1,721,146 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
Diverse but uncertain responses of picophytoplankton lineages to future climate change
No full textClimate change is projected to modify the physical and chemical environment of the ocean, but the quantitative impact on the distribution of phytoplankton groups is unclear. Most Earth System Models (ESMs) predict future declines of phytoplankton in low latitude waters, contradicting observations showing that picophytoplankton can reach high abundance in warm waters. Here, we used a historic and three climate scenarios along with quantitative niche models to project Prochlorococcus, Synechococcus, and picoeukaryotic phytoplankton distributions for the year 2100. First, we found global responses with up to 50% and 9% increase for Prochlorococcus and Synechococcus abundances, respectively, and 8% decrease for picoeukaryotic phytoplankton. All groups increased in abundance at low latitude, and Synechococcus and picoeukaryotic phytoplankton showed bands of decreases and increases in mid- and high-latitudes, respectively. Prochlorococcus temporal trends were consistent among ESMs and increased with the strength of the scenario, while Synechococcus and picoeukaryotic phytoplankton showed mixed results. Second, we evaluated sources of uncertainty associated to future projections. The anthropogenic uncertainty, associated to climate scenarios, increased with time and was relevant for Prochlorococcus. The environmental and biological uncertainty, associated to ESMs and niche models, respectively, represented the largest fraction but differed among lineages. Quantifying uncertainties is key because the predicted differences in the future distribution and abundance can have large-scale consequences on ocean ecosystem functioning.Fil: Flombaum, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Martiny, Adam C.. University of California at Irvine; Estados Unido
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
Recommended from our members
A Novel Assessment of Antibiotic Resistance
Full text linkIt is important to understand the evolution and prevalence of antibiotic resistance as it is considered a major threat to global public health. Predicting where new antibiotic resistance (AR) genes will rise is a challenge and especially important when new antibiotics are developed. Adaptive resistance allows sensitive bacterial cells to become transiently resistant to antibiotics through changes in gene expression. This provides an opportune time for cells to develop more efficient resistance mechanisms and permanent resistance to higher antibiotic concentrations. Intraspecific genomic diversity may be a driving force in the emergence of adaptive antibiotic resistance. Here, I use an amplification assay adapted from functional metagenomics to investigate cryptic antibiotic resistance, an adaptive resistance mechanism, across eight micro-diverse Escherichia coli from clinical and laboratory origins. Cryptic (unclassified) AR genes primarily conferred resistance within clinical strains as opposed to known AR genes as hypothesized. Most genes conferring resistance within multiple strains were classified AR genes. Cryptic AR genes are highly variable as most conferred resistance in only one strain. Hydrophilic antibiotics are more likely to induce cryptic resistance as resistance occurred to all hydrophilic antibiotics tested. These studies may help detect novel AR genes that confer resistance when upregulated. Additionally, it is important to study antibiotic resistance in the environment, including coastal water. At the beach, people may ingest bacteria harboring AR genes which can lead to infection and/or transfer of genes to commensal and opportunistic pathogens resident in the human microbiome. The ingestion of seafood potentially harboring antibiotic resistant bacteria can lead to indirect contact with antibiotic resistance. Through a ten-year time series, I used metagenomics to provide a comprehensive understanding of the AR genes present within Newport Beach, CA seawater, the temporal distribution of these genes, and the factors driving their frequencies. I found that seasonal and interannual trends of AR genes vary by gene and the taxa carrying them as opposed to a general increase of most resistance genes during specific seasons. However, I found that precipitation and Enterococcus levels may be accurate indicators for total AR gene levels in Newport beach coastal water. Mostly marine taxa carry AR genes in Newport Beach coastal water, but there are also terrestrial taxa and opportunistic pathogens harboring AR genes. Non-marine taxa may be washed in with rain, people, or sewage spills. By using metagenomics, I was able to elucidate the AR gene reservoir in Newport Beach coastal water
Recommended from our members
Linking Microbial Communities with Geochemical and Physical Dynamics across Marine Environments
No full textMarine bacterial metabolism of oxygen (O), carbon (C), nitrogen (N), phosphorus (P), iron (Fe), and silica (Si) are essential for elemental cycling on our planet. Because of this, understanding the spatial distribution of marine bacteria, how these bacteria are functioning and interacting with physical processes, and what environmental conditions impact them is essential for understanding current biogeochemical dynamics and for predicting how these dynamics might change in the future. My dissertation research is divided into three projects that aimed to connect large microbial genomic datasets with geochemical and physical processes in open ocean and coastal ecosystems. These studies consisted of a biogeographic survey of the Indian Ocean, an in-depth analysis of mesoscale eddies, and a coastal study at Newport Beach, California.In the first chapter, I linked broad-scale spatial patterns of marine bacteria with geochemical and physical dynamics across the eastern and western Indian Ocean. To achieve this, I incorporated 16S rRNA gene sequences from 465 samples with in-situ CTD data, nutrient concentrations, particulate organic matter (POM) concentrations, stoichiometric ratios, and remote sensing data of sea surface height and geostrophic currents. This extensive analysis revealed 23 unique community structures within the Indian Ocean. It highlighted the southeastern gyre as the area with the largest gradient in bacterial alpha-diversity, identified that the Indian Ocean microbiome was dominated by a core set of taxa, and linked changes in community structure with transitions in physical and geochemical conditions. Importantly, the study identified distinct community structures within mesoscale studies, which served as the foundation for my next chapter.
In the second chapter, I investigated the role of mesoscale eddies in shaping bacterial community composition and function across various Indian Ocean regions. This project integrated genomics (16S rRNA and short-read metagenomes), nutrient concentrations, and remote sensing data of 26 eddies of varying age, intensity, and size. Within this study, mesoscale eddies were viewed as physical disturbances that altered communities through dispersal and/or environmental selection. It was found that the origin of the eddy (i.e., coastal waters versus open ocean waters) played a pivotal role in determining how dispersal and environmental selection affected microbial community outcomes.
In the third chapter, I examined the interactions between pollutants, marine bacterial diversity and function, and ecosystem recovery within the coastal waters of Newport Beach, California, following the Orange County oil spill. This investigation incorporated short-read metagenomic data, flow cytometry data, polycyclic aromatic hydrocarbon (PAH) concentrations, nutrient concentrations, and POM concentrations. The acute bacterial response to the oil spill was assessed by comparing metagenomically derived taxonomic and functional trends to a 10-year time-series. Notably, there was a rapid and anomalous decline in the abundance of the dominant picophytoplankton, Synechococcus. This decline was coupled with an increase in sulfur-oxidizing and potential hydrocarbon-degrading heterotrophic lineages. There was a lagged response in taxonomy and function to peaks in total PAHs. One week after peaks in total PAH concentrations, the largest shifts in taxonomy were observed, and one week after the taxonomy shifts were observed, unique functional changes were seen. This pattern of response was observed two times during our sampling period and corresponded with the potential resuspension of PAHs. Thus, the impact of the oil spill was temporally extended and demonstrates the need for continued monitoring long after initial exposure
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
- …
