[The advantages of 3D imagery in diagnosing and supervising children's and teenagers' scoliosis]

Scoliosis is an abnormal curvature of the spine. One or several curves of more than 10 degrees in the frontal plane can be seen with the rotation of vertebrae in the axial plane, which modifies sagittal curves. In addition to esthetic harm, the morbidity of a scoliosis depends on the extent of the deformation. Treatment, whether it be orthopedic or surgical, is aggressive and never completely cures the condition. At best the deformation will be stabilized at the end of growth. Therefore, it is essential to detect any slight curve and quickly identify any potential progressive form in order to treat it. Visualization of scoliosis in 3D through spine modeling has several advantages at each stage of care. First, with slight curvatures, 3D modeling allows the medical staff to confirm the scoliosis by showing the modification in the three different planes. All curvatures will not progress. Orthopedic treatment is constraining and expensive; only progressive forms will receive it. When the curvature is slight and does not need immediate treatment, 3D modeling at each successive check-up will help detect any sign of likely progression quickly and reliably. Moreover, the medical observation of corset treatment and the preoperative work-up are improved because all 3D parameters of the deformation are accessible. The need for 3D modeling for scoliosis has been known for a long time, but no tool allowing a vertical study with a low level of radiation was available. The EOS imagery system meets these criteria through an optimal analysis of deformations caused by scoliosis.

Dispersive crystal field excitations and quadrupolar interactions in UPd3

We report inelastic neutron scattering measurements and random phase approximation calculations of the dispersive crystal field excitations of UPd(3). The measured spectra at lower energies agree with those calculated using quadrupolar interaction parameters deduced from bulk and x-ray scattering measurements. The more intense excitations arising from the hexagonal sites were used to obtain exchange parameters which proved to be anisotropic.

Morphology of the superconducting vortex lattice in ultrapure niobium

The morphology of the superconducting flux line lattice (FLL) of Nb comprises gradual variations with various lock-in transitions and symmetry breaking rotations. We report a comprehensive small-angle neutron scattering study of the FLL in an ultrapure single crystal of Nb as a function of the orientation of the applied magnetic field. We attribute the general morphology of the FLL and its orientation to three dominant mechanisms; first, nonlocal contributions, second, the transition between open and closed Fermi surface sheets and, third, the intermediate mixed state between the Meissner and the Shubnikov phase.

Dipolar excitations at the LIII x-ray absorption edges of the heavy rare-earth metals

We report measured dipolar asymmetry ratios at the LIII edges of the heavy rare-earth metals. The results are compared with a first-principles calculation and excellent agreement is found. A simple model of the scattering is developed, enabling us to reinterpret the resonant x-ray scattering in these materials and to identify the peaks in the asymmetry ratios with features in the spin and orbital moment densities.

Magnetoelastic nature of the dodecagonal anisotropy in holmium metal

We have investigated the magnetoelastic nature of the dodecagonal anisotropy in the magnetic anisotropy energy (MAE) in the basal plane of the hcp crystalline structure in holmium single crystal. We have proved that the origin of the second harmonic of the hexagonal symmetry in MAE clearly lies on a sixth-order magnetoelastic coupling term. The appearance of a 12-fold anisotropy in MAE in a single crystal having hexagonal symmetry provides a new insight on how the magnetic anisotropy can be modified in a magnetic material with giant spin-lattice coupling.

Determination of the antiferroquadrupolar order parameters in UPd(3)

By combining accurate heat capacity and x-ray resonant scattering results we have resolved the long standing question regarding the nature of the quadrupolar ordered phases in UPd(3). The order parameter of the highest temperature quadrupolar phase has been uniquely determined to be antiphase Q{zx} in contrast to the previous conjecture of Q{x{2}-y{2}}. The azimuthal dependence of the x-ray scattering intensity from the quadrupolar superlattice reflections indicates that the lower temperature phases are described by a superposition of order parameters. The heat capacity features associated with each of the phase transitions characterize their order, which imposes restrictions on the matrix elements of the quadrupolar operators.

