1,720,973 research outputs found
Homing in Sand Martin (Riparia riparia): factors that influence initial orientationJournal für Ornithologie, 135: 370.
No full textDistribution and abundance estimation of the domestic pigeon (Columba livia var. domestica) in the urban area of Piacenza
No full textLa consistenza numerica delle popolazioni di piccione domestico (Columba livia var. domestica) può arrivare in alcuni casi ad arrecare problemi tali da interferire con l’attività umana. In questo contesto, il Comune di Piacenza ha attivato un piano di monitoraggio della popolazione tramite il metodo del line transect sampling, finalizzato ad migliorare la gestione della specie nell’area urbana. L’area urbana del comune di Piacenza è stata suddivisa in due strati, omogenei sia architettonicamente che dal punto di vista di idoneità ambientale per il piccione domestico: il centro (2.92 km2) e la periferia (13.5 km2). Sono stati posizionati 60 transetti (20 in centro e 40 in periferia) sulla rete viaria lunghi circa 300 m ciascuno, percorsi entro le prime due ore dell’alba, segnando su un ortofoto ad alta definizione la corretta posizione di ogni individuo o gruppo di individui rilevato I dati sono stati georeferenziati tramite ArcGis 10.2. Il campionamento viene condotto due volte l’anno , in Febbraio e in Novembre, quando gli individui mostrano una limitata mobilità. I dati raccolti sono stati analizzati mediate il software distance 6.2, producendo le funzioni di contattabilità (una per il centro e una per la periferia) rappresentanti la diminuzione di probabilità di contattare l’animale. Le funzioni di contattabilità interpolate hanno consentito di stimare i parametri fondamentali per effettuare le stime di densità. Da esse emerge una densità significativamente maggiore di individui in centro rispetto che in periferia ma non tra periodi entro zona mentre non emerge nessuna differenza significativa nel comportamento gregario né tra zone né tra periodi (dimensione media dei gruppi tra 2.3 e 2.8 individui con limiti fiduciali al 95% sempre ampiamente sovrapposti). Le analisi condotte portano a stimare una presenza più consistente di piccioni in centro, pari a 6500-9000 (CV 20% circa) e di 7000-10000 (CV 12% circa) in periferia, per un totale di 17000 individui in Febbraio e 16000 in Novembre, con fluttuazioni stagionali limitate. Unitamente ad analisi di densità, si sta sviluppando un modello di distribuzione del piccione domestico all’interno dell’area urbana. Tale modello permetterà di definire la probabilità di presenza del piccione all’interno dell’area analizzando la relazione che lo lega con l’ambiente biotico ed abiotico, individuando quali caratteristiche determinano maggiormente la presenza della specie. Tale modello predittivo potrà essere utile per realizzare future attività di gestione della specie
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
L’occhione (Burhinus oedicnemus) nel Parco Nazionale dell’Alta Murgia: effetti della struttura di vegetazione e dell’uso del suolo sull’abbondanza della specie
No full textThe density of the Stone-curlew in the Alta Murgia National Park during the breeding season 2013. The estimated density was equal to 11 ind/Km2, with a minimum number of individuals between 164 and 172. The values of abundance of the species appear to be adversely affected by the height of the sward that is found mainly in the arable land with cereals, in pseudosteppe and uncultivated land, while in arable leguminous this parameter seems to affect positively the values of abundance. Currently one of the factors of threat are to be highlighted in the changes of land use, from arable crops to irrigated tree crops
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
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