95 research outputs found
Trabecular and cortical bone structure of the talus and distal tibia in Pan and Homo.
No full textObjectives: Internal bone structure, both cortical and trabecular bone, remodels in response to loading and may provide important information regarding behavior. The foot is well suited to analysis of internal bone structure because it experiences the initial substrate reaction forces, due to its proximity to the substrate. Moreover, as humans and apes differ in loading of the foot, this region is relevant to questions concerning arboreal locomotion and bipedality in the hominoid fossil record.
Materials and methods: We apply a whole-bone/epiphysis approach to analyze trabecular and cortical bone in the distal tibia and talus of Pan troglodytes and Homo sapiens. We quantify bone volume fraction (BV/TV), degree of anisotropy (DA), trabecular thickness (Tb.Th), bone surface to volume ratio (BS/BV), and cortical thickness and investigate the distribution of BV/TV and cortical thickness throughout the bone/epiphysis.
Results: We find that Pan has a greater BV/TV, a lower BS/BV and thicker cortices than Homo in both the talus and distal tibia. The trabecular structure of the talus is more divergent than the tibia, having thicker, less uniformly aligned trabeculae in Pan compared to Homo. Differences in dorsiflexion at the talocrural joint and in degree of mobility at the talonavicular joint are reflected in the distribution of cortical and trabecular bone.
Discussion: Overall, quantified trabecular parameters represent overall differences in bone strength between the two species, however, DA may be directly related to joint loading. Cortical and trabecular bone distributions correlate with habitual joint positions adopted by each species, and thus have potential for interpreting joint position in fossil hominoids
Targeted Regeneration of Bone in the Osteoporotic Human Femur
No full textWe have recently developed image processing techniques for measuring the cortical thicknesses of skeletal structures in vivo, with resolution surpassing that of the underlying computed tomography system. The resulting thickness maps can be analysed across cohorts by statistical parametric mapping. Applying these methods to the proximal femurs of osteoporotic women, we discover targeted and apparently synergistic effects of pharmaceutical osteoporosis therapy and habitual mechanical load in enhancing bone thickness
Deverbal nominals in Kiswahili: Underspecification morphology and the lexicon
No full textThis study provides an explicit account of the lexical entries and rules required to generate five common types of Kiswahili nouns based on verbal roots and stems, as illustrated by the data below, all derived from -kata 'cut'. (UNFORMATTED TABLE OR EQUATION FOLLOWS)\vbox{\halign{#\hfil&&\enspace#\hfil\cr&a.&Action Nominals in -{\it o}:&{\it mkato/mikato\/}&`cut(s)'\cr&b.&Transitive Verbals in -{\it a}:&{\it mkata/wakata}&`cutter(s)'\cr&c.&Relic Agentives in -{\it i}:&{\it mkati/wakati}&`cutter(s)'\cr&d.&Productive Agentives in -{\it aji}:&{\it mkataji/wakataji}&`cutter(s)'\cr&e.&Patient Nominals in -{\it e}:&{\it mkate/mikate}&`lump(s), loaf/loaves'\cr}}(TABLE/EQUATION ENDS)Underspecification Theory as developed by Archangeli & Pulleyblank (1986) is adopted to aid in this descriptive task. A rigorous analysis of the Kiswahili phoneme set is provided in this framework, with underspecified and fully specified representations of all phonemes as well as explicit default and complement rules. A detailed account of various types of prefix allomorphy is included, both for inherent nouns and for derived nominals.The apparent simplicity of the data above is deceptive, even disregarding the account provided of the stem and suffix allomorphy associated with the Relic Agentives. Issues confronted in the description include semantic drift, blocking, percolation, questions of derivational source, and archaic roots. A particular focus of the study is to streamline the lexical entries by avoiding the explicit specification of redundant features of all kinds.An innovation in the research is the application of the principles of Underspecification Theory beyond the phonology to capture redundancies in and among the morphological, semantic, and syntactic features and representations. To develop and illustrate this approach, a set of four binary morphological features is proposed to capture the Kiswahili noun-class system. A further innovation is the use of Lexical Cross-References (LXRefs) which capture generalizations relating to morphological complexes while allowing redundant information to be filled in automatically.Made available in DSpace on 2011-05-07T13:59:06Z (GMT). No. of bitstreams: 2
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Previous issue date: 1990Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T15:01:35Z
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Changes in Body Measurements of Heifers at First Parturition
No full textAuthor Institution: Department of Dairy Science, Ohio Agricultural Experiment Station, Wooste
Wavelet Restoration of Medical Pulse-Echo Ultrasound Images in an EM Framework
No full textAbstract—The clinical utility of pulse-echo ultrasound images is severely limited by inherent poor resolution that impacts negatively on their diagnostic potential. Research into the enhancement of image quality has mostly been concentrated in the areas of blind image restoration and speckle removal, with little regard for accurate modeling of the underlying tissue reflectivity that is imaged. The acoustic response of soft biological tissues has statistics that differ substantially from the natural images considered in mainstream image processing: although, on a macroscopic scale, the overall tissue echogenicity does behave somewhat like a natural image and varies piecewise-smoothly, on a microscopic scale, the tissue reflectivity exhibits a pseudo-random texture (manifested in the amplitude image as speckle) due to the dense concentrations of small, weakly scattering particles. Recognizing that this pseudorandom texture is diagnostically important for tissue identification, we propose modeling tissue reflectivity as the product of a piecewise-smooth echogenicity map and a field of uncorrelated, identically distributed random variables. We demonstrate how this model of tissue reflectivity can be exploited in an expectation-maximization (EM) algorithm that simultaneously solves the image restoration problem and the speckle removal problem by iteratively alternating between Wiener filtering (to solve for the tissue reflectivity) and wavelet-based denoising (to solve for the echogenicity map). Our simulation and in vitro results indicate that our EM algorithm is capable of producing restored images that have better image quality and greater fidelity to the true tissue reflectivity than other restoration techniques based on simpler regularizing constraints. I
Automatic Segmentation and Discrimination of Connected Joint Bones from CT by Multi-atlas Registration
No full text- …