Spontaneous symmetry-breaking vortex lattice transitions in pure niobium

We report an extensive investigation of magnetic vortex lattice (VL) structures in single crystals of pure niobium with the magnetic field applied parallel to a fourfold symmetry axis, so as to induce frustration between the cubic crystal symmetry and hexagonal VL coordination expected in an isotropic situation. We observe new VL structures and phase transitions; all the VL phases observed (including those with an exactly square unit cell) spontaneously break some crystal symmetry. One phase even has the lowest possible symmetry of a two-dimensional Bravais lattice. This is quite unlike the situation in high-Tc or borocarbide superconductors, where VL structures orient along particular directions of high crystal symmetry. The causes of this behavior are discussed.

Observation of a strongly nested Fermi surface in the shape-memory alloy Ni0.62Al0.38

The Fermi surface topology of the shape-memory alloy Ni0.62Al0.38 has been determined using Compton scattering. A large area of this Fermi surface can be made to nest with other areas by translation through a vector of approximately 0.18[1,1,0](2pi/a), which corresponds to the wave vector associated with martensitic precursor phenomena such as phonon softening and diffuse streaking in electron diffraction patterns. This observation is compelling evidence that these phenomena are driven by the enhanced electron-lattice coupling due to the Fermi surface nesting.

Intrinsic behavior of flux lines in pure niobium near the upper critical field

We report small-angle neutron-scattering (SANS) measurements of flux line properties near H(c2) in an ultrapure sample of niobium with weak pinning of flux in the bulk. These confirm in detail the Abrikosov picture of the flux line lattice to within 20 mK of the upper critical field line. However, it has recently been claimed [X. S. Ling et al., Phys. Rev. Lett. 86, 712 (2001)], on the basis of SANS observations of a disordering of flux lines in niobium, that the flux lattice melts at temperatures clearly separated from the upper critical field line. This discrepancy may possibly arise from differences in sample purity and pinning.

Strategies for assessing the implications of malformed frogs for environmental health

The recent increase in the incidence of deformities among natural frog populations has raised concern about the state of the environment and the possible impact of unidentified causative agents on the health of wildlife and human populations. An open workshop on Strategies for Assessing the Implications of Malformed Frogs for Environmental Health was convened on 4-5 December 1997 at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina. The purpose of the workshop was to share information among a multidisciplinary group with scientific interest and responsibility for human and environmental health at the federal and state level. Discussions highlighted possible causes and recent findings directly related to frog deformities and provided insight into problems and strategies applicable to continuing investigation in several areas. Possible causes of the deformities were evaluated in terms of diagnostics performed on field amphibians, biologic mechanisms that can lead to the types of malformations observed, and parallel laboratory and field studies. Hydrogeochemistry must be more integrated into environmental toxicology because of the pivotal role of the aquatic environment and the importance of fates and transport relative to any potential exposure. There is no indication of whether there may be a human health factor associated with the deformities. However, the possibility that causal agents may be waterborne indicates a need to identify the relevant factors and establish the relationship between environmental and human health in terms of hazard assessment.

Full-thickness Martius grafts to preserve vaginal depth as an adjunct in the repair of large obstetric fistulas

We performed a modified bulbocavernosus full-thickness pedicle graft procedure on four patients with large obstetric fistulas in Ghana, West Africa. The bulbocavernosus fat pad was harvested in the usual manner, and the full-thickness skin patch was taken from the medial thigh. All grafts showed 100% take by the tenth postoperative day. Adequate vaginal depth and caliber were obtained in all patients. Sexual function resumed in all patients except one, who suffered a recurrent vesicovaginal fistula. This method of vaginoplasty may be useful in patients who have massive vaginal-wall destruction of either gynecologic or obstetric origin.

Vesicovaginal fistula revisited

Vesicovaginal fistulas remain common and serious problems for women in West Africa. Thirty-six surgical repairs done during visiting professorships by American gynecologists between the years 1978-1987 are documented. The overall success rate was 70%. The management of large (greater than 4 cm) obstetric fistulas was especially difficult until the Latzko technique was abandoned for the technique of wide mobilization of vaginal flaps over the fistula site. This technique reduced the failure rate from 75% through 1986 to approximately 25% in 1987. Ongoing controversies and basic principles of surgical techniques in fistula repair are reviewed.