Bracing patients with idiopathic scoliosis: Design of the Dutch randomized controlled treatment trial

Background. The effectiveness of bracing patients with IS has not yet been convincingly established due to a lack of RCTs. Some authors suggest that their results confirm that bracing is effective; others conclude that the effectiveness of bracing is doubtful or recommend a RCT. The aim of this study was to establish whether bracing patients with idiopathic scoliosis (IS) in an early stage will result in at least 5 degrees less mean progression of the curvature compared to the control group after two years of follow-up. Methods. A randomized controlled trial was designed. Eligible patients are girls and boys in the age group 8-15 years whose diagnosis of IS has been established by an orthopedic surgeon, who have not yet been treated by bracing or surgery, and for whom further growth of physical height is still expected based on medical examination and maturation characteristics (Risser ? 2). The Cobb angle of the eligible patient should either be minimally 22 and maximally 29 degrees with established progression of more than 5 degrees, or should be minimally 30 and maximally 35 degrees; established progression for the latter is not necessary. A total of 100 patients will be included in this trial. The intervention group will be treated with full-time Boston brace wear; the control group will not be braced. Every four months, each patient will have a physical and an X-ray examination. The main outcomes will be the Cobb angle two years after inclusion and health-related quality of life. Discussion. The results of this trial will be of great importance for the discussion on early treatment for scoliosis. Furthermore, the result will also be important for screening for scoliosis policies. Trial registration. Nederlands Trialregister ISRCTN36964733

Evolution of deformation and recrystallization textures in high-purity Ni and the Ni-5 at. pct W alloy

An attempt has been made to study the evolution of texture in high-purity Ni and Ni-5 at. pct W alloy prepared by the powder metallurgy route followed by heavy cold rolling (∼95 pct deformation) and recrystallization. The deformation textures of the two materials are of typical pure metal or Cu-type texture. Cube-oriented ({001} {100}) regions are present in the deformed state as long thin bands, elongated in the rolling direction (RD). These bands are characterized by a high orientation gradient inside, which is a result of the rotation of the cube-oriented cells around the RD toward the RD-rotated cube ({013} {100}). Low-temperature annealing produces a weak cube texture along with the {013} {100} component, with the latter being much stronger in high-purity Ni than in the Ni-W alloy. At higher temperatures, the cube texture is strengthened considerably in the Ni-W alloy; however, the cube volume fraction in high-purity Ni is significantly lower because of the retention of the {013} {100} component. The difference in the relative strengths of the cube, and the {013} {100} components in the two materials is evident from the beginning of recrystallization in which more {013} {100} -oriented grains than near cube grains form in high-purity Ni. The preferential nucleation of the near cube and the {013} {100} grains in these materials seems to be a result of the high orientation gradients associated with the cube bands that offer a favorable environment for early nucleation

Evolution of Microstructure and Texture during Warm Rolling Of a Duplex Steel

The effect of warm rolling on the evolution of microstructure and texture in a duplex stainless steel (DSS) was investigated. For this purpose, a DSS steel was warm rolled up to 90 pct reduction in thickness at 498 K, 698 K, and 898 K (225 °C, 425 °C, and 625 °C). The microstructure with an alternate arrangement of deformed ferrite and austenite bands was observed after warm rolling; however, the microstructure after 90 pct warm rolling at 498 K and 898 K (225 °C and 625 °C) was more lamellar and uniform as compared to the rather fragmented and inhomogeneous structure observed after 90 pct warm rolling at 698 K (425 °C). The texture of ferrite in warm-rolled DSS was characterized by the presence of the RD (〈011〉//RD) and ND (〈111〉//ND) fibers. However, the texture of ferrite in DSS warm rolled at 698 K (425 °C) was distinctly different having much higher fraction of the RD-fiber components than that of the ND-fiber components. The texture and microstructural differences in ferrite in DSS warm rolled at different temperatures could be explained by the interaction of carbon atoms with dislocations. In contrast, the austenite in DSS warm rolled at different temperatures consistently showed pure metal- or copper-type deformation texture which was attributed to the increase in stacking fault energy at the warm-rolling temperatures. It was concluded that the evolution of microstructure and texture of the two constituent phases in DSS was greatly affected by the temperature of warm rolling, but not significantly by the presence of the other phas

