Degrees Of Internal Rotation Research Articles

Influence of the hip joint position on the intraosseous pressures in the juxta-articular bones. An experimental investigation in dogs.

In 6 mongrel dogs (eleven hips) the intraosseous pressure was measured in the femoral head as well as acetabulum in various hip joint positions. The control position for the measurements was 90 degrees flexion in which the pressures were found low and stable. The intraosseous pressure in both locations were subjected to consistent pronounced variations when the joint position was altered. In the femoral head, significant pressure increases (p less than or equal to 0.01) were found in maximal extension, maximal flexion, maximal adduction, 90 degrees external rotation, 45 degrees internal rotation, and maximal internal rotation. The pressure in acetabulum rose significantly in maximum flexion, 45 degrees internal rotation, and maximum internal rotation, whereas the pressure increase in maximal extension and maximum adduction was consistent but not significant. The pressure increase is most probably caused by inhibition of the venous drainage changing the bone hemodynamics in the juxta-articular bones. A complete obstruction of venous drainage was not observed since the intraosseous pressure in none of the measurements reached the level of the arterial pressure.

Rotational Brownian motion in a fluid with internal degrees of freedom

The coefficient of frictional torque acting on a rough hard sphere (Brownian particle) which rotates about a fixed axis in a fluid composed of finite-sized particles with internal rotational degrees of freedom is computed. Inertial effects are included. The long-time limit of the angular-velocity-autocorrelation function is obtained. We find that angular-velocity-autocorrelation function decays as ${t}^{\frac{\ensuremath{-}5}{2}}$, but with a coefficient that is altered from the usual Navier-Stokes result to include contributions from transport processes involving internal rotational degrees of freedom of the fluid.

Translational Brownian motion in a fluid with internal degrees of freedom

The friction coefficient for a smooth hard sphere (Brownian particle) moving through a fluid composed of finite-sized particles with internal rotational degrees of freedom is computed. Inertial effects are included. The long-time limit of the velocity-autocorrelation function is obtained. We find that the velocity-autocorrelation function decays as ${t}^{\ensuremath{-}\frac{3}{2}}$ but with a coefficient that is altered from the usual Navier-Stokes results to include contributions from transport processes involving internal rotational degrees of freedom of the fluid.

On the theory of homogeneous turbulence in fluid with internal rotations

The statistical description of homogeneous turbulence in incompressible fluid with internal angular momentum is made in the terms of both phenomenological and functional approaches. It is shown that in some region of scales the spectral characteristics of turbulence possess the universal behavior. In this region we made calculations of the kinetic and complete energy spectra, the spectrum of internal rotational momentum and the spectra of two-points cumulants of arbitrary degree. The main result is that the spectrum of kinetic energy in a fluid with internal rotations has the Kolmogorov's form “k−5/3”. Some features of homogeneous turbulence in a fluid with internal rotational degrees of freedom are discussed.

Biomechanics of the Shoulder

Man's shoulder girdle is of the general pattern of his tree-swinging ancestors. With assumption of the upright posture, man's thorax has flattened from anterior-posterior. This results in a rotation of the scapula to a position of 45 degrees with the sagittal plane. In addition to this, man's forearm is habitually used in a position of approximately 45 degrees of internal rotation. This places the biceps tendon "off its trolley" and leads to biceps tinosynovitis. Motions of the glenohumeral joints result from the force couple of the deltoid muscle plus the rotator cuff muscles. The rotator cuff alone can abduct the arm with 50% force throughout the full range of its motion. In the absence of the supraspinatus muscle, however, the force couple is disrupted. Although initiation of abduction is with full force, the force rapidly falls off to 90 degrees. Above 90 degrees the arm can barely support its own weight. Although the shoulder undergoes progressive degenerative changes with age, the necessity for a joint implant, either partial or total--although successful--is rare.

The lateral ankle sprain: an experimental study.

An experimental study in 39 ankles of the mechanisms of lateral ankle sprains was carried out using a simple qualitative apparatus. The mechanisms studied were: 1) supination-inversion, which was divided into ankle in plantar flexion and ankle in neutral position, since the orientation and tension of the ankle capsule and ligaments are related to the ankle position; 2) supination-internal rotation; and 3) supination-plantar flexion. Fresh amputation specimens were used. It was concluded that complete rupture of the anterior fibulotalar ligament is always the first lesion to occur in the lateral ankle sprain except when a supination force is applied to the ankle in neutral position when an incomplete tear of the fibulocalcaneal ligament may precede the total rupture of the anterior fibulotalar ligament. A partial rupture of the anterior deep fibers of the deltoid ligament can occur in extreme degrees of internal rotation or plantar flexion. A four-part grading system is suggested.

Aliphatic groups of sperm whale myoglobin: 13C NMR study.

