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  • 1
    Electronic Resource
    Electronic Resource
    Noninvasive measures of bone bending rigidity in the monkey (M. nemestrina) (1979)
    Springer
    Calcified tissue international 27 (1979), S. 109-115 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Bending rigidity ; Disuse atrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The in vivo bending rigidity and bone mineral content of monkey ulnae and tibiae were measured. Bending rigidity in the anteroposterior plane was measured by an impedance probe technique. Forced vibrations of the bones were induced with an electromechanical shaker, and force and velocity at the driving point were determined. The responses over the range of 100–250 Hz were utilized to compute the bending rigidity. Bone mineral content in the cross section was determined by a photon absorption technique. Seventeen male monkeys (Macaca nemestrina) weighing 6–14 kg were evaluated. Repeatability of the rigidity measures was 4%. Bone mineral content was measured with a precision of 3.5%. Bending rigidity was correlated with the mineral content of the cross section,r=0.899. Two monkeys were evaluated during prolonged hypodynamic restraint. Restraint produced regional losses of bone most obviously in the proximal tibia. Local bone mineral content declines 17 to 24% and the average bending rigidity declines 12 to 22%. Changes in bones leading to a reduction in mineral content and stiffness are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441171
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Tibial changes in experimental disuse osteoporosis in the monkey (1983)
    Springer
    Calcified tissue international 35 (1983), S. 304-308 
    Details
    ISSN: 1432-0827
    Keywords: Immobilization ; Bone strength ; Resorption ; Recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We studied the mechanical properties and structural changes in the monkey tibia with disuse osteoporosis and during subsequent recovery. Bone bending stiffness was evaluated in relationship to microscopic changes in cortical bone and Norland bone mineral analysis. Restraint in the semireclined position produced regional losses of bone most obviously in the anterior-proximal tibiae. Following 6 months of restraint, the greatest losses of bone mineral in the proximal tibiae ranged from 23% to 31%; the largest changes in bone stiffness ranged from 36% to 40%. Approximately 8 ½ months of recovery were required for restoration of normal bending properties. However, even after 15 months of recovery, bone mineral content did not necessarily return to normal levels. Histologically, resorption cavities in cortical bone were seen within 1 month of restraint; by 2 ½ months of restraint there were large resorption cavities subperiosteally, endosteally, and intracortically. After 15 months of recovery, the cortex consisted mainly of first-generation haversian systems. After 40 months, the cortex appeared normal with numerous secondary and tertiary generations of haversian systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405051
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  • 3
    Electronic Resource
    Electronic Resource
    Acoustic measurements of stress fields and microstructure (1980)
    Springer
    Journal of nondestructive evaluation 1 (1980), S. 67-77 
    Details
    ISSN: 1573-4862
    Keywords: stress fields ; microstructure ; J integral ; stress intensity factor ; harness acoustic velocity ; acoustic elasticity ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A very precise system for measuring two-dimensional velocity fields in solid samples has been used for nondestructive measurements of both externally applied and residual inhomogeneous stresses in solids,J integrals, stress intensity factors of cracks, and hardness of quenched steel. The longitudinal velocity measurement is based on precise determination of the propagation transit time through the stressed solid specimen using a small diameter, water-coupled acoutic transducer, which is scanned mechanically over the sample. Changes in velocity are then related to changes of stress in the sample by the theory of acoustoelasticity. Similar measurements show a high degree of correlation between longitudinal velocity changes and changes in microstructure in steel samples. Applications to problems of solid mechanics and material science illustrate the utility of this nondestructive measuring technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566232
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  • 4
    Electronic Resource
    Electronic Resource
    Fully stressed thickness profile design at discontinuities of axisymmetric shells (1994)
    Springer
    Structural and multidisciplinary optimization 7 (1994), S. 199-205 
    Details
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In a shell structure, the discontinuity at the intersection of two shells causes stress concentration. This paper presents a procedure which couples the Curvature Function Method with the FAST1 structural shell analysis program to find a fully stressed thickness profile which keeps the stress at the discontinuities at the nominal stress value. The Curvature Function Method is a zero-order method that requires only stress values along the shell, not gradients of the stresses with respect to the design variables, and the resulting thickness profile has C2 continuity. Although the method is independent of the structural analysis program used to determine stress values, Fast1 provides a particular advantage because it allows the user to model complex shells with only a few large shell elements and still retain a sufficiently accurate solution. Thus both preparation and computation times are reduced substantially. Convergence of different initial designs to one final design using this procedure is demonstrated for a cylinder-cone intersection problem. This procedure is also applied to two other shell models with multiple discontinuities to find their fully stressed thickness profiles. The procedure presented in this paper provides a practical technique and tool to aid the design engineer, although the fully stressed design may not be the theoretically optimal design of minimum weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01742467
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  • 5
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    The discordant eardrum (2006)
    National Academy of Sciences
    Details
    Publication Date: 2006-12-14
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 6
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    Acoustoelastic imaging of stress fields (1979)
    American Institute of Physics
    Details
    Publication Date: 1979-04-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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  • 7
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    Effects of chair restraint on the strength of the tibia in rhesus monkeys (2001)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: To determine the effects of the relative inactivity and unloading on the strength of the tibias of monkeys, Macaca mulatta, we used a non-invasive test to measure bending stiffness, or EI (Nm2), a mechanical property. The technique was validated by comparisons of in vivo measurements with standard measures of EI in the same bones post-mortem (r2 = 0.95, P 〈 0.0001). Inter-test precision was 4.28+/-1.4%. Normative data in 24 monkeys, 3.0+/-0.7 years and 3.6+/-0.6 kg, revealed EI to be 16% higher in the right than left tibia (4.4+/-1.6 vs. 3.7+/-1.6 Nm2, P 〈 0.05). Five monkeys, restrained in chairs for 14 days, showed decreases in EI. There were no changes in EI in two chaired monkeys that lost weight during a 2-week space flight. The factors that account for both the decreases in bone mechanical properties after chair restraint at 1 g and lack of change after microgravity remain to be identified. Metabolic factors associated with body weight changes are suggested by our results.
