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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
Unraveling the function of Sll0944 in the regulation of carbon and nitrogen metabolism in Synechocystis sp. PCC6803
No full textInterlaboratory Reproducibility in Growth and Reporter Expression in the Cyanobacterium Synechocystis sp. PCC 6803
No full textUnraveling the function of Sll0944 in the regulation of carbon and nitrogen metabolism in Synechocystis sp. PCC6803
No full textUnraveling the Function of Sll0944 in the Regulation of Carbon and Nitrogen Metabolism in Synechocystis sp. PCC6803
Get PDFCyanobakterien sind als die Pioniere der oxygenen Photosynthese anerkannt und haben vor zwei Milliarden Jahren maßgeblich zur Umgestaltung der Erdat-mosphäre beigetragen. Im Laufe ihrer Evolution haben sie eine Vielzahl von Anpassungsmechanismen entwickelt, um sich an ständig wechselnde Umwelt-bedingungen zu gewöhnen. Ein zentraler Bestandteil dieser Anpassungen ist das regulatorische Netzwerk des Stickstoff-Regulations-Proteins PII. In dem nicht-diazotrophen Cyanobakterium Synechocystis sp. PCC 6803 steuert PII eine Vielzahl von Stoffwechselprozessen, die für die Aufrechterhaltung der Kohlenstoff- und Stickstoff-Homöostase essentiell sind. Die Regulation erfolgt über die Bindung von ATP, ADP und 2-Oxoglutarat, die je nach Energie- und Nährstoffverfügbarkeit als Signalmoleküle dienen. Unter Bedingungen eines ausgeglichenen Energiehaushalts und ausreichender Nährstoffversorgung ge-währleistet PII eine effiziente Bereitstellung von Aminosäurevorläufern und re-guliert die Fettsäuresynthese. Zudem hemmt es die Aktivierung des globalen Stickstoff-Transkriptionsregulators NtcA durch Bindung an das PII-interagierende Protein X.
Unsere Ergebnisse belegen eine entscheidende Rolle von PII bei der Regulation der Kohlenstoffspeicherung unter Stickstoffmangelbedingungen. Wir konnten zeigen, dass der PII-interagierende Regulator des Kohlenstoffstoffwechsels (PirC) die Umwandlung fixierten Kohlenstoffs von der Glykolyse zur Glykogen-synthese durch Hemmung der 2,3-Bisphosphoglycerat-unabhängigen Phos-phoglycerat-Mutase beeinflusst. Diese Hemmung wird durch PII reguliert, wobei die Bindung von PirC an PII von den intrazellulären Konzentrationen von ATP, ADP und 2-Oxoglutarat abhängt. Strukturanalysen deuten darauf hin, dass PirC spezifisch mit cyanobakterien-spezifischen Elementen der Phosphoglyce-rat-Mutase interagiert und somit deren Aktivität beeinflusst. Unsere Studie legt den Grundstein für die Entwicklung von Synechocystis sp. PCC 6803 als Chas-sisorganismus für die nachhaltige Produktion von Polyhydroxybutyrat (PHB) und anderen wertvollen Verbindungen. Durch gezielte genetische Modifikatio-nen konnten wir Stämme generieren, die bis zu 80% ihres Trockengewichts in Form von PHB speichern.Cyanobacteria are considered to be the inventors of oxygenic photosynthesis. Two billion years ago, they shaped the atmosphere by releasing oxygen. Through this time, they evolved various species with plenty of mechanisms to adapt to the constantly changing environment. Among all those mechanisms, some structures became established and further functions evolved around this basis. One of the most prominent examples of this is the regulatory network of the nitrogen-regulatory protein PII. In the non-diazotroph cyanobacterium Syn-echocystis sp. PCC 6803, PII regulates a plethora of reactions that maintain the Carbon/Nitrogen homeostasis. The regulations depend on the binding of either ATP or ADP during high energy and nitrogen availability and 2-oxoglutarate (2-OG) during low nitrogen availability. In a balanced proportion of energy and nutrition, PII ensures sufficient amounts of amino acid precursors by activating the phosphoenol pyruvate carboxylase and mitigating the fatty acid synthesis. It also binds the PII interacting protein X to prevent the activation of the global nitrogen transcriptional regulator NtcA. With the increase of 2-oxoglutarate, PII releases its binding partners, which cancels its regulations. It was suggested that PII also regulate carbon storage during low nitrogen availability.
This work clarified PII's involvement in carbon storage regulation during chloro-sis. The novel discovered that the PII interacting regulator of carbon metabo-lism (PirC) changes the direction of fixed CO2 from lower glycolysis to glycogen synthesis by inhibiting the 2,3-bisphosphoglycerate-independent phospho-glycerate mutase. PII regulates this inhibition by binding the PirC during high ADP and ATP and releasing it during high 2-OG levels. PirC mediates the inhi-bition by interacting with two cyanobacteria-exclusive structural elements with-in their phosphoglycerate mutase. Furthermore, the elements also have a strong influence on the activity of the enzyme. This work also created the basis on which Synechocystis sp. PCC 6803 can be edited to create a chassis for the sustainable production of polyhydroxybutyrate (PHB) or other metabo-lism-derived valuable compounds. A strain derived from this work produced 80 % PHB of their cell dry mass
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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