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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
RELATING FLUVIAL GEOMORPHOLOGY TO MACROINVERTEBRATE DISTRIBUTION
Get PDFModern rivers undergo constant stress from disturbances such as bank stabilization, channelization, dams, and water expenditures. As these anthropogenic activities persist, efficient methods of characterizing rivers remain essential. Macroinvertebrates are an important feature in evaluating fluvial health, because they are often the first to react to contaminants. These toxins can be transferred through macroinvertebrates to other trophic levels. The purpose of this research was to use a geospatial model to differentiate instream macroinvertebrate habitats, and determine if the model is a viable method for stream evaluation. Through the use of ArcGIS and digital elevation models, the geomorphology of the Qu’Appelle River, Saskatchewan was assessed.
Four geomorphological characteristics of the river were isolated (sinuosity, slope, fractal dimension, stream width) and clustered through a Principle Component Analysis, yielding sets of river reaches with similar geomorphological characteristics, called typologies. These typologies were mapped to form a geospatial model of the river, and grouped into geomorphological response units (GRUs). Macroinvertebrate data were aligned to the model, revealing relationships between macroinvertebrate taxa and fluvial geomorphology. A Kruskal-Wallis analysis and post hoc pairwise multiple comparisons pinpointed significant relationships between several genera and typologies. Furthermore, certain GRUs contained more sensitive macroinvertebrate families and healthier levels of diversity than other GRUs. Typologies were better suited to relate geomorphology to macroinvertebrate taxa, because they represented a more direct relationship to localised geomorphological characteristics than GRUs
Screening and Examining “Exotic” Chemicals in Swift Current Creek, SK, Canada
Get PDFA wastewater treatment plant (WWTP) is situated on Swift Current Creek, SK. Although the plant carries out complete secondary treatment followed by UV disinfection, a suite of chemicals is still released into the receiving water. In addition, the City of Swift Current used lagoon treatment for 27 years prior to the construction of the WWTP and thus chemicals in the lagoon could also pose a potential threat to nearby ecosystems. Swift Current Creek flows into Lake Diefenbaker on the South Saskatchewan River system, which is a major drinking water source for Saskatchewan residents. Therefore, the aim of this study was to construct a contaminant chemical profile of the WWTP wastewater and the receiving water throughout the year to monitor the release and fate of pollutants.
Chemical contaminants of interest included hormones, insecticides/pesticides, industrial chemicals and pharmaceuticals and personal care products. A total of 9 sites upstream, downstream and on-site of the WWTP, including the lagoon, were sampled once or twice a month in 2011 and 2012. Organic compounds were extracted via solid-phase extraction using HLB cartridges for effect-directed analysis. Recombinant H4IIE-luc, MVLN and MDA cell lines were used to detect dioxin- or PAH-like, estrogenic and androgenic activities, respectively. An HPLC Quadrupole-Orbitrap Mass Spectrometer was used to detect and semi-quantify target chemicals by either full scan or by selected ion monitoring. A mixture of twenty-two chemicals representing each group of compounds was used as a standard for the analysis.
No dioxin- or PAH-like activities were detected using the H4IIE-luc bioassay. Significant androgenic activities were detected in influents as expected. However, post-treatment effluent samples illustrated near 100% removal of androgenicity. No estrogenic activities could be detected in any samples, probably due to background levels of hormones found in the growth media that compromised the sensitivity of MVLN assay. Therefore, Orbitrap Hi-Res coupled to HPLC was used for instrumental analysis to semi-quantify natural and synthetic estrogen mimics. Estrogen equivalency (EEQ) was calculated from instrument analysis results. Seasonal variations were observed as March samples had the highest concentrations of EEQ. The March effluent sample had an EEQ of 2.26 ng/L compared to <0.5 ng/L from the other three sample periods. Longitudinal variations were also apparent, suggesting that input sources other than the WWTP may be present.
