Straight Stretches Research Articles

Possibility of shortening the lengths of straight stretches of flowmeters with converging devices

Requirements of the technical and standardization documents in regard to lengths of the straight stretches of pipes of flowmeters with converging devices are considered and analyzed. It is shown that certain positions and requirements are baseless and incorrect. Recommendations are made on shortening the lengths of the straight stretches.

A new model for the geometry of the binding of myosin crossbridges to muscle thin filaments

We have used the method of three-dimensional image reconstruction of electron micrographs to analyse the structure of thin filaments and pure F-actin filaments decorated with myosin subfragment-1. To help improve on the earlier work of Moore et al. (1970), we have obtained all our data using minimal electron dose procedures to reduce radiation damage. Modifications in the specimen preparation have enabled us to process straight stretches of filament twice as long as any used in the earlier work, resulting in a corresponding improvement in the signal-to-noise ratio and the resolution. The results show significant changes in the density distribution in the region near the axis of the structure. Compared with the earlier model, the reconstructions show the presence of extra density close to the axis of the particle. We present a case for identifying actin with the density in this region, rather than with the density at higher radius previously designated as actin. This new assignment for the position of actin within the decorated filament structure leads to a radical change in the geometry of the model for myosin subfragment-lactin interaction. Furthermore, by comparing the features that we identify as actin with the reconstructed images of undecorated thin filaments published by Wakabayashi et al. (1975), we conclude that the polarity that has previously been assumed for the thin filament is incorrect. When the thin filament polarity is reversed, the position that tropomyosin is believed to occupy in the active state coincides with a weakly resolved feature in our reconstructions of decorated thin filaments. These findings, involving a reversal of thin filament polarity combined with the change in the geometry of myosin subfragment-1-actin interaction, allow a revised steric blocking model to be constructed.

Pista de bobs Innsbruck - Austria

The new artificial bob sleigh ice track was constructed on the occasion of the XII Winter Olympics. It is 1330 m long and consists of: straight stretches, right and left turn curves, supporting zones and a circular element with a 267° opening angle. The average slope between the starting point and the goal is 18%. The section of the dike consists of a 1.45 m wide horizontal part and 0.55 m high flanges except in the curves where the flange extends into a circular security arch which serves as a retaining element. For the construction the track was subdivided into 4 m long sections, each one with its own foundation. On this foundation were placed the prefabricated supporting ribs which sustain steel laths, graders of the profile in each section. The cooling pipes were placed hanging down from the ribs by way of distance plates. The complex forms a rigid unit by means of Design Mix. The track is further completed by; he cabins at the starting point and the goal; the power plant for the technical installations; access roads to the starting points for the competing bob-sleighs; roads for transportation of equipment material.