1,721,001 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
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
Reproductive potential of the seed bank of plant communities on xerothermic sites
No full textFür die Bewertung der Reproduktion bzw. Erhaltung von xerothermen Vegetationseinheiten wurde die Zusammensetzung der Diasporenbanken von neun Pflanzengesellschaften in der Porphyrkuppenlandschaft des unteren Saaletals nordwestlich von Halle untersucht, die von halbnatürlichen Trockenund Halbtrockenrasen (Thymo-Festucetum, Filipendulo-Helictotrichetum, Galio-Agrostidetum, Festuco-Stipetum, Festuco-Brachypodietum) bzw. Zwergstrauchheiden (Euphorbio-Callunetum) bis hin zu mehr oder weniger ruderalisierten Grasdominanzbeständen (Festuca rupicola-Gesellschaft, ruderale Ausbildung des Arrhenatheretum elatioris, Convolvulo-Agropyretum) reichen. Sowohl die Anzahl der aus der Diasporenbank auflaufenden Keimlinge als auch die Artenzahl variierten zwischen den Gesellschaften stark und stiegen mit zunehmendem Hemerobiegrad deutlich an. Der Vergleich der im Boden tatsächlich enthaltenen Diasporen lag dabei deutlich höher, wobei deren Keimfähigkeit aufgrund von Dormanz gehemmt bzw. durch Beschädigungen bei einem Großteil nicht vorhanden war. Die Zusammensetzung der Diasporenbank ist von saisonalen Rhythmen abhängig. Im Herbstansatz liefen sowohl deutlich mehr Arten als auch Individuen auf, wobei im Frühjahr vor allem Arten, die eine langlebige Diasporenbank aufbauen, zu finden waren.
Der Vergleich zwischen Diasporenbank und Zusammensetzung der aktuellen Vegetation ergab bei den einzelnen Gesellschaften nur geringe Übereinstimmungen zwischen ca. 20 bis 40 %. Die Samenbanken werden in der Hauptsache von Arten mit einem langlebigen Diasporenbanktyp aufgebaut, während sich zahlreiche Xerothermrasenarten durch kurzlebige Diasporen auszeichnen. In den Samenbanken der Gesellschaften nimmt der Anteil der Arten mit transientem Diasporentyp mit steigendem Hemerobiegrad ab, wohingegen der Anteil mit long-term persistenten Diasporenbanktyp steigt. Der Anteil von Therophyten (sowohl Arten als auch Individuen) ist in den Samenbanken gegenüber der aktuellen Vegetation um das Doppelte bis Dreifache höher und stieg mit zunehmender Ruderalisierung an. Dies gilt ebenso für die Ruderalstrategen.
Das reproduktive Potential der Diasporenbanken von Xerothermrasen ist mit zunehmender Naturnähe als gering einzuschätzen, wobei die Diasporenbanken von Beständen auf historisch alten Standorten artenärmer sind als die von Gesellschaften auf jüngeren Standorten. Die Erneuerung bzw. Wiederherstellung von artenreichen Xerothermrasen ist deshalb ein schwieriger und langwieriger Prozess und sollte bei der Konzeption eines Pflegemanagements entsprechend berücksichtigt werden.In order to evaluate the reproduction capacity of xerothermic plant communities, it is necessary to know the species composition of the seed bank. The seed banks of nine xerothermic plant communities were studied in the porphyry landscape of the lower Saale valley northwest of Halle. The vegetation units exhibited different hemeroby levels and included nearly pristine, species-rich dry and semi-dry grassland communities (Thymo-Festucetum, Filipendulo-Helictotrichetum, Galio-Agrostidetum, Festuco-Stipetum, Festuco-Brachypodietum), dwarf-shrub heaths (Euphorbio-Callunetum), and grass-dominated communities (Festuca rupicola community, ruderal Arrhenatheretum elatioris, Convolvulo- Agropyretum). Both the number of species and the number of seedlings strongly varied between the plant communities and increased with higher degrees of hemeroby. As a result of the direct determination of diaspores, many more plant species and seeds were found than the number of both individuals and species which emerged in the germination experiment. However, most of the diaspores were dormant or damaged. The comparison of the seed banks follows a seasonal rhythm: many more species and individuals were found in autumn than in spring. The species germinating in spring form a long-term persistent seed bank.
