Browsing by Subject "Cluster Analysis"

Now showing 1 - 2 of 2
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    Aiming at a data driven definition of volunteer types: The key to improved volunteer management practices
    (International Society for Third-Sector Research (ISTR), 2014) Walk, Marlene; Willems, Jurgen
    Due to the huge heterogeneity of volunteering, generalizability of context specific findings from the literature regarding volunteer management practices is often limited. Furthermore, it seems that practitioner recommendations are consequently often too narrow or at times contrasting. To deal with this gap, we aim at a data driven approach to cluster volunteers into more homogeneous types, in order to enable (a) comparability of various volunteer contexts, and (b) differentiation of volunteer management strategies. Therefore, we apply an exploratory factor analysis, a cluster analysis and a canonical correlation analysis on a representative nationwide survey in Germany regarding volunteering behavior. Findings are however not robust and not suitable for further substantial interpretation, as the multivariate characteristics of the constructs probed for in the German Survey on Volunteering (GSV) are of limited quality (at least for our statistical analysis). Hence, we clarify the value of more elaborate questions in future large-scale data collection, and we discuss the remaining trade-off in the literature regarding generalizable but limited findings, versus more robust but context specific findings.
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    Characterization of the juvenile green turtle (Chelonia mydas) microbiome throughout an ontogenetic shift from pelagic to neritic habitats
    (PLOS, 2017-05-11) Price, James T.; Paladino, Frank V.; Lamont, Margaret M.; Witherington, Blair E.; Bates, Scott T.; Soule, Tanya; Biology, School of Science
    The gut microbiome of herbivorous animals consists of organisms that efficiently digest the structural carbohydrates of ingested plant material. Green turtles (Chelonia mydas) provide an interesting model of change in these microbial communities because they undergo a pronounced shift from a surface-pelagic distribution and omnivorous diet to a neritic distribution and herbivorous diet. As an alternative to direct sampling of the gut, we investigated the cloacal microbiomes of juvenile green turtles before and after recruitment to neritic waters to observe any changes in their microbial community structure. Cloacal swabs were taken from individual turtles for analysis of the 16S rRNA gene sequences using Illumina sequencing. One fecal sample was also obtained, allowing for a preliminary comparison with the bacterial community of the cloaca. We found significant variation in the juvenile green turtle bacterial communities between pelagic and neritic habitats, suggesting that environmental and dietary factors support different bacterial communities in green turtles from these habitats. This is the first study to characterize the cloacal microbiome of green turtles in the context of their ontogenetic shifts, which could provide valuable insight into the origins of their gut bacteria and how the microbial community supports their shift to herbivory.