Mechanical response tissue analyzer for estimating bone strength

One of the major concerns for extended space flight is weakness of the long bones of the legs, composed primarily of cortical bone, that functions to provide mechanical support. The strength of cortical bone is due to its complex structure, described simplistically as cylinders of parallel osteons composed of layers of mineralized collagen. The reduced mechanical stresses during space flight or immobilization of bone on Earth reduces the mineral content, and changes the components of its matrix and structure so that its strength is reduced. Currently, the established clinical measures of bone strength are indirect. The measures are based on determinations of mineral density by means of radiography, photon absorptiometry, and quantitative computer tomography. While the mineral content of bone is essential to its strength, there is growing awareness of the limitations of the measurement as the sole predictor of fracture risk in metabolic bone diseases, especially limitations of the measurement as the sole predictor of fracture risk in metabolic bone diseases, especially osteoporosis. Other experimental methods in clinical trials that more directly evaluate the physical properties of bone, and do not require exposure to radiation, include ultrasound, acoustic emission, and low-frequency mechanical vibration. The last method can be considered a direct measure of the functional capacity of a long bone since it quantifies the mechanical response to a stimulus delivered directly to the bone. A low frequency vibration induces a response (impedance) curve with a minimum at the resonant frequency, that a few investigators use for the evaluation of the bone. An alternative approach, the method under consideration, is to use the response curve as the basis for determination of the bone bending stiffness EI (E is the intrinsic material property and I is the cross-sectional moment of inertia) and mass, fundamental mechanical properties of bone

A Decade of the Celler-Kefauver Anti-Merger Act

Corporations intent upon expanding via the acquisition route have had three statutory hurdles placed in their way by the Congress of the United States. As hurdles, the first two, the Sherman Act of 1890 and the Clayton Act of 1914, were failures. A judiciary which refused to give effect either to the language or intent of the acts nullified completely their usefulness as anti-merger weapons. The third hurdle, the Celler-Kefauver Amendment to the Clayton Act, was enacted in 1950. Relatively few judicial opinions have interpreted this act, new section 7, as it is called. It is clear, however, that it has little to fear in the way of a hostile judiciary or Federal Trade Commission. So far at least, delays which can be characterized only as incredible have been the sole serious problem for new section 7. Shortly before the turn of the century, a great merger movement began in the United States. Although the Sherman Act was the law of the land, effective action under it could be taken only after a monopoly had been achieved, if then. By 1914, it was clear to a majority of the Congress that, if the growing merger movement was to be checked, new legislation was needed. As enacted into law in 1914, section 7 of the Clayton Act contained a civil prohibition against the acquisition of stock of one corporation by another where the effect of the acquisition may be to substantially lessen competition between the corporation whose stock is so acquired and the corporation making the acquisition, or to restrain such commerce in any section or community, or tend to create a monopoly of any line of commerce