The similarity between the seed bank and the vegetation is low (20 to 40 %). Species which are characterized by a long-term persistent seed bank are most common in the seed bank whereas most of the xerothermic species are characterized by a transient seed bank. The number of species with a transient seed bank type decreased in the communities with increasing degree of hemeroby, while the species with long-term persistent seed bank type increased. The number of therophytes (species and individuals) in the seed bank was two to three times higher than in the actual vegetation, and it increased with higher degree of hemeroby. Species with a ruderal strategy showed similar results. The reproductive potential of the seed banks of xerothermic vegetation with a higher degree of nativeness was low, and the seed bank of grassland communities on oldgrowth sites was species-poor. The renewal and re-establishment of species-rich, xerothermic plant communities is a long-term and difficult process which should be accorded more attention in management practice
Zur Keimungsbiologie acht ausgewählter kurzlebiger Ruderal- und Segetalarten
Get PDFPartzsch, M.: Germination biology of eight short-living ruderal and segetal species – Hercynia N. F.43 (2010): 149 –166.Knowledge on the germination behaviour of plant species allows to draw conclusions to be drawn ontheir associated regeneration capacity. Open field observations indicate that short-living species oftenproduce high numbers of seedlings. For this study we collected samples from eight species (Berteroaincana, Camelina microcarpa, Lepidium campestre, Medicago lupulina, Microrrhinum minus, Odontitesvulgaris, Thlaspi arvense and Trifolium arvense) which commonly occur throughout a climatic dryregion in central Germany in the vicinity of Halle/S. to investigate their germination behaviour underdifferent temperature and light conditions.A proportion of the mature seeds collected was used for an initial germination experiment while therest were buried in soil to ensure hibernation until the following experiment phase under similar conditionsthe following spring. The germination experiments were carried out under cold (8/4 °C), regular(20/10 °C) and hot (32/20 °C) temperature conditions and under an alternating light-dark regime (12h :12h). Thirty or forty batches of seeds (n = 4) were placed on filter paper in Petri dishes and kept permanentlymoist with de-ionized water. All germinated seeds (radicula being visible) were counted everytwo to three days. The experiments lasted 45 days and, after each experiment, the remaining seeds weretested for viability.In general, the germination percentage and velocity of the investigated species was highest under warmtemperature conditions, which corresponds with the optimum development period in any year. However,with the exception of Berteroa incana, germination in the year of harvest was surprisingly low. Theseeds of Berteroa incana were not dormant and germinated equally well after harvest and after hibernation.Berteroa incana belongs to the transient seed bank type. The dormancy of Camelina microcarpa,Lepidium ruderale and Microrrhinum minus was broken after hibernation, whereas Medicago lupulina,Odontites vulgaris, Thlaspi arvense and Trifolium arvense remained dormant. The first three speciesgerminated between 50 and 94 % at 32/20 °C in the second year and built up a short-term persistent seedbank. Germination of the four latter species was very low (approx. 40 % or lower), and after hibernation,their dormancy was not significantly broken, rendering their seed bank of the long-term persistence.Key words: Germination, dormancy, natural stratification, seed bank type, viabilityDie Hercynia publiziert Originalbeiträge mit dem Schwerpunkt Ökologie (mit ihren vielseitigen Aspekten der Biodiversität), Botanik, Zoologie, Geologie und Geografie, den anwendungsorientierten Bereichen des Natur- und Umweltschutzes, sowie der Land- und Forstwirtschaft
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