1,721,162 research outputs found
Chlorophyll Bloom Dynamics and Associations with Mesoscale and Submesoscale Features in the North Pacific Subtropical Gyre
Get PDFLarge summer chlorophyll blooms spanning hundreds of square kilometers and persisting for weeks-months, are consistently observed in satellite records of the Northeast Pacific Subtropical Gyre (NPSG), at an approximate latitude of ~30°N. These blooms occur at a near annual rate, and uniquely within the late summer months of June-October. Understanding the potential impacts and biophysical drivers of these chlorophyll anomalies is both ecologically and climatologically important. These large-scale blooms can export carbon from the upper ocean to the deep ocean and fuel the productive fisheries found in the ecologically important transition zone between the North Pacific Subtropical Gyre and the subpolar gyre. The purpose of this project is to characterize chlorophyll blooms in the NE Pacific Gyre, as well as describe their association with submesoscale and mesoscale features to identify potential physical drivers. First, an analysis of the merged satellite CHL product is done to characterize the magnitude, frequency, and geographic location of chlorophyll blooms in the NPSG. Then the sea level anomaly (SLA) and finite sized Lyapunov exponents (FSLE) were used to identify sub-mesoscale and mesoscale features i.e. fronts, anti-cyclonic eddies, and cyclonic eddies. Through this process, we provide a quantitative characterization of chlorophyll anomalies in the NPSG. Further analyses present a case-study time-series of the 2018 bloom in order to better understand the time resolved change in phytoplankton biomass and how it relates to physical drivers of biomass growth and accumulation. To achieve this, a generalized additive model (GAM) is used to determine the effects of SLA and SSTA on the CHL anomaly signal of the 2018 plankton bloom.M.S
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
Applications of the Underwater Vision Profiler for Particle Annotation in the Oligotrophic North Pacific Subtropical Gyre
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DEVELOPING AND ASSESSING A DIVERSE PLANKTON IMAGERY TRAINING SET FOR MACHINE-LEARNING PLANKTON CLASSIFICATION IN THE NORTH PACIFIC SUBTROPICAL REGION
Get PDFABSTRACT
The Imaging FlowCytobot (IFCB) has a continually growing role in oceanographic research, particularly in the exploration of microbial life within the North Pacific Subtropical Gyre (NPSG).
However, the vast amount of data generated by the IFCB poses a challenge for manual sorting and taxonomic classification. This study addresses this challenge by developing a Convolutional Neural Network (CNN) training set to efficiently categorize IFCB images into taxonomic groups. Specifically focusing on the diatom Hemiaulus and ciliate phylum Ciliphora during a research cruise within the NPSG in the summer of 2021, the study aims to quantify the CNN's performance compared to manual annotations of IFCB images taken on this cruise, providing insights into the CNN’s accuracy and precision over time. Statistical analyses of the CNN’s machine learning-based classifications indicate a high accuracy in the automated identification of Hemiaulus and Ciliophora. Analysis of biovolume and particle number concentration reveals trends in taxonomic abundance over the course of the cruise. Despite morphological changes of Hemiaulus as it loses structure over time, the CNN demonstrates an overall improvement in accuracy as the cruise progresses, particularly for Hemiaulus. This study highlights the development of a robust training set of roughly 76,000 images, allowing the CNN to accurately classify images collected within the NPSG.ABSTRACT
The Imaging FlowCytobot (IFCB) has a continually growing role in oceanographic research, particularly in the exploration of microbial life within the North Pacific Subtropical Gyre (NPSG).
However, the vast amount of data generated by the IFCB poses a challenge for manual sorting and taxonomic classification. This study addresses this challenge by developing a Convolutional Neural Network (CNN) training set to efficiently categorize IFCB images into taxonomic groups. Specifically focusing on the diatom Hemiaulus and ciliate phylum Ciliphora during a research cruise within the NPSG in the summer of 2021, the study aims to quantify the CNN's performance compared to manual annotations of IFCB images taken on this cruise, providing insights into the CNN’s accuracy and precision over time. Statistical analyses of the CNN’s machine learning-based classifications indicate a high accuracy in the automated identification of Hemiaulus and Ciliophora. Analysis of biovolume and particle number concentration reveals trends in taxonomic abundance over the course of the cruise. Despite morphological changes of Hemiaulus as it loses structure over time, the CNN demonstrates an overall improvement in accuracy as the cruise progresses, particularly for Hemiaulus. This study highlights the development of a robust training set of roughly 76,000 images, allowing the CNN to accurately classify images collected within the NPSG.
Keywords: Taxonomic sorting, machine learning, zooplankton, Imaging FlowCytoBot
(IFCB), North Pacific Subtropical Gyre (NPSG), ocean microbiology
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
DEVELOPING AND ASSESSING A DIVERSE PLANKTON IMAGERY TRAINING SET FOR MACHINE-LEARNING PLANKTON CLASSIFICATION IN THE NORTH PACIFIC SUBTROPICAL REGION
No full textDispelling 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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