Four selected sampling dates representing different seasons of the year (August for late summer, September for early fall, January for middle of winter, and March for early spring) were also analyzed using the Orbitrap. Pesticides were found at greater concentrations in surface water than in raw and treated wastewater. Evidence suggested a major source of input of pesticides to be agricultural leaching and runoff rather than municipal wastewater. Hormones were efficiently removed through the wastewater treatment process as only low levels were detected (mean < 1 ng/L for effluents and downstream surface water). PPCPs exhibited more variable characteristics, as some chemicals had near 100% removal (caffeine and DEET) while others were rather persistent (carbamazepine). Residual concentrations found in effluents and downstream surface waters were in a much wider spectrum, with maximum concentrations of up to hundreds of ng/L. Seasonal variations were observed among PPCPs as well. Concentrations of triclosan and trimethoprim were especially higher in March. Seasons that exhibited elevated chemical concentrations coincided with the spawning seasons of aquatic organisms and thus environmental impacts should be further assessed
An investigation into the past and present ecological status of Lake Diefenbaker using paleolimnological and whole sediment toxicity techniques
Get PDFRecent anecdotal evidence has suggested that Lake Diefenbaker, a large reservoir in southern Saskatchewan, Canada, has been experiencing an increased frequency and severity of algal blooms, suggesting significant alterations in water quality. Due to limited historical water quality monitoring, a paleolimnological investigation of Lake Diefenbaker sediments was conducted in order to interpret spatial and temporal trends in the physicochemistry of sediment cores collected from mid-channel locations along a spatial gradient. Total phosphorus and three sediment species of phosphorus (apatite inorganic phosphorus, non-apatite inorganic phosphorus (NAIP) and organic phosphorus (OP) were measured along the vertical profile of the cores to interpret nutrient loading trends. Trends in historical primary productivity were inferred based on total organic carbon, total nitrogen, δ15N values and the organic carbon to nitrogen (C:N) ratios. In addition, sub-fossil biological remains of diatoms and chironomid larvae were isolated from selected subsections of the sediment cores and identified to assess shifts in community compositions and to infer historical changes in reservoir water quality conditions.
Up-reservoir sampling locations showed consistent concentrations of total phosphorus and the three species of phosphorus, organic carbon, nitrogen, δ15N values and C:N ratios in the vertical profile of collected sediment cores. This suggested relatively consistent nutrient loading and primary production in the up-reservoir regions for the period represented by the core profiles. Down-reservoir sediment cores showed an increasing trend in total phosphorus concentration, mainly in the more biologically available NAIP and OP fractions, and enrichment in organic carbon, nitrogen and 15N in more recently deposited sediments. This combined with a decreasing C:N ratio in more recent sediments suggests increased nutrient loading to the sediments and increasing primary productivity at down-reservoir sites. Strong correlations between sediment total organic carbon content and the more biologically available sediment phosphorus fractions (NAIP and OP) suggest that phosphorus deposition patterns are strongly influenced by primary productivity within the reservoir.
The compositions of diatom and chironomid communities were consistent over time at up-reservoir locations, with Stephanodiscus parvus dominating the diatom communities and Procladius sp. dominating the chironomid communities. This suggests relatively stable and consistent trophic status and primary productivity in this region. Conversely, major shifts occurred in the diatom and benthic chironomid communities at down-reservoir locations. These shifts were consistent with typical reservoir ontogeny. A shift in dominance from Stephanodiscus parvus to Asterionella formosa, Tabellaria flocculosa and Stephanodiscus medius followed by a shift to Aulacosiera ambigua suggests an initial period of eutrophy, followed by a period of mesotrophy, and finally a transition into a more productive system in recent years. The increase in relative abundance of the chironomid tribe Tanytarsini suggests rising levels of organic matter sedimentation, likely due to increased autochthonous primary productivity. Low chironomid head capsule counts were observed at all locations within Lake Diefenbaker. Despite the low head capsule counts, a 10-day whole-sediment toxicity test using Chironomus dilutus, revealed that Lake Diefenbaker sediments, in proximity to two potential point sources of contamination (aquaculture and municipal discharge), as well as two reference locations, were not of toxicological concern. Despite the lack of toxicity associated with Lake Diefenbaker sediments, it was concluded that Lake Diefenbaker sediments are likely poor habitat for chironomids.
