1,720,972 research outputs found
ECOLOGICAL AND PHYSIOLOGICAL MECHANISMS OF BIOLOGICAL RHYTHMS IN A POLAR-BREEDING SEABIRD
No full textBiological rhythms provide a mechanism for scheduling activity in predictably cyclic environments. During summer above the polar circle, the primary timing cue, the geophysical light-dark cycle, is highly attenuated or absent, yet some animals will exhibit diel rhythms of behavior and physiology under these conditions. How and why diel rhythms persist under this ‘polar day’ remains to be fully explored. This work builds on previous investigations of the proximate and ultimate mechanisms for maintaining biological rhythms during polar day by using an Arctic breeding seabird, thick-billed murre (Uria lomvia), that has sex-specific timing of activity above and below the polar circle during summer. Thick-billed murres’ sex-specific behavior when breeding was rhythmic during polar day with a period length of 24 h, and each sex’s colony attendance was antiphase to the other, resulting in an almost complete segregation of the sexes across the diel cycle. Corticosterone was not associated with these rhythms: it was invariant across the diel cycle and not associated with activity. Melatonin did not rise at the beginning of each sex’s quiescent phase, but did have variation in its diel profile suggesting a rise when the vertical, ENE-facing cliff where breeding occurs became shaded at midday, indicating that their melatonin response may be flexible. The sexes of thick-billed murres foraged at different times of day and to different depths across the diel cycle, which, in the context of the West Greenlandic food-web, suggested that the sexes forage on different prey when rearing chicks. Interestingly, the indirect measurements obtained from bird-borne data-loggers indicated the possible presence of diel vertical migration of their prey during polar day. Together this body of work adds to our understanding of biological rhythms in the polar environment
Impact of a noise-polluted urban environment on the song frequencies of a cosmopolitan songbird, the Great Tit (<em>Parus major</em>), in Denmark
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Guidance and background information for long-term monitoring of the Peregrine Falcon in South Greenland
No full textThe Peregrine Falcon has become a prominent indicator of environmental conditions across the world. In particular, the Peregrine has played a prominent role in detecting unintended side effects of chemical compounds accumulating in the environment. More recently, changing climatic conditions are also reflected in Peregrine populations and the falcons are included as focal species in Arctic Council's Circumpolar Biodiversity Monitoring Programme (CBMP) for the terrestrial environment. Long-term monitoring efforts are necessary to identify changes and the Peregrine monitoring in South Greenland, initiated in 1981, is rare in its coverage of more than four decades. In line with the 2022 Greenland National Research Strategy, it is now time for Greenland Institute of Natural Resources (GINR) to take over and institutionalise the monitoring – and ensure that the databases and know-how accumulated over decades is available for comparative studieslong into the future. Hence, this guidance document aims to support a continuation and possible expansion of the Peregrine Falcon monitoring so Greenland can continue to meet the commitments to CBMP, and maintain a sampling routine to help identify changes in occurrence of environmental pollutants, with implications for wildlife as well as humans on a global scale.The field efforts in South Greenland 1981-2023 have been conducted on a volunteer basis, or as part of Søren Møller’s limited allocation of research time from Roskilde University Library. We are grateful to the numerous dedicated volunteers who over the decades have shared the thrills of observing the magnificent Peregrines as well as endured rains and storms in dinghieson choppy waters or cramped into small tents.1 The field work has depended on invaluable logistical assistance from individuals and organisations in the survey area, and financial grants from a range of private and public foundations.2 Lastly, the process of transferring data and know-how to Greenland – and further exploring and developing monitoring opportunities of the Peregrine population – was made possible thanks to a generous support to GINR from Aage V. Charity Foundation 2023-2028
Remote time-lapse photography as a monitoring tool for colonial breeding seabirds:a case study using Thick-billed Murres (<em>Uria lomvia</em>)
No full textGoing 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
Data from: Sex-specific, inverted rhythms of breeding-site attendance in an Arctic seabird
No full textIn contrast to daily rhythms that are common in the presence of the geophysical light–dark cycle, organisms at polar latitudes exhibit many diel activity patterns during natural periods of continuous solar light or darkness (polar day and night, respectively), from 24 h rhythms to arrhythmicity. In Arctic Greenland (73.7° N, 56.6° W) during polar day, we observed breeding-site attendance rhythms of thick-billed murres (Uria lomvia; n = 21 pairs), a charadriiform seabird, which provide biparental care at the colony. We found that U. lomvia egg-incubation and chick-brooding attendance is rhythmic and synchronized to the geophysical day (mean period length [rhythm duration] ± 95% confidence interval = 24.13 ± 0.52 h). Individual pair members had temporally segregated, sex-specific colony-attendance rhythms that were opposite (inverted) to each other, and these sex-specific rhythms were prominent at the population level. Our results provide a basis for investigating circadian systems at polar latitudes and sex-specific parental-care strategies
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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