Asymmetry and activity-related change in the male humerus

Some previous studies of activity-related change in the human skeleton have been of doubtful validity because specific changes have been related to particular tasks. Claims to establish such relationships have often concentrated on the development of entheses. Such work is marred by the incorrect assumption that muscles work in isolation in the performance of a single activity. In addition, normal skeletal asymmetry is often ignored, as is age and sex. In the present work, paired humeri of males from two medieval British sites, Norwich and Henry VIII's flagship, the Mary Rose, were compared using a series of measurements. Comparison of left and right sides demonstrated that humeral asymmetry decreases with age. Comparison of the sites showed that the Norwich males were more asymmetric than those from the Mary Rose. All asymmetries exhibited a right-sided dominance. The majority of the species is right-handed: the Norwich males followed this trend. The general lack of asymmetry in the Mary Rose males suggests that they were using their arms more equally. When left and right sides were compared directly, a new measurement of the greater tubercle (where three muscles insert) and measurement of the diameter of the head demonstrated that the Mary Rose males had significantly larger dimensions of the left shoulder than the Norwich males. These results extend earlier work, which had suggested a correlation between the use of heavy medieval longbows and os acromiale. Statistical comparison of the sites demonstrated that such work can indicate patterns of activity but not individual occupations.     

Displacement-Controlled Behavior of Asymmetrical Single-Story Building Models

Displacement controlled behavior is a feature of low to moderate seismicity areas where the peak displacement demand on structures could be limited despite significant structural strength and stiffness degradation. In this article, the extension of the displacement controlled phenomenon to torsionally unbalanced framing systems is investigated. It is shown that the displacement demand of critical elements within a building can be insensitive to changes in eccentricity and torsional stiffness properties. While torsional actions is a well-researched topic, the incorporation of displacement controlled phenomenon into the analysis is original and represents a new development.     

Temporal changes in Arikara humeral and femoral cross-sectional geometry associated with horticultural intensification

Humeral and femoral cross-sectional properties from three archaeological variants of the Arikara, an American Great Plains Indian tribe, were analyzed for temporal (16th to 19th centuries) changes in long bone architecture, asymmetry, and sexual dimorphism associated with intensification of horticulture during the late protohistoric and early historic periods. There were a number of significant changes in long bone, especially femoral, cross-sectional morphology and asymmetry among females through time that probably reflect increases in the workload necessary to produce surplus crops. Changes in long bone architecture among males are restricted to the humerus and may reflect a greater reliance on firearms. The pattern of sexual dimorphism also changes through time among the Arikara due to a combination of environmental (nutrition and disease) and mechanical factors.     

Robust Design of a Single Tuned Mass Damper for Controlling Torsional Response of Asymmetric-Plan Systems

A new robust design methodology to control the seismic performance of asymmetric structures equipped with a Single Tuned Mass Damper (STMD) is presented in this article. This design approach aims to control the seismic response of such systems by reducing both flexible-and stiff-edge maximum displacement. The dynamic problem has been investigated in the state space representation showing that the TMD works as a closed-loop feedback control action. A synthetic index to estimate the seismic performance of the main system has been defined by using H_∞ norm. Wide-ranging parametric numerical experimentation has been carried out to obtain design formulae for the STMD in order to minimize such a performance index. These formulae allow for a simple design of STMD position and stiffness to optimally control both translational and rotational motion components, whereas two mass devices are generally considered to improve the seismic performance of asymmetric structural systems The effectiveness and efficiency of the obtained design formulae have been tested by investigating the dynamic behavior of the asymmetric structure after being subjected to different recorded seismic inputs.     

Influence of Diaphragm Flexibility on Seismic Response of Unreinforced Masonry Buildings

The effects of diaphragm flexibility on the seismic response of low-rise unreinforced masonry buildings are examined using one-way stiffness- and strength-eccentric single-story systems subjected to unidirectional ground excitation. A wide range of diaphragm stiffnesses are considered. Results show that diaphragm flexibility can induce different effects depending on the configuration of the system and the level of diaphragm flexibility. When diaphragm is relatively stiff, amplified displacement demands can be imposed on the flexible side of the structure. When diaphragm is relatively flexible, peak displacements of in-plane loaded walls generally reduce. A diaphragm classification is developed to capture these salient effects.