The aliphatic region of the 13C NMR spectrum of sperm whale cyanoferrimyoglobin has been examined at 67.9 MHz. Fifty partially resolved or well-resolved resonances, representing at least half of the aliphatic carbons in the molecule, are observed in the spectral region from 9 to 29 ppm downfield of tetramethylsilane. Analyses of the spin lattice relaxation times (T1) and nuclear Overhauser enhancements for these resonances reveal considerable motion freedom of the aliphatic side chains. In the spectral region from 9 to 15 ppm, eight single carbon resonances are observed and tentatively assigned to Cdelta 1 of eight of the nine isoleucine residues. In at least five cases the reorientational motion of the isoleucine side chains could not be characterized solely by rotation of the Cdelta 1 methyl groups. The simplest model consistent with the data is a restricted diffusion model with two degrees of internal rotation [Wittenbort, R. J. & Szabo, A. (1978) J. Chem. Phys. 69, 1722--1736]. In light of the packing densities within the myoglobin molecule these results are taken to imply concerted motions of the buried aliphatic residues.

Arthrodesis of the Shoulder

Shoulder arthrodesis through the posterior approach in 6 patients with the average follow-up of 20 months has been described. There were no surgical complications. In all cases the position of the arm was determined clinically and placed in 20 degrees abduction, 30 degrees forward flexion, and 40 degrees internal rotation.

Simple model for second virial coefficients which includes angular coordinates. Calculation of second virial coefficients for hydrocarbons and their mixtures

A simple square well potential model for calculating the second virial coefficients of hydrocarbons is presented. The model includes, in a rough way, both internal and external angular coordinates, thus accounting for the major steric and entropic effects of molecules which are not spherically symmetric and which have internal rotational degrees of freedom. Methane, ethane and neopentane were used to establish the potential parameters. The second virial coefficients of eleven other hydrocarbons and hydrocarbon mixtures were calculated from these parameters. Calculated values differed from the experimental values by an average of 13 %. Adjusting the parameters for a good fit of all of the data gave deviations of < 10 % except for pentane which was high by 25 %.

Conformational Equilibria In α-Diazoketones by the Infrared Spectroscopy

Abstract It is well known that rotational isomers would appear as distinct species in the infrared spectrum only if there is a definite barrier to the freedom degree of internal rotation. In these conditions, it is possible to value the thermodynamic parameters related to the confornational equilibrium by means of the measure of the integrated absorption of infrared peaks deriving from the various conformers. α-Diazoketones are suitable compounds for this kind of investigations, since the possibility of conformational equilibria of type (I) has been established by different theoretical and experimental techniques.1–8

Free radical polymerization of unconjugated dienes XII. Temperature dependence of the cyclopolymerization of divinylether

AbstractThe temperature dependence of the extent of cyclization in the free radical polymerization of divinylether has been investigated. The tendency to further cyclization is greater for the six membered monocyclic radicals than for the five membered monocyclic radicals. The activation energies for the cyclization of both of these radicals are slightly greater than those for their addition onto monomer molecules. On the other hand, the activation entropies decidedly favour cyclization, suggesting that a loss of internal rotation degrees of freedom is less effective in decreasing entropy than a loss of translational and rotational degrees of freedom. This conclusion might represent a thermodynamic explanation of the reason why, in cyclopolymerization, intramolecular cyclization is so often favoured over intermolecular addition.

Continuum theory of thermotropic systems. Hydrodynamics of liquid crystals

The hydrodynamical parameters, i.e., the long-wave length and low-frequency properties of any homogeneous system are completely determined by the conservation laws and the static properties of the system, as described by various “elastic constants”. In this paper we present a unified formulation of hydrodynamics equally suitable for normal liquids, liquid crystals and solids, and apply it in detail to the nematic phase. The generality of this approach is of particular importance for the description of the dynamics near phase transitions. As variables we use quantities which have a meaning in any phase, namely, the densities of conserved quantities (particle number, momentum, angular momentum, and energy) and the entropy density, together with the corresponding current densities. In a continuum theory the various phases are characterized by their symmetry and by the static stresses, that they can sustain.The hydrodynamic equations including dissipation are then derived making use only of the familiar local conservation laws and general thermodynamic relations. We thus avoid introduction of hydrodynamic variables related to order parameters which are specific to particular phases. Consequently, we do not need any new conservation laws. This is accomplished by utilizing the conservation of angular momentum which is no longer a consequence of the conservation of linear momentum, if the particles have internal (rotational) degrees of freedom, as is essential for liquid crystals. We discuss for the nematic phase how the number of elastic and dissipative constants is reduced by restricting the most general set of equations by means of approximations which have been made in previous theories.Response functions and fluctuations of hydrodynamic variables are calculated in the hydrodynamic regime, particularly for the nematic phase. The hydrodynamic modes are discussed in detail for nematic liquid crystals. Apart from the compressional waves, one also gets the modes describing mainly the motion of the molecular axes. They are of diffusion type, as has been discussed previously. The coupling of compressional and orientational modes yields a characteristic anisotropy of sound attenuation and would thus supplement the experiments on orientational modes.