    Keywords: Aerospace Medicine
    Type: Journal of medical primatology (ISSN 0047-2565); Volume 30; 6; 313-21
    Format: text
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  • 8
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    Influence of recreational activity and muscle strength on ulnar bending stiffness in men (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Bone bending stiffness (modulus of elasticity [E] x moment of inertia [I]), a measure of bone strength, is related to its mineral content (BMC) and geometry and may be influenced by exercise. We evaluated the relationship of habitual recreational exercise and muscle strength to ulnar EI, width, and BMC in 51 healthy men, 28-61 yr of age. BMC and width were measured by single photon absorptiometry and EI by mechanical resistance tissue analysis. Maximum biceps strength was determined dynamically (1-RM) and grip strength isometrically. Subjects were classified as sedentary (S) (N = 13), moderately (M) (N = 18), or highly active (H) (N = 20) and exercised 0.2 +/- 0.2; 2.2 +/- 1.3; and 6.8 +/- 2.3 h.wk-1 (P 〈 0.001). H had greater biceps (P 〈 0.0005) and grip strength (P 〈 0.05), ulnar BMC (P 〈 0.05), and ulnar EI (P = 0.01) than M or S, who were similar. Amount of activity correlated with grip and biceps strength (r = 0.47 and 0.49; P 〈 0.001), but not with bone measurements, whereas muscle strength correlated with both EI and BMC (r = 0.40-0.52, P 〈 0.005). EI also correlated significantly with both BMC and ulnar width (P 〈 0.0001). Ulnar width and biceps strength were the only independent predictors of EI (r2 = 0.67, P 〈 0.0001). We conclude that levels of physical activity sufficient to increase arm strength influence ulnar bending stiffness.
    Keywords: Aerospace Medicine
    Type: Medicine and science in sports and exercise (ISSN 0195-9131); Volume 25; 5; 592-6
    Format: text
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  • 9
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    In vivo assessment of forearm bone mass and ulnar bending stiffness in healthy men (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The cross-sectional bending stiffness EI of the ulna was measured in vivo by mechanical resistance tissue analysis (MRTA) in 90 men aged 19-89 years. MRTA measures the impedance response of low-frequency vibrations to determine EI, which is a reflection of elastic modulus E and moment of inertia I for the whole ulna. EI was compared to conventional estimates of bone mineral content (BMC), bone width (BW), and BMC/BW, which were all measured by single-photon absorptiometry. Results obtained from the nondominant ulna indicate that BW increases (r = 0.27, p = 0.01) and ulnar BMC/BW decreases (r = -0.31, p 〈 or = 0.005) with age. Neither BMC nor EI declined with age. The single best predictor of EI was BW (r2 = 0.47, p = 0.0001), and further small but significant contributions were made by BMC (r2 = 0.53, p = 0.0001) and grip strength (r2 = 0.55, p = 0.0001). These results suggest that the resistance of older men to forearm fracture is related to age-associated changes in the moment of inertia achieved by redistributing bone mineral farther from the bending axis. We conclude that the in vivo assessment of bone geometry offers important insights to the comprehensive evaluation of bone strength.
    Keywords: Aerospace Medicine
    Type: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (ISSN 0884-0431); Volume 7; 11; 1345-50
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  • 10
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    Tibial changes in experimental disuse osteoporosis in the monkey (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The mechanical properties and structural changes in the monkey tibia with disuse osteoporosis and during subsequent recovery are investigated. Bone mending stiffness is evaluated in relation to microscopic changes in cortical bone and Norland bone mineral analysis. Restraint in the semireclined position is found to produce regional losses of bone most obviously in the anterior-proximal tibiae. After six months of restraint, the greatest losses of bone mineral in the proximal tibiae range from 23 percent to 31 percent; the largest changes in bone stiffness range from 36 percent to 40 percent. Approximately eight and one-half months of recovery are required to restore the normal bending properties. Even after 15 months of recovery, however, the bone mineral content does not necessarily return to normal levels. Histologically, resorption cavities in cortical bone are seen within one month of restraint; by two and one-half months of restraint there are large resorption cavities subperiosteally, endosteally, and intracortically. After 15 months of recovery, the cortex consists mainly of first-generation haversian systems. After 40 months, the cortex appears normal, with numerous secondary and tertiary generations of haversian systems.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Calcified Tissue International (ISSN 0008-0594); 35; 1983
    Format: text
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