Histocomposition and geometry at the human mid-shaft femur.
Item
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Title
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Histocomposition and geometry at the human mid-shaft femur.
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Identifier
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AAI3024792
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identifier
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3024792
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Creator
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Goldman, Haviva Meira.
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Contributor
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Adviser: Timothy G. Bromage
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Anthropology, Physical | Biology, Anatomy
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Abstract
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Studies of cross-sectional geometry and histological structure of skeletal remains have been increasingly used for reconstructing functional adaptation within past human populations. Such research requires an understanding of modern human variability among ages, sexes, and populations to provide a comparative context. The central aims of this study were to determine the variability of selected material (i.e. histological composition) and structural (i.e. geometric shape) properties of bone within a sample of adult modern human mid-shaft femora, and to investigate interactions between these variables as related to biomechanical loading.;Using circularly polarized light and backscattered electron microscopy respectively, collagen fiber orientation and mineralization density were examined across entire cross-sections. These are both known to influence the mechanical properties of bone, and their spatial distributions are hypothesized to reflect loading during life. Measures of cross-sectional geometry were calculated, specifically the orientation of the axis of greatest bending rigidity (I max), to provide information about the regularity of bending loads at the femoral mid-shaft.;This study demonstrates extensive variability within each of the properties examined, both within and between age and sex groups. Significant differences in both the collagen fiber orientation and mineralization density are seen between regions of the cortex, indicative of non-random patterning, particularly within the youngest age group studied (age 25--44). However, contra Portigliatti-Barbos et al. (1983), no single pattern characterizes the human mid-shaft femur, or even a single age or sex group. Despite an average coincidence between the pattern of microstructural organization and the orientation of the I max axis, consistent with predicted bending forces at the midshaft, the vast majority of individuals in this sample show no relationship among these variables. Rather, these variables appear to act somewhat independently, resulting in different optimal configurations that may reflect an individual's unique life history. The heterogeneity identified even within a single adult human sample highlights the importance of exploring variability further before applying such research to archaeological or fossil samples. A better understanding of both the causes of this variability, and its extent both within and between populations may enhance our ability to understand the linkages between microstructure and functional adaptation.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