The gas-phase infrared spectra of nitromethane and methyl boron difluoride; fine structure caused by internal rotation

The gas-phase infrared spectra of nitromethane and methyl boron difluoride have been analysed in some detail. The various skeletal modes of vibration, and the vibrations of the methyl group with dipole changes parallel to the carbon–nitrogen and carbon–boron axes respectively, have vibration–rotation band contours which are of the expected type as calculated from the moments of inertia for overall rotation of the molecules. The perpendicular vibrations of the methyl groups all have complex contours, and in a number of cases widely-spaced fine structure lines are present. These can only be accounted for in terms of the internal rotation degrees of freedom. This is as expected because in classical terms the internal rotation frequencies modulate the oscillating vibrational dipole moment of these (and only these) methyl vibrations; in quantum-mechanical terms this leads to addi­tional transitions involving changes in the quantum number for internal rotation. These perpendicular methyl vibration bands have complex rotational structure because of interaction of the internal rotation degree of freedom with the overall rotations of these asymmetric top molecules. Nevertheless their main Q -branch features have been rather successfully analysed in terms of a theoretical model in which it is assumed that the internal rotation is free, and that the degeneracies of these perpendicular modes are retained. The former is expected to be a good approximation because of the known very low barriers to internal rotation. Some unresolved complexities, particularly towards the centres of the bands, may be caused by deviations from these simplifying assumptions. Analyses of the bands in this manner leads to information about the band origins and to reasonable values for the Coriolis coupling constants of the degenerate vibrations.

Abduction Cast in the Treatment of Perthes Disease

The purpose of treatment in Legg-Calvé-Perthes disease is the reduction of the deformity of the capital femoral epiphysis. For this aim, the lower limbs are enclosed from the groins to the toes in a plaster cylinder, and abduction sufficient to introduce the entire epiphysis within the acetabulum and some degree of internal rotation are provided by a wooden bar between the legs. Children in the abduction cast have unrestricted use of the flexion-extension range of hip motion. Weight-bearing is forbidden, but surprising range of activities are rapidly developed and enjoyed. The cases, which were treated in abduction cast for 12 months or more were studied using the measurement technique of Heyman and Herndon.The result are as follows:1. For the cases with sclerosing, flattening and fragmentation, abduction cast was effective, if femoral epiphysis was entirely put within acetabulum.2. For the cases in which healing process had already begun, abduction cast was not effective.3. For the deformity of the femoral neck, not effective.

METHOD FOR CALCULATION INTERNAL ROTATION BARRIERS.

A method is proposed for calculating internal rotation barriers in ethanelike molecules based on two effects, exchange interactions of the electrons in bonds adjacent to the bond about which internal rotation occurs and nonbonded or van der Waals interactions. A modified Buckingham or ``6-exp'' potential is used for the nonbonded interactions and a semiempirical method is used to obtain the constants in the 6-exp potential for the various kinds of nonbonded interactions. The equation for U(ω) contains one adjustable parameter, U0, which theoretically should be constant for all molecules within certain classes. An average value for U0 is obtained for each class from selected microwave values of ΔU by letting ΔU have the microwave experimental value and solving for U0. It was found that U0 was essentially constant within each class, thus allowing these average values to be used to calculate ΔU for all molecules in each class. Satisfactory agreement between the calculated values and experimental values of ΔU was obtained in all cases tested except two. A discussion is included of the extension of this method to more complex molecules with more than one internal rotational degree of freedom, allowing for other energy contributions such as distortion of bond angles. Brief mention is also made of the possible extension of the method to the conformational analysis of macromolecules such as polypeptides and synthetic polymers.

Elementary Rates of Decomposition of the Homologous Series Ethyl through 2-Octyl Radicals

The rates of decomposition of the secondary alkyl radicals 2-butyl, 2-pentyl, 2-hexyl, 2-heptyl, and 2-octyl were measured by an internal comparison method at 300°K. Activation to a level around 45 kcal mole−1 was by addition of H atom to the appropriate α-olefin. The validity of an assumption of invariance of thermochemical parameters, including the bond-dissociation energy D[3(—C)—(4—C)] for the higher members of the radical series, was established by measurements made with 5-Me-2-hexyl radicals. No evidence was found for any significant amount of H migration and isomerization of any of these excited radicals. Together with earlier work, measurements now exist for the homologous series ethyl through 2-octyl radicals. Theoretical rate constants agree well with the experimental values. Our earlier experimental verification for relatively smaller molecules that all vibrational and internal rotational degrees of freedom must be treated as active is now extended to the largest member of this series. Within the accuracy of the test provided by this work, intramolecular energy relaxation is also confirmed to be effectively random even for the highest member. The data illustrate the effect on rates of quantum-statistical weight changes due to structural increments in the series.

