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Angle Data (angle + data)
Selected AbstractsThe contribution of limb bone fracture patterns to reconstructing early hominid behaviour at Swartkrans cave (South Africa): archaeological application of a new analytical methodINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 4 2005T. R. Pickering Abstract Recently, Alcántara García et al. (in press) presented a new method and criteria for distinguishing between fractures imparted by hominid hammerstone percussion and carnivores chewing on ,green' limb bones of ungulates. The method uses a combination of fracture plane and fracture angle data that are useful for elucidating the relative role of hominids in the accumulation of prehistoric archaeofaunas, especially when employed in concert with other classes of taphonomic data. We briefly summarise the method and apply it to the ungulate limb bone subassemblage from Swartkrans Member 3, a c. 1.0 million year old site from South Africa that preserves Early Stone Age lithic artefacts, hominid fossils, and an abundant mammalian fauna with cutmarked, hammerstone-percussed and burned bone specimens. Results of the fracture pattern analysis corroborate indications from other lines of taphonomic data that there was minimal carnivore,hominid interdependence in the formation of the fauna, and that carnivores were probably responsible for the majority of the bone collection in Member 3. However, we also document a significant hominid influence on assemblage formation, a finding that expands and refines our understanding of large animal carcass foraging by hominids in southern Africa during the early Pleistocene. Copyright © 2004 John Wiley & Sons, Ltd. [source] A robot-assisted study of intrinsic muscle regulation on proximal interphalangeal joint stiffness by varying metacarpophalangeal joint positionJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2006Zong-Ming Li Abstract The tightness of intrinsic hand muscles is a common cause of finger joint stiffness. The purposes of this study were to develop a robot-assisted methodology to obtain torque,angle data of a finger joint, and to investigate the regulation of the intrinsic muscles on finger joint stiffness. Our robot system features the integration of a low payload robot arm, a controller, and a force/torque transducer. The system provided highly reproducible torque,angle curves. Torque,angle data of the proximal interphalangeal joint with the metacarpophalangeal joint at 0 and 60 degrees were obtained from eight asymptomatic hands. The torque,angle curve shifted with the position of the metacarpophalangeal joint. As the metacarpophalangeal joint flexion angle changed from 60 to 0 degrees, the equilibrium of the proximal interphalangeal joint increased more than 20 degrees, and joint stiffness increased more than 50%. The dependence of the stiffness of the proximal interphalangeal joint on metacarpophalangeal joint position supports the regulatory role of the intrinsic muscles on finger joint mechanics. This regulatory mechanics is likely amplified in hands with intrinsic muscle tightness, justifying the commonly used Bunnell Intrinsic Tightness Test. © 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:407,415, 2006 [source] The Dynamic Interaction of Water with Four Dental Impression Materials During CureJOURNAL OF PROSTHODONTICS, Issue 4 2009Dariush Hosseinpour PhD Abstract Purpose: The purpose of this work was to investigate the interaction of water with four different dental impression materials: Aquasil (Ultra XLV Type 3), Take 1 (Wash Regular Set), Genie (Light Body, Standard Set), and Impregum Garant (Soft Light Bodied Consistency). Materials and Methods: Apparent contact angles of de-ionized water made against thin horizontal sample films of the different materials under different conditions were measured from analysis of profile images of symmetrical sessile drops of water placed on the sample films using a Model FTÅ200 dynamic drop shape analysis system, which included a JAI M30 high speed CCD camera combined with a zoom microscope. Data were taken for specimens of dry ages (times following mixing) from a minimum of 20 seconds up to 1220 seconds. Imaging was started before the initial water/impression material contact, and lasted for at least 420 seconds in each case. The interval at the beginning of each run was 0.033 second, and then increased by a factor of 1.012 to the end. During the initial 3 seconds following the drop deposition, the drop's shape oscillated due to inertial effects, so apparent contact angle data during this period were neglected in all cases. All measurements were made at room temperature. The drops were enclosed in a humidified chamber that suppressed evaporation. All data were repeated at least five times, and results were analyzed where appropriate using one-way ANOVA. Microscopic images of the water/impression material interactions for fresh (uncured) materials were acquired to reveal the destructive interactions that resulted from such contact. Finally, surface tension measurements were made of water that had been contacted with material of varying dry age using the pendant drop method capability of the drop shape analysis system. These helped to assess the origin of hydrophilicity development for the different materials. Results: For short curing times (dry ages), water showed a destructive effect on the integrity of all of the impression materials, as evidenced by the formation of a crater beneath the water drop and a scum of material at its surface. These effects diminished with dry age until a critical curing time was reached, beyond which such destructive interactions were no longer detectable. These critical curing times were determined to be 80, 140, 110, and 185 seconds for Aquasil, Take 1, Genie, and Impregum, respectively. The initial contact angle following the respective critical curing time was lowest for Impregum, at 66°; while values for Aquasil, Genie, and Take 1 were 93°, 104°, and 110°, respectively. Beyond the critical curing times for the different materials, different degrees of hydrophilicity were observed. Aquasil showed the lowest final contact angle (<10°), with Impregum, Take 1, and Genie showing 31°, 34°, and 40°, respectively. Measurements of the surface tension of water after contact with the different materials suggested that for Aquasil, hydrophilicity appears to be developed through the leaching of surfactant from the material, whereas for Impregum, Take 1, and Genie, hydrophilicity is developed at least in part through a change in surface structure in contact with water. Impregum and Aquasil materials of dry ages well beyond the critical curing time exhibited a stick-slip behavior in their interline movement or contact angle evolution. This was believed to be due to the slowness in the leaching of surfactant (in the case of Aquasil) or the re-orientation of unleachable surface groups (in the case of the other materials) in comparison to the inherent kinetics of water drop spreading. Conclusions: All materials investigated in the fresh, uncured state showed qualitative decomposition when put in contact with water through the formation of a crater beneath the water drop and a scum of material at its surface. These effects diminished with curing time until beyond a critical value, no such effects were evident. The initial hydrophilicity of the materials as determined by the contact angles obtained at their respective critical dry ages was greatest for Impregum. Beyond the critical curing time, different degrees of hydrophilicity were observed, with Aquasil showing the lowest final contact angle. [source] A method for quantifying rotational symmetryNEW PHYTOLOGIST, Issue 4 2007Frank M. Frey Summary ,,Here, a new approach for quantifying rotational symmetry based on vector analysis was described and compared with information obtained from a geometric morphometric analysis and a technique based on distance alone. ,,A new method was developed that generates a polygon from the length and angle data of a structure and then quantifies the minimum change necessary to convert that polygon into a regular polygon. This technique yielded an asymmetry score (s) that can range from 0 (perfect symmetry) to 1 (complete asymmetry). Using digital images of Geranium robertianum flowers, this new method was compared with a technique based on lengths alone and with established geometric morphometric methods used to quantify shape variation. ,,Asymmetry scores (s) more clearly described variation in symmetry and were more consistent with a visual assessment of the images than either comparative technique. ,,This procedure is the first to quantify the asymmetry of radial structures accurately, uses easily obtainable measures to calculate the asymmetry score and allows comparisons among individuals and species, even when the comparisons involve structures with different patterns of symmetry. This technique enables the rigorous analysis of polysymmetric structures and provides a foundation for a better understanding of symmetry in nature. [source] | ||||||||||