1,720,965 research outputs found
Migration phenology of passerine birds in Latvia from 1984 to 2010
No full textŠis ir pirmais pētījums Latvijā par zvirbuļveidīgo putnu rudens migrācijas laika izmaiņām. Pētījumā izmantoti dati no divām ilglaicīgām putnu ķeršanas vietām – Lejasciema (1989–2010) un Papes (1984–2010).
Pētījuma rezultāti parāda, ka zvirbuļveidīgo putnu migrācijas izmaiņas ne vienmēr var saistīt ar klimata izmaiņām. Migrācijas tendences no Lejasciema visdrīzāk ir skaidrojamas ar lokālām izmaiņām biotopos. Dati no Papes ornitoloģisko pētījumu centra nav saistāmi ar lokālām migrācijas tendencēm, tādēļ tos var izskaidrot ar klimata izmaiņām. Visām četrām īsās distances gājputnu sugām (sarkanrīklītei, melnajam meža strazdam, zeltgalvītim un lielajai zīlītei) vērojams, ka migrācijas mediānais datums kļūst agrāks vidēji par 3–9 dienām. Tendence migrēt agrāk ir izteiktāka obligātajiem daļējiem migrantiem nekā fakultatīvajiem daļējiem migrantiem.Data from two long-term trapping sites Pape (1984–2010) and Lejasciems (1989–2010) is used for this study. This is the first study about changes of passerine bird autumn migration date in Latvia.
Tendencies of autumn migration delaying in Lejasciems has probably releated with local changes in forest biotops, not with climate changes. Only data from Pape can be used to describe migration phenology as response to changing climate. To all studied short distance migrant species (robin, blackbird, goldcrest and great tit) have tendency to migrate earlier about 3–9 days. To robin and blackbird, as obligate partial migrants, these tendencies are more significant than both facultative partial migrant species – goldcrest and great tit
Characteristics, changes in timing and demography of family Paridae autumn migration
No full textPētījuma rezultāti rāda, ka migrācijas norisē nav vērojamas būtiskas pārmaiņas. Tikai pelēkā zīlīte (Poecile montanus) uzrāda būtisku tendenci kādā no migrācijas posmiem migrēt agrāk. Arī starp mātītēm un tēviņiem nav būtisku atšķirību migrācijas norisē. Nedaudz ir palielinājusies lielo zīlīšu (Parus major) tēviņu proporcija rudens migrācijā. Veicot korelācijas analīzi starp vidējo gaisa temperatūru un migrācijas norisi bija redzams, ka meža zīlītei (Periparus ater) un pelēkajai zīlītei migrācijas norisi ietekmē vidējā gaisa temperatūra septembrī, bet lielajai zīlītei vidējā gaisa temperatūra oktobrī. Veicot fluktuāciju indeksa aprēķinus apstiprināta jau iepriekšējos pētījumos izvirzītā hipotēze, ka cekulzīlīte (Lophophanes cristatus) ir daļēji migrējoša suga, kura var veidot invāzijas.The research results show no overall changes in migration timing. Only willow tit (Poecile montanus) shows statistically significant trend to onset the migration earlier (for the first 5% of birds). No significant diferences were found in migration timing between males and females. However there is a slight increase in the proportion of great tit (Parus major) males in autumn migration. Correlation analysis using mean air temperature and the migration process showed that coal tit (Periparus ater) and willow tit migration time is affected by air temperature in September. Similarly, it appears that for great tits, average air temperature at the beginning of October is more important.
Additionaly fluctuations index calculations confirmed earlier scientific hypothesis that the crested tit (Lophophanes cristatus) is a partially migratory species with high probability to made an irruptive movements
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
Effects of individual traits vs. trait syndromes on assemblages of various herbivore guilds associated with central European Salix
No full textBiologické Centrum, Akademie Věd České Republiky http://dx.doi.org/10.13039/501100017273Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659National Science Foundation http://dx.doi.org/10.13039/10000000
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
Correction: Effects of individual traits vs. trait syndromes on assemblages of various herbivore guilds associated with central European Salix
No full textDispelling 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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