Unmarried mothers and their relationships with their dominating mothers.

Thesis (M.S.)--Boston Universit

The preparation and reactions of highly chlorinated indoles

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A study of the polymorphism of 4-methyl-2-nitroacetanilide and related compounds

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.The full crystal structures of three polymorphs of 4-methyl-2-nitroacetanilide (MNA) are described. The white form (MNA-l), is the most stable form. The least stable form is the amber farm (MNA-2). The yellow form (MNA-3) has been found to change in a topotactic manner into the white form. The relationships between the three polymorphs are discussed and possible mechanisms to account for the topotactic phase changes are presented. The polymorphs show different i.r. and Raman spectra in the solid state. These spectra, and those of deuterated analogues are interpreted and their differences explained. A study of the proton and 13-C n.m.r. spectra show that the conformation of flexible MNA molecules is markedly dependent on the nature of the solvent. The ability of other o-nitroacetanilides to exist in a white (intermolecular) and yellow (intramolecular hydrogen bonded) forms has been examined. Finally, details of the synthesis of these compounds and an account of the examination of MNA polymorphs by differential scanning calorimetry (d.s.c) are described. A description of computer programs used, including one in BASIC which will enable the contents of unit cell(s) to be viewed, is given.Berkshire Education Committe

APPLICATION OF SIMULATION TO FREESTYLE AERIAL SKIING

The aim of this study was to use a computer simulation model of aerial movement to investigate the ability of asymmetrical arm movements to initiate twist in the flight phase of a triple layout somersault in the aerials event of freestyle skiing. Three arm movements were analysed resulting in triple somersaults with four and five twists together with lead up movements with one twist less. It is concluded that four twists can be initiated during flight using two phases of asymmetrical arm movement and that the production of five twists requires three phases of asymmetrical arm movement

Are joint torque models limited by an assumption of monoarticularity?

This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Iso velocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex M J dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary

An isovelocity dynamometer method to determine monoarticular and biarticular muscle parameters

This study aimed to determine whether subject-specific individual muscle models for the ankle plantar flexors could be obtained from single joint isometric and isovelocity maximum torque measurements in combination with a model of plantar flexion. Maximum plantar flexion torque measurements were taken on one subject at six knee angles spanning full flexion to full extension. A planar three-segment (foot, shank and thigh), two muscle (soleus and gastrocnemius) model of plantar flexion was developed. Seven parameters per muscle were determined by minimizing a weighted root mean square difference (wRMSD) between the model output and the experimental torque data. Valid individual muscle models were obtained using experimental data from only two knee angles giving a wRMSD score of 16 N m, with values ranging from 11 to 17 N m for each of the six knee angles. The robustness of the methodology was confirmed through repeating the optimization with perturbed experimental torques (±20%) and segment lengths (±10%) resulting in wRMSD scores of between 13 and 20 N m. Hence, good representations of maximum torque can be achieved from subject-specific individual muscle models determined from single joint maximum torque measurements. The proposed methodology could be applied to muscle-driven models of human movement with the potential to improve their validity

Twisting techniques used in freestyle aerial skiing

At the 1988 Calgary Winter Olympics, six triple somersaults with three twists or four twists were filmed using two cameras. Angles describing body configuration and orientation were determined and were used as input into a computer simulation model of aerial movement. It was found that the twist angle of each simulation deviated from the corresponding angie obtained fTom film hy less than 0.08 revolutions during the first somersault of each movement. Contributions to the tilt angle after one somersault were determined using simulations based on modifications ofthe film data. It was found that of the six competitors, two initiated the twist during the takeoff phase, two initiated the twist during the aerial phase, and two used a combination of both methods

The biomechanics of twisting somersaults. Part III: aerial twist

A simulation model and a rigid body model are used to evaluate aerial twisting techniques. It is found that when somersault is not present, a number of cycles of segment counter-rotation are required to produce one twist. When somersault is present, twist may be introduced by producing tilt using asymmetrical movements of the arms, chest or hips about the sagittal plane. The same asymmetrical movements may be used to remove tilt, although the effectiveness of these techniques is dependent upon body configuration and the direction of somersault

The biomechanics of twisting somersaults. Part IV: partitioning performances using the tilt angle

A method is presented for determining the contributions made by contact and aerial twisting techniques in filmed performances of twisting somersaults. An 11-segment simulation model is used to determine the effects of removing asymmetries about the sagittal plane. Tilt contributions are determined for four competitive movements performed by an elite trampolinist. It is found that even in movements in which the twist is evident at takeoff, aerial techniques make a greater contribution than contact techniques

Twisting double somersault high bar dismounts

At the 1988 Seoul Olympic Games, four double somersault dismounts with one twist and four double somersault dismounts with two twists were filmed using two 16 mm cameras during the men's horizontal bar competitions. Contributions to tilt angle reached at the midtwist position, determined using computer simulations based on modifications of the data obtained from film, were used as measures of the twisting potential of various techniques. The amount of tilt produced was greater when total twist was greater and when the body was tucked rather than straight. The twisting techniques used varied with the timing of the twist within the two somersaults. Contact contributions were larger when there was more twist in the first somersault. When there was little or no twist in the first somersault, the major contribution came from aerial techniques that comprised mainly arm movements and asymmetrical hip movements in the flight phase