We have studied the stiffness of myofilament lattice in sarcomeres in the pre-force generating state, which was realized by a relaxing reagent, BDM (butane dione monoxime). First, the radial stiffness for the overlap regions of sarcomeres of isolated single myofibrils was estimated from the resulting decreases in diameter by osmotic pressure applied with the addition of Dextran. Then, the radia...

Elastic distortion of a structural element of the actomyosin complex is fundamental to the ability of myosin to generate motile forces. An elastic element allows strain to develop within the actomyosin complex (cross-bridge) before movement. Relief of this strain then drives filament sliding, or more generally, movement of a cargo. Even with the known crystal structure of the myosin head, howev...

After myocardial infarction, a poorly contracting nonischemic border zone forms adjacent to the infarct. The cause of border zone dysfunction is unclear. The goal of this study was to determine the myofilament mechanisms involved in postinfarction border zone dysfunction. Two weeks after anteroapical infarction of sheep hearts, we studied in vitro isometric and isotonic contractions of demembra...

We tested the hypotheses that Ca(2+) concentration ([Ca(2+)]) and sarcomere length (SL) modulate force development via graded effects on cross-bridge kinetics in chemically permeabilized rat cardiac trabeculae. Using sinusoidal length perturbations, we derived the transfer functions of stiffness over a range of [Ca(2+)] at a constant SL of 2.1 micrometer (n = 8) and at SL of 2.0, 2.1, and 2.2 m...

This paper presents a method for modeling and analysis of cablestayed bridges under the action of moving vehicles. Accurate and efficient finite elements are used for modeling the bridge structure. A beam element is adopted for modeling the girder and the pylons. Whereas, a two-node catenary cable element derived using exact analytical expressions for the elastic catenary, is adopted for modeli...

The dynamic behavior of railway bridges carrying high-speed trains can be analyzed with or without the consideration of the vehicle's own structure. However, due to the amount of kinetic energy carried at high speeds, the train may interact significantly with the bridge, especially when resonance occurs. Equally important is the riding comfort and the stability of the track and train cars, whic...

In order to relieve traffic congestion, irregularly-shaped bridges have been widely used in urban overpasses. However, the analysis on modal characteristics of irregularly-shaped bridges is not exhaustive, and the effect of design parameters on modal characteristics will be deeply investigated in future studies. In this paper, a novel strategy based on a free-interface mode synthesis algorithm ...

BACKGROUND The purpose of this study was to compare the biomechanical properties of locked versus nonlocked lateral fibular bridge plating of comminuted, unstable ankle fractures in a mode of catastrophic failure. METHODS We created comminuted Weber C fractures in 8 paired limbs from fresh cadavers. Fractures were plated with either standard or locked one-third tubular bridge plating techniqu...

This article presents a numerical study that aims to explore the dynamic behavior of railway bridges under vibrations induced by heavy-haul traffic. For this purpose, finite element code can conduct moving load and mass analysis single span was developed. The software validated comparing response analytical solution for various speeds. benchmark bridge train showed interplay between natural fre...