1,720,959 research outputs found
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
Invasive species detection from RGB aerial imagery: investigating links between plant characteristics and transfer learning success
Full text linkM.S
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
High resolution habitat suitability modeling for a narrow-range endemic alpine Hawaiian species
Full text linkMapping potentially suitable habitat is critical for effective species conservation and management but can be challenging in remote areas exhibiting complex substrate heterogeneity. An approach that combines a diverse set of nonintrusive spatial data collection techniques with field validation can lead to a better understanding of landscapes and species distributions. Nysius wekiuicola, commonly known as the wēkiu bug, is the most studied arthropod species endemic to the Maunakea summit in Hawai‘i, yet details of its life history and geographic distribution remain poorly understood. The wēkiu bug, a species of concern, provides an excellent opportunity to employ nonintrusive spatial data collection techniques to answer previously elusive questions about habitat quality and composition. To predict the geographic distribution of N. wekiuicola, MaxEnt habitat suitability models were generated from fifteen years of species occurrence data and a variety of spatial datasets, including high resolution digital elevation models, surface mineralogy based on hyperspectral remote sensing, and climate variables. MaxEnt model results indicate that the variables with the highest influence (in terms of percent contribution) were elevation (78.2%), presence of nanocrystalline hematite surface minerals (13.7%), and minor contributions from aspect, slope, and other surface minerals. A limitation of this study is that many historic trapping sites were placed near roads and other accessible pre-determined locations instead of being systematically or randomly placed, meaning final model results may be biased and not entirely indicative of true wēkiu bug distribution. Although climate data is available, these climatic variables were auto-correlated and at too coarse of a spatial resolution to include in the final analysis. A trapping experiment based on surface mineralogy and geomorphic position affirmed that both elevation and surface mineralogy play significant roles in the spatial patterns of wēkiu bugs, but observed presence upslope on a cinder cone and absence downslope, even within the same predominant surface mineral, suggests that other habitat variables may be at play such as competition/predation. The models of wēkiu bug range and predicted suitable locations will be incorporated into management efforts and restoration goals for land managers of Maunakea. In addition, environmental data layers created in this initiative have now unlocked the ability to create suitability models for other species of interest on Maunakea.M.S.University of Hawaii at Hil
QUANTIFYING SHORELINE CHANGE AT THREE DIVERSE COASTAL GEOMORPHOLOGIES ON HAWAI‘I ISLAND
Full text linkHawai‘i Island’s coastal communities are in a weak position for adapting to the impacts of sea-level rise (SLR), coastal erosion, and subsidence. Though bounded by nearly 430 km of ecologically, culturally, and economically important coastline, Hawai‘i Island has never had a comprehensive assessment, or systematic monitoring, of long-term and short-term shoreline change rates to inform local coastal zone management policies. Consequently, occurrences of unsustainable coastal development have resulted in significant impacts to property and nearshore resources. To better understand and manage coastal vulnerabilities, we quantified shoreline change from the mid-twentieth century to the present for three diverse geomorphic coastal settings on Hawai‘i Island. These sites are a calcareous beach (Hāpuna State Beach Park), a sea cliff (Honoli‘i Beach Park), and a subsiding coastal lava field (Kapoho/Hawaiian Vacation Land). In order to quantify change, we produced shoreline position data using historic aerial photographs and three-dimensional datasets derived from monthly small unmanned aerial system (sUAS) surveys collected over a 12 month period. These data were merged with SLR and subsidence projections using GIS to estimate and visualize current and future shoreline locations at our three sites. From our monthly survey data at Hāpuna Beach, we found the shoreline to be highly dynamic, exhibiting a mean intra-annual shoreline positional variation of 7.33 ± 2.29 m. We also found that Hāpuna Beach experiences long-term erosion (1969-2018) at a rate of -0.18 ± 0.17 m yr-1. Along the Honoli‘i sea cliff, we quantified long-term erosion of -0.13 ± 0.26 m yr-1, with a maximum retreat of 9.5 m between 1964 and 2018. Our analyses for Kapoho found that present-day extreme flooding events (i.e. king tides) already cause tidal inundation 60 m inland from the current mean higher high water mark. If SLR and subsidence rates persist as expected, the entire Kapoho study site will experience flooding within 25 years. Through this study we were able to quantify, for the first time, shoreline changes exhibited across Hawai‘i Island’s diverse and dynamic coast. We also demonstrated the viability of sUAS as an effective tool for high resolution coastal monitoring. Our results provide insights to the chronic, seasonal, and episodic coastal processes that impact coastal communities and resources on Hawai‘i Island, and can help Hawai‘i County planners develop necessary adaptations to coastal management strategies.M.S.University of Hawaii at Hil
Mapping Biological Soil Crust Cover in the Kawaihae Watershed
Full text linkHistorical land use patterns on Hawai’i Island have created degraded dryland ecosystems that are at high risk for erosion. In places such as the Kawaihae watershed in leeward Kohala, the impacts of sediment deposition from the watershed have detrimentally affected coastal marine ecosystems by decreasing habitat quality and burying important cultural sites. Due to the extensive and long-term effects of erosion, it is important to understand and protect non-traditional agents that may help to hold sediments in place. Biological soil crusts are communities of photosynthetic microorganisms that grow over mineral soil in arid and semi-arid ecosystems and are known to increase soil stability. Despite their potential to mitigate erosion, the distribution of biocrusts in degraded drylands on Hawai’i Island is unknown. We mapped biocrusts in the Kawaihae watershed, a semi-arid landscape prone to erosion, using imagery collected by small unmanned aerial systems (sUAS) at three spatial resolutions (1.15, 2.05 and 2.80 cm/pixel). Using a pixel-based methodology, we produced classifications with overall accuracies ≥85% at all three resolutions. As biocrust development is associated with increasing soil stability, we also explored this relationship in the Kawaihae watershed. We identified 3 different biocrust levels of development (LOD) and conducted soil aggregate stability testing at all development levels. We found that there was a significant increase in soil stability between soils without surface biocrusts (LOD score of 0) and those with biocrusts at any development level (LOD 1-3). More highly-developed biocrusts imparted greater soil stability than less-developed biocrusts, but the impact on soil stability reached a ceiling beyond biocrust LOD 1. In addition, we applied our mapping methodology to investigate the direct impacts of biocrusts on soil loss. We overlaid our classified maps with digital surface models (DSMs) from data sets covering a 2.75-year time span. We found trends of varying soil loss between biocrust and bare soil areas, but more field work is needed to verify our results. We also explored the effects of grazing animals on biocrust cover by comparing classified images of a grazed site and a grazing-exclusion site. We found differences in biocrust coverage between the sites, including differing proportions of the land cover types present, but additional field data collection is necessary prior to drawing definitive conclusions. Overall, our project provides a new biocrust mapping methodology that could be used by researchers and land managers globally and adds insight into the role of biocrusts in erosion prevention in the Kawaihae watershed and similar arid/semi-arid landscapes.M.S.University of Hawaii at Hil
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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