factores endógenos, como
fisiologia e genética da planta, bem como factores exógenos abióticos e bióticos são elementos
determinantes. Neste estudo proponho testar a hipótese de que os efeitos dos microorganismos do solo
sobre o crescimento da planta estão associados a efeitos sobre a morfologia radicular e dependentes
dos níveis endógenos de fitohormonas e disponibilidade de nutrientes no solo. Uma
experiência factorial foi instalada na estufa, com a presença ou ausência de Glomus
intraradices ou Pseudomonas fluorescens, com dois regimes de fertilização de fósforo, e com a linhagem
selvagem de tabaco (Nicotiana tabacum) ou a transgénica 35S:CKX2 com teor de citoquinina reduzido.
Os efeitos dos microorganismos sobre a biomassa alternaram entre o negativo, neutro ou positivo,
dependendo da linhagem, do regime de fertilização e a presença de microorganismos, e explicam-se
parcialmente com alterações na morfologia da raiz. A micorrização aumentou na linhagem 35S:CKX2 ou
em presença de P. fluorescens-------------------------------------------------ABSTRACT - The rhizosphere is an important zone for microbial activity and diversity, where several beneficial
associations between roots and microorganism occur, and is fundamental in terms of defining terrestrial
food production. When growing in a complex and heterogeneous medium such as soil, roots develop in
a structured but flexible manner to optimize their functions. Endogenous factor, such as plant
physiology and genetics, as well as abiotic and biotic exogenous factors are important determinants. In
the present study I hypothesized that the effects of soil microorganisms on root morphology are
associated with plant growth and differ depending on endogenous phytohormone levels and soil
nutrient availability. A full factorial experiment was set up in the greenhouse, with presence or absence
of Glomus intraradices or Pseudomonas fluorescens, with two phosphorus amendments, and with the
tobacco wild type (Nicotiana tabacum) or the 35S:CKX2 transgenic line with reduced cytokinin content.
The effects of microorganisms on plant biomass changed from negative to neutral and positive
depending on plant type, phosphorus amendment and microorganism presence, and are partially
explained by alteration on root morphology. Mycorrhization was enhanced in the 35S:CKX2 mutant or in
presence of P. fluorescensN/
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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