1,720,955 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
Light acclimation in intertidal seagrass : spatial and diurnal variations and the role of suspended sediments
No full textSeagrasses are the prevailing macrophytes along soft sediment coasts. One of the most important anthropogenic stressors for benthic macrophytes is increased suspended sediment loads and the attenuation of underwater light. Along many temperate coasts seagrasses occur predominantly in the intertidal but knowledge on the photophysiology of intertidal seagrasses is scarce. Studies focussing on the photoecophysiology of intertidal seagrasses are therefore urgently needed and the aim of this thesis was to fill this gap and provide some in-depth information on light acclimation mechanisms in intertidal seagrasses over diurnal and spatial scales. In a second step the impacts of suspended sediments on the underwater light regime and thus seagrass photosynthesis were examined. The first study assessed light adaptive strategies in a comparative analysis of the congeneric seagrass species Zostera muelleri and Zostera marina at two case study areas in New Zealand and Germany. The results showed marked fluctuations of photophysiology (maximum and effective quantum yield, non-photochemical quenching, cycling of xanthophyll cycle (XC) pigments) over daily and tidal cycles with a full xanthophyll cycle at both locations. At the New Zealand site we also observed significantly larger XC-pigment pool sizes in seagrass leaves sampled in a week when low tide coincided with noon. This very dynamic adjustment of xanthophyll pool sizes has not been previously reported for intertidal seagrasses and highlights their ability to adjust to strongly fluctuating irradiances in the intertidal. The high physiological plasticity of Zostera in light-saturated environments was also illustrated by the second study, which evaluated spatial differences in seagrass cover related to environmental conditions (light, temperature, sediment grain size distribution, and porewater nutrients) and differences in seagrass photosynthetic pigment composition and morphometry (above and below ground biomass, shoot length and leaf width, and percentage cover) at four sites in the meso-tidal estuarine lagoon of Tauranga Harbour, North Island, New Zealand. There were marked differences in pigment content and composition (as a marker of physiological plasticity), seagrass metrics as well as in environmental conditions. Our findings emphasize the high physiological plasticity and revealed also morphological plasticity of Zostera muelleri. Both studies underlined the general high light adaptation of intertidal seagrasses and their ability to thrive in fluctuating light environments. However, strong reductions in light conditions, e.g., through increased sediment loads entering coastal systems, may negatively affect seagrasses. Hence, the third study elucidated to what extent different sediment types (marine vs terrestrial) in different concentrations changed the underwater light regime in terms of overall photosynthetically active radiation (PAR) and the attenuation coefficient of downward irradiance of PAR (Kd) and quality (spectral composition). In a tank experiment the influence of different sediment types and concentrations were determined. In situ measurements of light quality and quantity, and suspended sediments (total suspended solids, TSS) at 12 sites in and outside of Tauranga Harbour, demonstrated that the lowest Kd and TSS values were found outside, and the highest within the harbour. Different scenarios for sediment loads, how they influence the underwater light regime and the potential for the vertical distribution of seagrass meadows are discussed. Relatively low Kd values of ~1 (as observed e.g., at the inner site of the lagoon) may already lead to maximum colonization depths of less than ~2 m, i.e., a limitation of seagrasses to intertidal habitats. This shows that current sediment loads and the resulting light conditions impair the growth of seagrasses beyond the intertidal at most sites. The (re)colonization of subtidal habitats may require significantly lower sediment loads entering the coastal zone. Therefore, authorities should consider an effective management on land and at the coast to keep anthropogenic sediment inputs at a minimum
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
Physiologische Reaktionen von Unterwuchsalgen nach Entfernen der Deckalgen in der Helgoländer Gezeitenzone.
No full textLichtanpassung in Seegräsern des Gezeitenbereichs : räumliche und diurnale Veränderungen und die Rolle von Sedimentfrachten
No full textSeagrasses are the prevailing macrophytes along soft sediment coasts. One of the most important anthropogenic stressors for benthic macrophytes is increased suspended sediment loads and the attenuation of underwater light. Along many temperate coasts seagrasses occur predominantly in the intertidal but knowledge on the photophysiology of intertidal seagrasses is scarce. Studies focussing on the photoecophysiology of intertidal seagrasses are therefore urgently needed and the aim of this thesis was to fill this gap and provide some in-depth information on light acclimation mechanisms in intertidal seagrasses over diurnal and spatial scales. In a second step the impacts of suspended sediments on the underwater light regime and thus seagrass photosynthesis were examined. The first study assessed light adaptive strategies in a comparative analysis of the congeneric seagrass species Zostera muelleri and Zostera marina at two case study areas in New Zealand and Germany. The results showed marked fluctuations of photophysiology (maximum and effective quantum yield, non-photochemical quenching, cycling of xanthophyll cycle (XC) pigments) over daily and tidal cycles with a full xanthophyll cycle at both locations. At the New Zealand site we also observed significantly larger XC-pigment pool sizes in seagrass leaves sampled in a week when low tide coincided with noon. This very dynamic adjustment of xanthophyll pool sizes has not been previously reported for intertidal seagrasses and highlights their ability to adjust to strongly fluctuating irradiances in the intertidal. The high physiological plasticity of Zostera in light-saturated environments was also illustrated by the second study, which evaluated spatial differences in seagrass cover related to environmental conditions (light, temperature, sediment grain size distribution, and porewater nutrients) and differences in seagrass photosynthetic pigment composition and morphometry (above and below ground biomass, shoot length and leaf width, and percentage cover) at four sites in the meso-tidal estuarine lagoon of Tauranga Harbour, North Island, New Zealand. There were marked differences in pigment content and composition (as a marker of physiological plasticity), seagrass metrics as well as in environmental conditions. Our findings emphasize the high physiological plasticity and revealed also morphological plasticity of Zostera muelleri. Both studies underlined the general high light adaptation of intertidal seagrasses and their ability to thrive in fluctuating light environments. However, strong reductions in light conditions, e.g., through increased sediment loads entering coastal systems, may negatively affect seagrasses. Hence, the third study elucidated to what extent different sediment types (marine vs terrestrial) in different concentrations changed the underwater light regime in terms of overall photosynthetically active radiation (PAR) and the attenuation coefficient of downward irradiance of PAR (Kd) and quality (spectral composition). In a tank experiment the influence of different sediment types and concentrations were determined. In situ measurements of light quality and quantity, and suspended sediments (total suspended solids, TSS) at 12 sites in and outside of Tauranga Harbour, demonstrated that the lowest Kd and TSS values were found outside, and the highest within the harbour. Different scenarios for sediment loads, how they influence the underwater light regime and the potential for the vertical distribution of seagrass meadows are discussed. Relatively low Kd values of ~1 (as observed e.g., at the inner site of the lagoon) may already lead to maximum colonization depths of less than ~2 m, i.e., a limitation of seagrasses to intertidal habitats. This shows that current sediment loads and the resulting light conditions impair the growth of seagrasses beyond the intertidal at most sites. The (re)colonization of subtidal habitats may require significantly lower sediment loads entering the coastal zone. Therefore, authorities should consider an effective management on land and at the coast to keep anthropogenic sediment inputs at a minimum
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
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
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