1,720,985 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
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
Molecular mechanisms involved in prokaryotic cycling of labile dissolved organic matter in the sea
No full textRoughly half of the global primary production originates from microscopic phytoplankton in marine ecosystems, converting carbon dioxide into organic matter. This organic matter pool consists of a myriad of compounds that fuel heterotrophic bacterioplankton. However, knowledge of the molecular mechanisms – particularly the metabolic pathways involved in the degradation and utilization of dissolved organic matter (DOM) – and transcriptional dynamics over spatiotemporal gradients are still scarce. Therefore, we studied the molecular mechanisms of bacterioplankton communities, including archaea, involved in the cycling of DOM, over different spatiotemporal scales in experiments and through field observations. In seawater experiments, we found a divergence of bacterioplankton transcriptional responses to different organic matter compound classes (carbohydrates, nucleic acids, and proteins) and condensation states (monomers or polymers). These responses were associated with distinct bacterial taxa, suggesting pronounced functional partitioning of these compounds in the Sea. Baltic Proper mesocosms amended with two different river loadings (forest versus agriculture river water) revealed a divergence in gene expression patterns between treatments during bloom decay. This was particularly true for genes in phosphorus and nitrogen metabolism, highlighting the importance and sensitivity of interaction effects between river- and phytoplankton-derived DOM in regulating bacterial activity responses to changes in precipitation-induced riverine runoff. In shipboard mesocosms in an Atlantic coastal upwelling system, we found significant changes in bacterioplankton transcription of hydrolyzing enzymes and membrane transporters from phytoplankton bloom development to senescence, primarily driven by phytoplankton-derived DOM and dissolved organic carbon dynamics. These responses differed substantially between bacterial orders, suggesting that functional resource partitioning is dynamically structured by temporal changes in DOM quantity and quality. Further analysis of these gene systems in a stratified fjord revealed pronounced divergence in transcription with depth and between bacterial taxa; moreover, transcription was more variable in the surface waters. This highlights the interplay between functional and physical partitioning of biogeochemical cycles. Collectively, the findings in this thesis contribute novel insights into the interdependency between prokaryotes and DOM by shedding light on the mechanisms involved in DOM cycling over ecologically relevant spatiotemporal scales
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
Usage of metabolic inhibitors to quantify bacterial and archaeal activity in meso- and bathypelagic waters of the North Atlantic
No full textDie Verwendung von Inhibitoren, die spezifisch den Metabolismus von Bakterien und Archaeen inhibieren, ist hilfreich um gruppenspezifische Aktivitäten zu messen. Im Zuge dieser Arbeit testeten wir die Inhibierungsspezifität von Erythromycin (EMY) und N1-guanyl-1,7-diaminoheptan (GC7) an Prokaryoten des offenen Ozeans, die bis dato noch nicht in diesem Umfang durchgeführt worden ist. Wir stellten die Hypothese auf, dass EMY behandelte Proben die Produktivität der Archaeen repräsentieren, wohingegen GC7 behandelte Proben als guter Proxy der bakteriellen Aktivität angesehen werden können. Wasserproben wurden im Juni und Juli 2012 aus verschiedenen Tiefen im Nordatlantik genommen. Die Inhibierung der 3H-Leucin Aufnahme wurde mit Hilfe von Catalyzed Reporter Deposition Fluorescence In Situ Hybridisierung in Kombination mit Mikroautoradiographie (MICRO-CARD-FISH) und Flüssigszintillationszähler gemessen. Des Weiteren wurden Durchflusszytometrie, CARD-FISH und MICRO-CARD-FISH angewendet, um die mikrobielle Abundanz und die Zusammensetzung der mikrobiellen Gemeinschaft zu bestimmen. Die mikrobielle Abundanz nahm mit der Tiefe exponentiell ab, von 3.3 x 105 zu 8.1 x 104 Zellen mL-1. Die Leucin-Aufnahme korrelierte gut mit der mikrobiellen Abundanz und schwankte zwischen 51.6 und 1.9 nmol Leucin m-3 d-1. Gemessen an DAPI-Zählungen, schwankte der Anteil an Bakterien zwischen 28.6 und 46.5%, während SAR11 zwischen 12.2 und 20.8% ausmachte. Gemessen an gesamten DAPI-Signalen machten Thaumarchaeen zwischen 10.5 und 23.2% und Euryarchaeen zwischen 2.3 und 11.5% aus. Entgegen bisheriger Annahmen, führte EMY zu einer vergleichbaren Inhibierung der Leucin-Aufnahme von Bakterien und Archaeen (~61%). GC7 reduzierte die Substrataufnahme, ähnlich wie EMY, allerdings war die 