309,416 research outputs found
Age-dependent health status and song characteristics in the barn swallow
No full textBird song has been hypothesized to evolve, partly, to signal health status of males, and song features should therefore correlate with parasite load. Immune function, parasitism, and secondary sexual characters can, however, differ between age classes, and any apparent relationship between song and parasite loads can be the result of systematic age effects. We tested for an age-dependent relationship between sexually selected characters and measures of parasitism in a Spanish population of the barn swallow Hirundo rustica. A comparison across age classes revealed that chewing lice load, song duration, mean peak amplitude frequency of songs, and tail length differed significantly between yearlings and adults. In a longitudinal analysis, we found significant evidence for mean peak amplitude frequency of songs, tail length and chewing louse parasitism, and a nonsignificant tendency for song duration to change with age of an individual. We found a significant association between song duration and chewing louse load and between hematocrit and peak amplitude frequency of the rattle, the typical harsh terminal syllable. In tests for associations between song traits and health status, while controlling for age, age and chewing louse load were independently related to song duration. We found a significant relationship between pairing success and song duration, implying that females may use this song trait in their choice of parasite-free males. Although the song of the barn swallow may provide information about both male age and parasite resistance, signaling of health status appears to be independent of age effects, in accordance with the theory of parasite-mediated sexual selection, suggesting that male signals can be used as reliable indicators of parasitism. Copyright 2005.age; barn swallow; bird song; chewing louse; hematocrit; sedimentation rate
Low Variation in the Polymorphic Clock Gene Poly-Q Region Despite Population Genetic Structure across Barn Swallow (Hirundo rustica) Populations
No full textPubMed ID: 22216124This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
The rocks of Kansas : with descriptions of new permian fossils
No full textby G.C. Swallow and F. Haw
Pink Cliffs from Swallow Park. Kane County, UT. 1922
No full textPhotograph showing Pink Cliffs from Swallow Park, Kane County, Utah, 1922. Photo from Herbert E. Gregory Book 8: 1915 - 1924
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Book Review: Swallow Summer
No full textSwallow Summer. Charles R. Brown. 1998. The University of Nebraska Press, Lincoln, NE. 371 pages. ISBN 0-8032-6145-4.
This book, Swallow Summer, is a popular account of the Browns fifteenth year at Cedar Point Biological Station in Keith County, Nebraska. Brown presents a daily log of the activities that he undertakes for the 1995 field season, describing the work supporting his research program. In the preface, Brown hopes Swallow Summer can explain his fascination with Cliff Swallows and why he enjoys his research. His intent is to describe the challenges, thrills, and frustrations that come with studying wild animals in the field and to tell the Cliff Swallow story
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Police cooperation in the European Union A comparative analysis of European level institutional and organisational developments and national level policies and structures
No full textSIGLEAvailable from British Library Document Supply Centre-DSC:DXN019566 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
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