1,721,045 research outputs found
morphomap: An R package for long bone landmarking, cortical thickness, and cross-sectional geometry mapping
Full text linkObjectives: This study describes and demonstrates the functionalities and application of a new R package, morphomap, designed to extract shape information as semilandmarks in multiple sections, build cortical thickness maps, and calculate biomechanical parameters on long bones. Methods: morphomap creates, from a single input (an oriented 3D mesh representing the long bone surface), multiple evenly spaced virtual sections. morphomap then directly and rapidly computes morphometric and biomechanical parameters on each of these sections. The R package comprises three modules: (a) to place semilandmarks on the inner and outer outlines of each section, (b) to extract cortical thicknesses for 2D and 3D morphometric mapping, and (c) to compute cross-sectional geometry. Results: In this article, we apply morphomap to femora from Homo sapiens and Pan troglodytes to demonstrate its utility and show its typical outputs. morphomap greatly facilitates rapid analysis and functional interpretation of long bone form and should prove a valuable addition to the osteoarcheological analysis software toolkit. Conclusions: Long bone loading history is commonly retrodicted by calculating biomechanical parameters such as area moments of inertia, analyzing external shape and measuring cortical thickness. morphomap is a software written in the open source R environment, it integrates the main methodological approaches (geometric morphometrics, cortical morphometric maps, and cross-sectional geometry) used to parametrize long bones
Exploring motion using geometric morphometrics in microscopic aquatic invertebrates: ‘modes’ and movement patterns during feeding in a bdelloid rotifer model species
Full text linkBackground: Movement is a defining aspect of animals, but it is rarely studied using quantitative methods in microscopic invertebrates. Bdelloid rotifers are a cosmopolitan class of aquatic invertebrates of great scientific interest because of their ability to survive in very harsh environment and also because they represent a rare example of an ancient lineage that only includes asexually reproducing species. In this class, Adineta ricciae has become a model species as it is unusually easy to culture. Yet, relatively little is known of its ethology and almost nothing on how it behaves during feeding. Methods: To explore feeding behaviour in A. ricciae, as well as to provide an example of application of computational ethology in a microscopic invertebrate, we apply Procrustes motion analysis in combination with ordination and clustering methods to a laboratory bred sample of individuals recorded during feeding. Results: We demonstrate that movement during feeding can be accurately described in a simple two-dimensional shape space with three main ‘modes’ of motion. Foot telescoping, with the body kept straight, is the most frequent ‘mode’, but it is accompanied by periodic rotations of the foot together with bending while the foot is mostly retracted. Conclusions: Procrustes motion analysis is a relatively simple but effective tool for describing motion during feeding in A. ricciae. The application of this method generates quantitative data that could be analysed in relation to genetic and ecological differences in a variety of experimental settings. The study provides an example that is easy to replicate in other invertebrates, including other microscopic animals whose behavioural ecology is often poorly known
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
Clines in Africa: does size vary in the same way among widespread Sub-Saharan monkeys?
No full textAim We characterize and compare patterns of clinal size variation amongdiverse widespread sub-Saharan monkeys with the aim of identifying common-alities and differences in biogeographical variation. Thus, we accurately quan-tify nonlinear clines in representatives of the main lineages of widespread sub-Saharan terrestrial and arboreal monkeys, and provide a crude numerical esti-mate of the strength of similarities across taxonomic groups.Location Sub-Saharan Africa.Methods Variations of skull centroid size, as a proxy for body mass, were modelledover sub-Saharan Africa within two terrestrial monkey species (Papio hamadryas andChlorocebus aethiops) and two arboreal monkey taxa (Procolobus (Piliocolobus) sp.,and the superspecies Cercopithecus nictitans – mitis) using inverse distance weighting,thin-plate splines and kriging. The model with the highest cross-validated accuracywas used to produce contour plots that visualized clines and predicted size at equallyspaced localities across overlapping areas of distribution ranges. Correlations amongthese predictions were used as a similarity measure among clines.Results Irrespective of phylogenetic distances and ecological differences, allgroups showed similarities in clinal size over central Africa: large animalsmostly live in and around the tropical forest of the Congo basin; size declinesrapidly towards the Horn of Africa and the coasts of Kenya and Tanzania. Sizealso tends to decrease in western Africa but clinal patterns in this region vary,with vervets exceptionally showing a size increase.Main conclusions Similarities in patterns of size across diverse monkey groupswere found. Nonetheless, complexity in clines and a degree of heterogeneity acrossgroups were evident, which is unlikely to be compatible with the exclusive effect onsize of a single main environmental factor. Primary productivity may be most sig-nificant in relation to the consistent observation of large sizes in and adjacent tothe central African tropical forest belt. Complex clines, such as those of Africanmonkeys, are difficult to compare visually and data collection from evenly sampledsets of localities, where all species of interest may be found, is often impractical orsimply not feasible for primates and other protected animals. The development ofimproved quantitative methods for the description and comparison of clines inmammals and other organisms is required
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
Skull form and evolution in Marmota (Rodentia, Sciuridae).
No full textA geometric morphometric analysis of the form of the marmot ventral cranium and mandible was carried out. Allometry was found to play an important role in shaping both these structures, and, although allometric trajectories were species-specific, similar shape changes were observed during ventral cranial and mandibular growth. Most of the ontogenetic shape changes occur in regions involved in the mechanics of mastication and bite. Sexual dimorphism is manifest mainly size. The interspecific comparison of ventral crania from all living marmot species produces results only partially congruent with those obtained for the mandible or with the marmot molecular phylogeny. The phylogenetic signal in the ventral cranium seems weaker than in the mandible, and the morphological clusters do not reflect evident size or ecological similarities. The ventral cranium could have limited evolutionary plasticity due to its complexity, and, thus, it may have retained plesiomorphic characters which contribute to mask the phylogenetic signal
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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