1,721,103 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
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
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
Primary producers and future ocean scenarios : effect of environmental change on biomolecular composition of phytoplankton and transference to higher trophic levels
Full text linkAn increasing body of research emphasizes that various biological processes in marine organisms are affected due to the uptake of anthropogenic atmospheric CO2 by the ocean in a process termed as ocean acidification (OA). The magnitude and direction of OA effects varies greatly among species and genotypes, highlighting different capabilities to adapt to increasing CO2. Direct OA impacts can be expected in the biochemical and elemental composition of primary producers (PP), which may be transferred to higher trophic levels, while indirect impacts can derive from altered trophic interactions as OA can modify plankton community composition. Fatty acids (FA) are the main component of lipids and cell membranes, with polyunsaturated fatty acids (PUFA) having additional important physiological and metabolic roles. Phytoplankton is the main source of essential biomolecules for heterotrophs as they cannot synthesize them de novo. Transference of organic essential macromolecules, in particular PUFA from phytoplankton-to-zooplankton-to-fish is a key factor influencing the life cycle of many organisms including humans. In the present work was investigated how OA influences the food quality of primary producers in terms of their fatty acid makeup at specie and community level, and how these OA-driven changes in the algae affect the fatty acid profile and life cycle of consumers. A combination of short- and long-term experiments on individual algal species, interaction between a single primary producer and one consumer, and natural plankton communities encompassing several producers and consumers were conducted in laboratory and natural conditions. In the short-term experiments at species level, the first and second laboratory study showed that CO2 can affect the biochemical composition of the diatoms Thalassiosira pseudonana and Cylindrotheca fusiformis, reducing their PUFA content; additionally the second diatom showed a reduced amount of amino acids. The interaction between a single primary producer and one consumer showed that when T. pseudonana cultured under high CO2 was used to feed the copepod Acartia tonsa, it affected their FA composition, severely impaired development and egg production rates. This demonstrated that a direct OA-driven shift in algal food quality can influence the reproduction success of upper trophic levels. At the community level, the third study conducted in a North Sea natural plankton assemblage subjected to a CO2 gradient showed that OA can modify phytoplankton community structures by favoring small phytoplankton cells with a comparatively low PUFA content. This community shift reduced PUFA content in primary producers was linked to a gradual PUFA decline in the dominant copepod species Calanus finmarchicus. In contrary, the fourth study revealed that the natural plankton community of the Baltic Sea experienced small differences in the algal community composition between CO2 treatments. The PUFA profile of the PP was influenced by phosphorus availability in the mesocosms, which was reflected by the PUFA composition of the copepod Acartia tonsa and Eurytemora affinis, but showed no significant CO2-related changes. This indicates that OA can affect the plankton community composition and its associated PUFA content, however this effect is lower in environments where communities are exposed to natural occurring high CO2 fluctuations like in the Baltic Sea, and that other essential nutrients have a stronger influence in the algal FA profile when present in limited amounts. In the long term experiments at species level, the fourth study determined that the coccolithophore Emiliania huxleyi and the diazotrophic cyanobacterium Trichodesmium sp. cultured over a thousand generations at high CO2 conditions showed a change in their FA content and composition. The FA profile of both algae presented a differentiate adaptation to high CO2 and particularly PUFA, which have metabolic functions in the cells, displayed evidence of adaptive evolution in both algae. These results highlight the diversity of OA responses among single plankton species and communities and that changes in biomolecular composition at the base of the marine food web are transferred to primary consumers. The thesis also highlights that the magnitude and direction of CO2-effects likely depends on the CO2 conditions and fluctuations the organisms are adapted to
Pelagic community responses to changes in N:P stoichiometry in the Eastern Tropical Atlantic and Pacific
Full text linkRecent studies indicate that the tropical ocean is losing oxygen. This becomes crucial in regions adjacent to eastern boundary currents, as the productivity of these systems is already accompanied by oxygen minimum zones (OMZ) at depth below the photic zone. The extent of low oxygen water masses influences dissolved nutrient inventories, as oxygen-sensitive nitrogen (N) loss processes such as denitrification and anammox are enhanced and inorganic phosphorus is remobilized from sediments, resulting in low N:P of upwelled waters, especially in the East Pacific. The present study aimed to investigate the impact of changing N and P supply on the pelagic primary producers and consumers in the photic zone. To achieve this, nutrient manipulation experiments were conducted in the eastern tropical Pacific and Atlantic Ocean using a newly designed shipboard mesocosm setup. Results demonstrated that in these regions, where N:P is generally below the canonical Redfield ratio of 16, inorganic N is the key control of bulk productivity regardless of the amount of P added, especially of bloom-forming diatom species and ciliate consumers (chapter I and II). However, the response of individual species and pools of organic matter was found to be more complex. For example, Phaeocystis globosa and Heterosigma sp. clearly benefitted from high P-levels (chapter I). Both algal groups are considered of inferior quality to mesozooplankton consumers compared to diatom-dominated assemblages. The observation that the relative content of unsaturated fatty acids in the particulate matter was positively related to diatom biomass (chapter I) is a second clue that decreasing N flux to the surface ocean impacts food web productivity. However, the RNA/DNA ratio, as a proxy for nutritional condition, did not change in the copepod Undinula vulgaris when fed on the manipulated mesocosm community over a period of three days (chapter II). The results of the nutrient manipulation experiments off Peru and West Africa were surprisingly similar, despite the fact that the North Atlantic features excess N at depth due to N2-fixation and the lack of suboxic conditions that would promote N-loss processes. Furthermore, pigments characteristic for cyanobacteria indicated that diazotrophs were increasing in those mesocosms that had received a higher initial N load (chapter I and II), which contradicts the common understanding that diazotrophs would benefit from excess P. In addition, we observed that the N:P excretion ratio of copepods (U. vulgaris) feeding on the manipulated mesocosm assemblage was influenced by the N:P of bulk particulate organic matter (PON:POP), which in turn responded directly to the manipulation ratios (chapter II). In order to survey the natural variability in N and P excretion rates in the Eastern Tropical North Atlantic, measurements were conducted in shipboard incubations at several stations on three epipelagic copepod species (chapter III). Within species, excretion N:P was positively related to PON:POP at the respective station; however, the low number of stations sampled and the variability of PON:POP within the upper 150 m hampered the establishment of a functional relationship. The N:P excretion ratio was consistently higher in the carnivorous Euchaeta marina compared to the omnivorous U. vulgaris and Scolecithrix danae. This can be attributed to the rather rigid N:P stoichiometry of zooplanktonic prey items of E. marina in contrast to the unicellular food items of the other two species (such as diatoms, dinoflagellates and heterotrophic protists) with more variable N:P. A further question addressed in this study was to what extent atmospheric N sources (N2-fixation and dust) are contributing to secondary production in the Eastern Tropical North Atlantic, and how this contribution is related to the vertical flux of dissolved inorganic nitrogen (chapter IV). We used zooplankton stable nitrogen isotopes (15N) to estimate the relative contribution of atmospheric N sources and found that it ranged from less than 20% off the West African coast to 60% in the open ocean (Guinea Dome region), and was positively related to the depth of the nitracline
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
