Body Torsion Research Articles

Cytoskeleton of Toxoplasma gondii.

The cytoskeleton of Toxoplasma gondii was studied by electron microscopy using whole mounts of detergent-extracted parasites and thin sections of routine preparations, tannic acid-stained organisms, and detergent-extracted parasites. In whole mounts, the spiral arrangement of the 22 pellicular microtubules closely corresponded to the pattern of surface ridges seen previously by scanning electron microscopy and reflected the torsion of the parasite body during locomotion. The microtubules had free posterior ends and were anchored anteriorly in the polar ring, presumed to be a microtubule organizing center (MTOC). The insertions of the microtubules were supported by blunt projections of the polar ring, forming a cogwheel pattern in transverse view. The internal microtubules had 13 protofilaments and were twice the length of the conoid. They extended through the conoid and ended at the anterior preconoidal ring, presumably a second MTOC. The subunits of the conoid were arranged in a counterclockwise spiral when traced from base to tip, as were the pellicular microtubules. We postulate that as the conoid moves, the polar ring complex moves along the spiral pathway of the conoid subunits. Retraction of the conoid would then rotate the polar ring, producing the torsion of the body we observed by SEM.

Torsion of elastic bodies bounded by coordinate surfaces of toroidal and spherical coordinate systems

On the basis of relationships between particular solutions of the torsion equation in toroidal and spherical coordinates, the Fourier method is applied to the solution of torsion contact problems for elastic bodies bounded by coordinate surfaces of toroidal and spherical coordinate systems.

Impulsive torsion of semi-infinite body with circular rod. (Analysis of generalized dynamic stress intensity factor)

To discuss the initiation of crack in the material, it will be important to get the knowledge about the singular stress at the bottom of the sharp notch. In this paper, dynamic singular stress field is discussed on the periphery of the periphery of the function part of the semi-infinite rod fixed on the surface of the semi-infinite body. It is assumed that the one dimensional torsional stress wave travels down the rod and arrived at the junction. Stresses on the rod and the semi-infinite body are analyzed based on the dynamic theory of elasticity and Laplace transformation method. An integral equation is solved numerically in the transformed domain. Stresses near the function and the generalized stress intensity factor are calculated from the above results by using the numerical inversion of the Laplace transformation.

Vibration Modes of a 70-Ton Boxcar

Vibration tests were performed on a 70-t boxcar both empty and fully loaded, with two packaging configurations. Nine vibration modes were identified: first roll, second roll, yaw, bounce, pitch, body torsion, body bending, and two lading modes. The effect of friction snubbing, gross weight, and amplitude of motion input at the rails was determined. Test results presented are a summary of modal frequencies, the deflections associated with each mode and the range of frequency variation.

Functional aspects of the integument in polypterid fishes

The integument and the axial musculoskeletal system of fishes belonging to the family Polypteridae (Osteichthyes, Actinopterygii) are re-examined with the purpose of clarifying the mechanical functions of the squamation. The major integumentary axes of bone and collagen are laid down in such a pattern as to resist that deformation of the skin resulting from axial body torsion. This resistance will have the effect of reducing or preventing such torsion and maintaining the strictly transverse plane of locomotory undulations.

Torsion of a spherical layer by a spherical annular stamp

Methods of reducing dual series equations to infinite algebraic systems /1,2/ are used to study a mixed problem of the theory of elasticity concerning the torsion of a spherical layer by a spherical annular stamp. The inner or outer surface of this layer is rigidly clamped, and the stamps are coupled to the other surface of the layer. The resulting infinite algebraic systems of first kind are reduced, after the regularization, to the systems of second kind, and the latter can be solved using the method of consecutive approximations. Authors of /3,4/ used the same method to study certain dynamic problems of torsion of bodies with spherical surfaces.

Elastoplatic torsion of bodies with rotational symmetry

Elastoplatic torsion of bodies with rotational symmetry

Solution of axisymmetric torsion problems by point matching

A general numerical technique is presented for the solution of the problem of torsion of axisymmetric bodies. The method superimposes a number of basic solutions of the elasticity equations using the point-matching technique so as to satisfy approximately the prescribed boundary conditions of a body. Results obtained by this technique are compared with those obtained by alternative experimental and theoretical techniques for various body geometries to assess the accuracy of the method. The technique is then applied to the problem of the torsion of shouldered shafts since large discrepancies exist between the experimental and analytical results available for this type of structure.

Die Augenstielbewegungen der Languste (Palinurus vulgaris)

Palinurus vulgaris shows clear compensatory eye stalk movements when turning actively around a vertical axis. Exactly the same eye stalk movements are observed after blinding of the animal (measurement of film pictures). On passive rotation only the intact animal shows compensatory eye stalk movements (= optomotoric reactions); in the blinded lobster such movements are lacking, except when a torsion of the body with respect to the legs is effectuated (stimulation of proprioceptors). It is suggested that the compensatory eye stalk movements of the actively turningPalinurus are no “optomotoric reactions”, and possibly no sensory reactions at all; but that they are spontaneous acts originating primarily within the central nervous system.

Torsion of Noncylindrical Shafts of Circular Cross Section

Abstract The theory of torsion of noncylindrical bodies of revolution, initiated by J. H. Michell and A. Föppl, is stated by a basic differential equation of the circumferential displacement and by a boundary condition of the shear stress along the generator surface. The solution of these two equations by the “direct” method of first assuming the boundary shape has not lent itself to closed solutions in terms of elementary functions, so that only approximation, infinite series, and experimental methods have been applied. A semi-inverse method analogous to Saint Venant’s semi-inverse method for cylindrical bodies has the disadvantage of the restriction to special boundary shapes but the advantage of exact solutions by means of elementary functions. By this method, bodies of conical, ellipsoidal, and hyperbolic boundary shapes have been obtained in a simple analysis. One class of integrals leading to other boundary shapes seems not to have been analyzed up to now, namely, the integrals in the form of a product of two functions of, respectively, axial (z) and radial (r) co-ordinates. A first suggestion of this possibility was given in Love’s treatise on the mathematical theory of elasticity. In the present paper, the classes of boundary shapes, displacements, and stress distributions are investigated analytically and numerically. The extent of the numerical investigation contains only the results of single-term integrals for full and hollow cross sections of technical interest. The detailed analysis of the boundary shapes, following from series integrals, presents essential mathematical obstacles. Overcoming these difficulties might lead to a multitude of solutions of interesting boundary shapes, and stress and strain distribution.

Specimen of Torsion of the Body of the Uterus

Specimen of Torsion of the Body of the Uterus