1,720,957 research outputs found
Investigating Variation in Trabecular and Cortical Bone Structure Due to Mobility Impairment: A Study of Reduced Loading
No full textBone is a dynamic tissue that responds to its mechanical environment via changes in mass and architecture, a concept known as bone functional adaptation. Since mechanical usage influences trabecular and cortical architecture and density, reduced ambulatory ability should be reflected in these structures of the limb bones. Anthropological research has primarily focused on bone adaptation due to overuse and habitual loading, while few studies have addressed the effects of reduced loading. Previous research on bone response to reduced loading and disuse mainly uses experimental animal models or clinical studies that lacks the resolution necessary to study certain bone microstructure. This research investigates the effects of mobility impairment on human long bone trabecular and cortical structure using high-resolution micro-computed tomography (micro-CT). In particular, this study examines differences and patterns in the bone microstructure depending on whether the condition that caused mobility impairment involved retention or loss of muscle function, whether there is a correlated effect in the humerus as a non-weight bearing bone, and how bone structural changes associated with aging compare to those related to mobility impairment. Understanding the patterns expressed from an inferred reduced loading in individuals who have experienced mobility impairment is important to correctly interpreting various loading signatures, and in turn to potentially identify unknown individuals who experienced impaired mobility during life. This could allow for such conditions to be recognized in individuals in a forensic context to aid in identification of unknown human remains or in bioarchaeological contexts, greatly adding to demographic, paleopathological and biocultural insights about a population or individual.
Both the left and right femora and humeri of sixty-nine individuals who experienced mobility impairment during life and one femur and humerus of sex and age-matched full mobility individuals were micro-CT imaged. Trabecular architecture was quantified using multiple geometrically homologous spherical volumes of interest (VOIs) positioned within each joint head. The trabecular parameters bone volume fraction (BV/TV), trabecular thickness (Tb.Th) and spacing (Tb.Sp) were extracted for each VOI. In addition, these VOIs were used to create mean trabecular parameter visualizations across the joint surface to view consistent patterns. Single spherical central VOIs were additionally extracted from each joint head for assessment of variation captured within a single more easily reproducible region for purposes of practical application. Cortical bone slices at femoral midshaft and subtrochanteric and humeral distal 35% were analyzed for cross-sectional area and geometric properties.
Results demonstrate that individuals who experienced mobility impairment during life have significantly less femoral BV/TV and Tb.Th and greater Tb.Sp. than the full mobility individuals. In the humerus, there is greater Tb.Th in the mobility impairment samples, although no significance in BV/TV. This indicates use of the upper limbs more extensively and in more varied ways to compensate for the lower limb impairment. The cortical bone results demonstrate femoral bone loss with increased medullary cavity area along with observable porosity of the cortical area and trabecularization of the endosteal surface in the mobility impairment sample. The amount of time of impairment and groupings of the mobility impairment conditions were investigated with varied results, indicating an individualized response to bone loss due to mobility impairment. Although similar in pattern, age-related bone loss exhibits no change to femoral trabecular thickness, while trabecular thinning is observed due to mobility impairment. Additionally, assessing the trabecular and cortical bone in combination in both the femur and humerus can help to distinguish bone loss and structural changes due to mobility impairment as opposed to age-related changes.
The results of this study demonstrate that the inferred reduction of biomechanical loading on the lower limbs of individuals who experienced mobility impairment during life is reflected in their femoral trabecular and cortical bone with varied results in the humeri depending on the mobility impairment condition. This research helps to improve our understanding of bone functional adaptation as associated with reduced loading and disuse. Furthermore, it has implications for detecting and diagnosing mobility impairment in unknown human skeletal remains. In a bioarchaeological context this could add to biocultural insights about an individual or population and within the forensic context provide important information that could aid in identification.Anthropolog
The effect of mobility impairment in cortical and trabecular structure
No full textNo abstract prepared.Anthropolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