TEXTURE DEVELOPMENT AND TEXTURE INHOMOGENEITIES IN A HOT-ROLLED CuZnAl SHAPE MEMORY ALLOY

The texture development in a hot rolled Cu-14.2wt.%Zn-5.6wt.%Al in the surface and centre of the sheet was studied. The observed texture in the centre of the sheet can be understood in terms of the {001}(011) and {211}(011) hot rolling texture in the austenite phase and the reported crystallographic orientation relationships between monoclinic martensite and b.c.c. austenit. In the surface of the sheet the texture was developed with the influence of shear deformation. Therefore in the martensitic phase only the orientation components were observed which were originated from the {001}(011) of the b.c.c. phase. Besides the variant selection of the crystal orientation was observed during the pahse transformation in the surface of the sheet

Determination of the odd part of the texture function

By calculating the series expansion of the orientation distribution function (O.D.F.) from experimental pole-figures, previously only the even part (l even) could be considered, since the pole-figures are necessarily centro-symmetric. When the condition of non-negativity of the O.D.F. is taken into account, particularly in the null-domains in which the O.D.F. is zero, it is also possible to determine the odd part of the development by means of an approximation method. From individual orientation measurements, it is also possible to determine the even and odd parts of the O.D.F.Lors du calcul du développement en série de la fonction de distribution des orientations (F.D.O.) à partir de figures de pôles expérimentales, seule la partie paire (rangs l pair) a pu être considérée à ce jour, puisque les figures de pôles sont nécessairement centro-symétriques. Si l'on tient compte de la condition de non-négativité de la F.D.O., et ce plus particulièrement dans les domaines nuls dans lesquels la F.D.O. prend la valeur zéro, il est également possible de déterminer la partie impaire du développement par une méthode d'approximation. A partir de mesures d'orientations individuelles, il est également possible de déterminer les parties paires et impaires de la F.D.O

Description of the texture by distribution functions on the space of orthogonal transformations. Implications on the inversion centre

In the most general case the orientation distribution function (texture) is a function on the space of orthogonal transformations which splits into a couple of functions on the space of rotations. In the case of non-enantiomorphic crystal symmetry groups only one of these functions is independent. Sample symmetry (especially centrosymmetry) can be achieved in a trivial and a non-trivial way. The first one leads to relations between individual functional values the latter one to integral relations.Dans le cas le plus général, la fonction de distribution des orientations (texture) est une fonction sur l'espace des transformations orthogonales, qui se scinde en un couple de fonctions sur l'espace des rotations. Dans le cas de groupes de symétrie cristalline non énantiomorphes, une seule de ces fonctions est indépendante. La symétrie d'échantillon (notamment la centro-symétrie) peut être réalisée d'une façon triviale et d'une façon non-triviale. La première conduit à des relations entre des valeurs individuelles de fonction, la seconde à des relations intégrales

An inversion formula expressing the texture function in terms of angular distribution functions

The determination of the orientation distribution function of crystallites in a polycrystalline material from experimental pole figures leads to an integral equation which is usually solved by a series expansion method. Recently S. Matthies [4] has proposed, without proof, an inversion formula which is not based on series expansion. Such a direct formula is being deduced by efficient group theoretical methods. The solution can further be expressed in terms of the angular distribution function Why(cos θ) which had been introduced earlier [3]. Both methods are being compared with regard to the obtainable experimental data and the required computational efforts.La détermination de la fonction de distribution des orientations de cristallites dans un matériau polycristallin à partir de figures de pôles expérimentales conduit à une équation intégrale qui est généralement résolue par une méthode de développement en série. Récemment S. Matthies [4] a proposé, sans démonstration, une formule d'inversion qui n'est pas basée sur un développement en série. Une telle formule directe est déduite par des méthodes efficaces de théorie des groupes. La solution peut être ultérieurement exprimée au moyen de la fonction de distribution angulaire Why(cos θ) qui avait été introduite précédemment [3]. Les deux méthodes sont comparées pour ce qui conceme les données expérimentales accessibles et l'effort de calcul numérique requis