Collisional Transition Probabilities for Deactivation of Highly Vibrationally Excited Cyclopropane and Dimethylcyclopropane

Collisional deactivation of vibrationally excited cyclopropane and dimethylcyclopropane molecules, in their ground electronic states, has been studied with ethylene and cis-butene as the respective deactivators. Activation is to an energy region just above 100 kcal mole—1, which is reached by chemical activation. The activated molecules may isomerize, and the measurable cascade is to a reaction threshold at 60–65 kcal; below the threshold the excited molecules are stable with respect to reaction. The principle and characteristics of this steady-state method has been described in detail in Ref. 5. The two substrate molecules offer an interesting difference in internal rotational degrees of freedom. Cyclopropane was investigated at 298°, 598°, and 723°K, and dimethylcyclopropane at 573° and 673°K. The observed behavior was compared with model calculations for various assumed functional forms of collisional transition probabilities pij which include stepladder, Gaussian, and skewed distributions. The data, unfortunately, are too inaccurate to distinguish between these models clearly; but they do show that ethylene removes energy from cyclopropane in average steps which are at least 7 kcal (and in one system, perhaps, as high as 30 kcal); butene removes energy from dimethylcyclopropane in steps of at least 10–14 kcal; there is an indication that a step or Gaussian distribution fits the data better than a skewed exponential model. There is some evidence that the average step size decreases with increase of ambient temperature.

Dislocations of the Shoulder with Special Reference to Accompanying Small Fractures

1. A defect in the posterosuperior area of the anatomical neck of the humerus was demonstrated roentgenographically in patients with acute anterior dislocation and both by roentgenograms and at surgery in patients with recurrent anterior dislocations. 2. This defect can rarely be seen on conventional, routine roentgenograms of the shoulder; at times it can be demonstrated in an uncertain degree of internal rotation. It can easily be seen in the simple roentgenographic projection described. 3. Since this defect, if large, may facilitate recurrent dislocation, it should be looked for in all acute injuries. If it can be accomplished by adequate immobilization, this defect should be allowed to meal and fill in. 4. In recurrent dislocation of the shoulder the defect should be evaluated when planning surgical repair. It is the author's opinion that the defect, if large, should be repaired just as the labral defect is repaired anteriorly. 5. The defect, usually traumatic in origin, should not be confused with normal anatomical variations.

The Moments of Inertia of Molecules with Internal Rotation

The moments of inertia of some typical molecules with one internal rotational degree of freedom are obtained for all possible configurations; also the directions of the axes of least and greatest inertia. The dependence on the values of the structural parameters is discussed and illustrated.

RECURRENT DISLOCATION OF THE SHOULDER

A review of the pathology, mechanism, and operative treatment of recurrent dislocation of the shoulder, based on an analysis of 180 cases, with 159 operations, is presented. From this analysis the following conclusions have been made and appear to be substantiated: 1. The pathology comprises two important elements: (a) anterior detachment of the glenoid labrum from the bone margin of the glenoid, associated with some degree of stripping of the anterior part of the capsule from the front of the neck of the scapula, found in 87 per cent. of cases examined adequately at operation; (b) defect or flattening of the posterolateral aspect of the articular surface of the head of the humerus which engages with the glenoid cavity when the arm is in external rotation and abduction; this defect is demonstrated most readily in antero-posterior radiographs taken with the humerus in 60 to 70 degrees of internal rotation and was shown to be present in 82 per cent. of cases which had been subjected to adequate radiographic examination. 2. The frequency of the humeral head defect has been under-estimated in the past, because of the difficulty of demonstrating it, particularly when the defect is small. 3. Either type of lesion alone may predispose to recurrence of the dislocation. 4. Both types of lesion are often present in the same shoulder. When this is the case the tendency to redislocation is great. 5. The initial dislocation, which results in the development of one or both these persistent structural abnormalities, may be due to very different types of injury, the commonest of which is a fall on the outstretched hand. The factor common to all these injuries is a resultant force acting on the humeral head in the direction of the anterior glenoid margin. 6. In the treatment of recurrent dislocation of the shoulder joint the Nicola operation is unreliable, and it may be associated with a recurrence rate as high as 36 per cent. It is believed that continued instability after this operation is usually due to the presence of a defect of the humeral head. 7. Operative treatment should aim at repairing, or nullifying, the effects of both types of lesion. For anterior detachment of the labrum this involves either suturing the labrum back to the glenoid margin, or constructing some form of anterior buttress, fibrous or bony: for humeral head defects it necessitates some procedure designed to limit external rotation, thus preventing the defect from coming into engagement with the glenoid cavity. Such limitation of external rotation does not constitute a significant disability.