3H-Leucin-Aufnahme der Bakterien zu 39% und die der Archaeen zu 54% reduziert. Wir schlussfolgern daher, dass der getestete Doppelte-Inhibierungsansatz scheinbar zu unspezifisch ist, um damit die Aktivität von Bakterien und Archaeen im offenen Ozean unterscheiden zu können.Domain-specific metabolic inhibitors are useful to quantify the distribution of prokaryotic activity among Bacteria and Archaea in the oceanic water column. Although applied to marine prokaryotic communities in several studies, an in-depth analyses of the specificity of erythromycin (EMY) and N1-guanyl-1,7-diaminoheptane (GC7) to inhibit bacterial and archaeal activity, respectively, has not been done yet. We tested this domain specificity of these two inhibitors on natural prokaryotic assemblages from the North Atlantic. We hypothesized that in EMY-treated samples archaeal activity is obtained, whereas in GC7-treated samples bacterial activity will be measured. Heterotrophic prokaryotic activity was estimated via 3H-leucine incorporation on the bulk and on the single-cell level using catalyzed reporter deposition fluorescence in situ hybridization combined with microautoradiography (MICRO-CARD-FISH). In the water masses used for this inhibitor test, the contribution of Bacteria to total DAPI counts ranged from 29 to 47%, while SAR11 comprised 12 to 21% of the DAPI counts, suggesting that SAR11 contributed substantially to bacterial community. The contribution of Thaumarchaeota ranged from 11 to 23% and Euryarchaeota from 2 to 12% of DAPI counts. In EMY-treated samples leucine incorporation was reduced by ~61%. Using single-cell analyses to test the specificity of the inhibitors, GC7 reduced the substrate uptake of Bacteria and Archaea by 39% and 54%, respectively. Hence, we conclude that neither EMY nor GC7 is entirely domain-specific when applied to complex marine prokaryotic communities. Our results, therefore, call for caution when using these inhibitors to assess domain-specific activities
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
Molecular mechanisms involved in prokaryotic cycling of labile dissolved organic matter in the sea
No full textRoughly half of the global primary production originates from microscopic phytoplankton in marine ecosystems, converting carbon dioxide into organic matter. This organic matter pool consists of a myriad of compounds that fuel heterotrophic bacterioplankton. However, knowledge of the molecular mechanisms – particularly the metabolic pathways involved in the degradation and utilization of dissolved organic matter (DOM) – and transcriptional dynamics over spatiotemporal gradients are still scarce. Therefore, we studied the molecular mechanisms of bacterioplankton communities, including archaea, involved in the cycling of DOM, over different spatiotemporal scales in experiments and through field observations. In seawater experiments, we found a divergence of bacterioplankton transcriptional responses to different organic matter compound classes (carbohydrates, nucleic acids, and proteins) and condensation states (monomers or polymers). These responses were associated with distinct bacterial taxa, suggesting pronounced functional partitioning of these compounds in the Sea. Baltic Proper mesocosms amended with two different river loadings (forest versus agriculture river water) revealed a divergence in gene expression patterns between treatments during bloom decay. This was particularly true for genes in phosphorus and nitrogen metabolism, highlighting the importance and sensitivity of interaction effects between river- and phytoplankton-derived DOM in regulating bacterial activity responses to changes in precipitation-induced riverine runoff. In shipboard mesocosms in an Atlantic coastal upwelling system, we found significant changes in bacterioplankton transcription of hydrolyzing enzymes and membrane transporters from phytoplankton bloom development to senescence, primarily driven by phytoplankton-derived DOM and dissolved organic carbon dynamics. These responses differed substantially between bacterial orders, suggesting that functional resource partitioning is dynamically structured by temporal changes in DOM quantity and quality. Further analysis of these gene systems in a stratified fjord revealed pronounced divergence in transcription with depth and between bacterial taxa; moreover, transcription was more variable in the surface waters. This highlights the interplay between functional and physical partitioning of biogeochemical cycles. Collectively, the findings in this thesis contribute novel insights into the interdependency between prokaryotes and DOM by shedding light on the mechanisms involved in DOM cycling over ecologically relevant spatiotemporal scales
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