1,721,225 research outputs found
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Do Functional Traits Relate Metabolic Scaling Theory to Observed Growth Rate?
No full textTo model plant growth, ecologists have integrated metabolism into allometric equations, most notoriously known in the West Brown Enquist model, which is an extension of the all-inclusive Metabolic Scaling Theory (MST) (West et al. 1999). This formula takes form of the power function Ṁ = βMᶿ, where β is the allometric normalization constant, M is total biomass, θ is a scaling exponent, and Ṁ is the metabolic and thus growth rate of the organism. Kleiber's law assumes that M should scale to the ¾ power, and the WBE model supports this claim. To test this, we measured the growth rate of 64 trees on Mount Bigelow, Arizona and showed that Ṁ scales in proportion to M. While there are many external factors that influence plant growth, we focused on modeling two types of functional traits: leaf-based and hydraulic-based. Our results show that the theoretical Ṁ from both equations are significantly different than 1, and we conclude that the WBE model may not include all variables relating to plant growth
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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Adaptive Diversification of Interaction Networks
No full textUnderstanding the processes responsible for gradients in biodiversity is a central goal of ecological research. In order to elucidate the processes responsible for community assembly and structure, it is useful to adopt a functional trait approach to community ecology. This is because species names provide little information regarding how constituent species interact. In addition, assembly rules based on species names are likely to become intractably complex with increasing species richness but rules based on traits can provide simple, broadly applicable. In turn, generality is gained by emphasizing functional traits. Here I first build from a previously published model that merged metabolic theory with a model of community evolution and assembly to derive a general assembly rule based on a continuous functional trait and compare this rule with a broad suite of empirical data (Chapter 1). However, linking metabolism to macroevolutionary rates and patterns has thus far been limited to non-ecological, static models. These models are not inconsistent with empirical data, but are relatively limited in their predictive ability (Chapter 2). I thus next develop a fully dynamic `metabolic theory of biodiversity' (MTB) that explicitly implements the qualitative framework proposed in Allen et al. (2007). With this model I examine the influence of temperature dependent mutation rate on speciation rate, extinction rate and species richness (Chapter 2). The model predicts a variable influence of temperature, but the processes responsible for this variation are not immediately clear. I subsequently conduct a detailed analysis elucidating the key processes that allow/constrain a strong influence of temperature dependent mutation rate on species richness (Chapter 3). In addition to mutation rate, temperature-dependent metabolism can influence ecological (feeding and mortality) and ecosystem (e.g. decomposition and in turn nutrient supply) rates. As such, I extend the model developed in chapters 1-3 to incorporate these additional temperature dependencies and derive predictions for the influence of temperature over species richness (Chapter 4)
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The Impacts of Environmental Change on Plant and Microbial Communities: A Turf Transplant Experiment in the Colorado Rocky Mountains
No full textClimate change is rapidly altering temperature and moisture regimes, reshaping species distributions, interactions, and ecosystem processes worldwide. High elevation mountain ecosystems are especially vulnerable due to accelerated climate change and limited opportunities for upslope range expansion, particularly as low elevation competitors move in. Responses to climate change are driven by a complex interplay of direct climatic effects and indirect species interactions. As a result, predicting how communities and ecosystems will change remains challenging, especially across biological scales.To address this, I established a reciprocal whole-community turf transplant experiment in the Colorado Rocky Mountains, relocating intact plant and soil communities across an elevational gradient characterized predominantly by shifts in temperature and moisture. This design allowed me to assess how community composition, flowering phenology, functional traits, and ecosystem functioning respond to environmental change. By transplanting both up and down elevation I tested for asymmetries in ecological sensitivity to climate shifts. Turfs transplanted downhill and exposed to a warmer environment had rapid, directional shifts in community composition, which were stronger in soil bacteria/archaea and weaker in plants and soil fungi. In contrast, turfs transplanted uphill and exposed to a cooler environment had slower, weaker, and more variable changes in community composition, with limited turnover. These asymmetrical responses suggest that upslope colonization by low-elevation species is more likely than downslope persistence, increasing the vulnerability of high-elevation communities to novel competitors and altered interactions. Flowering phenology shifted rapidly with both uphill and downhill transplantation, suggestive of strong plastic responses to both warming and cooling that mirrored natural elevational patterns. Community-level flowering and production converged with the destination sites within five years, despite differences in species composition. However, phenological shifts were only weakly associated with reproductive output and unrelated to species dominance, suggesting that timing differences are consistent responses to climate, but are poor predictors of broader ecological outcomes. Plant functional traits also shifted rapidly under warmer conditions, changing from traits associated with fast growth and resource use to traits linked to resource conservation and survival, similar to those found in the lower elevation, warm-adapted communities. In contrast, cooling led to slower and more inconsistent changes. These shifts were driven primarily by plasticity and, to a lesser extent, changes in species dominance. Notably, carbon and water fluxes increased under warming despite more conservative trait profiles, which suggests context-dependent links between local conditions, traits, and function. In summary, transplantation to warmer sites drove rapid reassembly of high elevation communities and altered ecosystem functioning, while transplantation to cooler sites overall led to slower, less consistent responses. These asymmetries indicate a heightened vulnerability of high elevation ecosystems to climate change, and the potential for upslope establishment of lower elevation species. While some community responses shifted predictably, others were context-dependent, indicating the complexity of ecosystem responses to environmental change. This dissertation reveals that complexity by empirically demonstrating the range of ecological responses to environmental change and exploring the mechanisms driving divergence. Although many ecological models and management plans depend on generalizable, predictable patterns, this work shows that in subalpine ecosystems, responses are often nonlinear, variable, and shaped by local context. In a time of urgent environmental decision-making, understanding this ecological complexity is essential for building informed strategies for a changing climate
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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