1,720,955 research outputs found
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
Utilizing dendrochronology to investigate multiscale drivers of conifer growth in the Pacific Northwest
No full textConifers dominate temperate and boreal forests around the world and many species are economically important for structural timber production. They are also adapted to extreme climatatic conditions, such as drought and cold temperatures. Numerous conifer species occur within the Pacific Northwest United States (PNW) including firs, hemlocks, cedars, larches, and pines. The diversity of hydrologic and geographic variables across the PNW creates distinctive localized climates with differing limiting factors on conifer growth, such as temperature, moisture, and nutrient availability. Dendrochronology, or tree-ring dating, is a multidisciplinary methodology that utilizes annual tree ring widths to investigate environmental conditions influencing trees or stands throughout their life. A substantial amount of information is known about tree-growth responses to climate and stand dynamics. However, investigations into interacting silvicultural and climatological influences, as well as spatial variability of growth relationships, may inform future management and dendrochronological techniques. The first three chapters of this dissertation utilize dendrochronology to investigate multiple drivers of species-specific tree growth. The first chapter investigates the impacts of density reductions, via different thinning intensities, on tree growth in moist mixed coniferous forests in northern Idaho, USA. Species that respond rapidly to available sunlight and/or nutrients, like western larch and western redcedar, show the greatest growth increases following thinning. The less consistent responses to thinning by western hemlock and grand fir were likely due to their autecological characteristics and inherent lack of responses to greater growing space. Findings from Chapter 1 align with past thinning experiments and found that thinning is an effective tool for increasing growth in most species. However, if the objectives are to favor injury-prone and less competitive species like western hemlock and grand fir, precautions must be taken during and after treatment to limit tree damage that could produce undesired responses. Chapter 2 presents the temporal variability of growth-drought relationships for the same species from Chapter 1, and how that relationship is influenced by thinning. The four species in this study, western larch, grand fir, western redcedar, and western hemlock, show a wide range of responses to drought depending on timing of drought, length of drought, intensity of drought, and forest stand density. Findings indicate that length and season of drought, species-specific drought tolerance, and stage of stand development, influence growth-drought responses. Drought sensitivity often involves trade-offs among other limiting factors like direct competition for resources. Moreover, trees growing in moist forests may not be as highly susceptible to droughts as those in dry forests. Therefore, it is suggested that stands be managed as complex adaptive systems by prioritizing species, age, and structural diversity. Results from Chapter 1 and Chapter 2 demonstrate that strip clearcutting in moist forest results in diverse conifer species composition and structure that can be further managed to create complexity through mid-rotation thinning. Chapter 3 focused at a larger spatial scale (e.g., greater PNW) to examine the effects of geographical factors on flow-growth relationships of four different conifer species. Streamflow correlated negatively with subalpine fir and mountain hemlock growth, species commonly found at cool, moist, high elevation sites, indicating that they are likely more sensitive to severe environmental variation like those experienced with climate change. Drier-site species, Douglas-fir and ponderosa pine were mostly positively correlated with flow, though a few had significant negative correlations, indicating that they are species with high adaptive capacity. Results help simplify planning for field collections and strengthen methodologies for future streamflow reconstructions by supplying knowledge about which streams, species, elevations, and directions will yield the most robust models in the spatially diverse terrain of the PNW. Chapter 4 is a collaborative synthesis of climate change research in the Columbia River Basin (CRB). Results show that spatial distribution and thematic content of research varies across an international border, with greater concentrations of research in the United States than Canada. A general scarcity of social science research and limited interaction between social and biophysical content reinforces the need for increased collaboration between disparate disciplines. Future research focus areas should include research related to climate change adaptation and mitigation, increased integration between social and biophysical sciences, and collaborations that bridge the international border for a more unified basin-wide focus. Focusing on these new directions for research will increase the potential for science and management communities to co-produce actionable science and effective responses to climate change. With the utilization of dendrochronological techniques, many of the interacting drivers of species-specific tree growth in the PNW were discovered. Shade tolerance, disturbance dynamics, and hydroclimate all influence conifer growth in the region. The relationships between streamflow and growth are heightened for trees growing in extreme climates, and these relationships are driven by geographical features. Overall, this dissertation provides insight into dendrochronological techniques as well as silvicultural management in moist mixed conifer forests; it also lends support that forest management can assist tree growth and alter growth-drought relationships depending on species. Finally, the dissertation offers additional evidence to the decades-long theory that trees growing at the edges of their ranges show higher sensitivity to limiting factors.doctoral, Ph.D., Water Resources -- University of Idaho - College of Graduate Studies, 2020-0
Causes and consequences of Chinese privet (Ligustrum sinense lour.) invasion in hydrologically altered forested wetlands
No full textWhat drives invasive species success? My research consists of four studies aiming to answer this question for Ligustrum sinense. The four projects are: (1) Synthesis of invasion literature within passenger-driver-backseat driver frameworks; (2) hydrochory investigation of water as a dispersal mechanism for invasion; (3) ecohydrology investigation of inundation effects on seed viability of L. sinense; (4) dendrochronology study of the effects of stream channelization and L. sinense invasion on bottomland oak tree growth. Results suggest that L. sinense initially invaded habitats that were hydrologically altered, resulting in drier conditions and a "novel niche." Dispersal via hydrochory allowed L. sinense to quickly colonize the novel niches. Once established, L. sinense competed with native oak species contributing to reduced growth rates, an "invasion meltdown." Control strategies should aim to remove L. sinense and return natural hydrologic regimes, or should consist of human-assisted re-establishment of native species that can thrive in altered conditions
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