This study suggests that primary productivity and nutrient status has remained relatively constant at up-reservoir locations for the period represented by the collected cores. This is likely due to up-reservoir locations being more riverine than down-reservoir regions, which results in increased turbidity causing phytoplankton populations to be light limited. Primary productivity appears to increase spatially with increased distance down reservoir, likely due to a gradual transition to more lacustrine environments, resulting in less turbidity and less light limitation. Temporally, down-reservoir locations appear to be showing increases in primary productivity and nutrient entrainment in sediments. This is likely a result of increased nutrient availability over time and entrainment of these nutrients in sediments at down-reservoir locations by primary producers
Toxicity of surface water and pore water from an oil sands pit lake (Lake Miwasin) to Daphnia
No full textCanada holds approximately one-third of the world's confirmed crude oil reserves, primarily concentrated in the Alberta Oil Sands (AOS) region, in the form of bitumen. However, the extraction process of oil sands generates significant volumes of tailings and process water, which raises concerns about their potential effects on aquatic life and the need for remediation. Lake Miwasin, constructed in 2018, serves as a pilot-scale pit lake and a model for this context. It features treated fluid tailings overlaid by a mixture of oil sands process-affected water (OSPW) and freshwater, exhibiting seasonal stratification. Since its establishment, Lake Miwasin has been colonized by various organisms, including the Crustacean, Daphnia pulex. Monitoring data from Lake Miwasin has shown the presence of compounds in both water and sediment that could be detrimental to aquatic organisms. Therefore, the primary goals of this research were to assess surface water and pore water toxicity, including an evaluation of selenium (Se) bioaccumulation in Daphnia species exposed to the conditions representative of Lake Miwasin at its early development stages and possibly other future pit lakes in the AOS region.
This study examined the toxicity of Lake Miwasin surface water (LMW) and pore water (LMP) using lab-cultured and native Daphnia species. Interestingly, LMW exhibited no acute or chronic toxicity towards D. magna and D. pulex (lab strains) and the native Daphnia sp. (collected from Humboldt Lake, SK, Canada). However, LMP demonstrated acute toxicity to both lab strains and the native D. pulex (collected from Lake Miwasin, AB, Canada). Lake Miwasin pore water also negatively impacted lab D. pulex reproduction, leading to a reduced number of offspring. Salinity emerged as a significant stressor in LMP, and a Toxicity Identification Evaluation (TIE) phase I suggested ammonia and metals in LMP as potential contributors to the observed toxicity in the tested organisms. On a related point, results showed that concentrations of dissolved Se in LMW from 2019 to 2021 exceeded the Canadian Council of Ministers of Environment (CCME) water quality guidelines for long-term aquatic life protection (1 µg/L), and the British Columbia Ministry of Environment (BC MoE) water guideline alert concentration for the protection of aquatic life (1 µg/L). The latter water guideline was also adopted by the Government of Alberta. Further, another experiment assessed Se bioaccumulation in D. pulex through dissolved and dietary exposure routes, drawing comparisons to native specimens collected from Lake Miwasin. In semi-static tests (12 days), lab strain D. pulex exposed to selenate [Se(VI)] showed a Se concentration-dependent increase from days 5 to 12 for most treatments, whereas a lower bioaccumulation occurred at higher Se concentrations, which suggests a potentially internal regulatory mechanism. Native D. pulex exposed to LMW in laboratory conditions showed that Se bioaccumulation levels were similar to those of D. pulex collected directly from Lake Miwasin. Despite these findings, the Se concentrations in D. pulex from both lab exposures and Lake Miwasin collections remained below available regulatory guidelines for invertebrate tissue (4 µg/g), suggesting that D. pulex appears to pose minimal risk as a food source in the Lake Miwasin ecosystem.
These findings provide useful insights into the toxicity of Lake Miwasin water to aquatic invertebrates, the potential for Se bioaccumulation in daphnids in Lake Miwasin, the potential enhancement of pit lake monitoring programs, and the decision-making regarding the use of end pit lakes in the reclamation of OSPW and oil sands tailings
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
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