ABSTRACT
Purpose: The purpose of this study was to develop a measure of type 1 diabetes mellitus (T1DM) knowledge that is aimed at youth and is based on contemporary management standards. Methods: An 88-item test was derived from the American Association of Diabetes Educators 7 Self-Care Behaviors. Results: A multidisciplinary team selected the best 49 items which were piloted in a sample of 119 youths (59 males, aged 12-18, having a mean ± standard deviation glycated haemoglobin (A1C) of 9.9%±1.80 (84.7±19.7 mmol/mol). A minimum absolute point-biserial correlation coefficient of 0.250 was used to choose 49 items from the original 88 questions. Categorical principal component analysis was then used to identify the best factor analytical model that consisted of five factors composed of 19 items. These five factors explained 57% of item variances. Factors were associated with the latent variables: advanced problem-solving, hypoglycaemia prevention and management, taking insulin/medication administration, daily management and healthy active living. Conclusion: A new T1D knowledge test for youth was refined from 88 to 49 questions based on expert opinion and empirical test construction. The instrument was then refined to 19 items based on exploratory factor analysis. Future goals are to validate this factor model with another cohort and confirm concurrent validity based on youth's glycated haemoglobin and adherence behaviours. Our new T1DM knowledge measure initially appears valid and promising as a new clinical and research tool.
ABSTRACT
Spatial steady-state Lamb wave propagation in an anisotropic composite plate excited by harmonic surface sources is modeled using a Green's matrix representation in a frequency-wavenumber domain. An approach based on a residue integration technique for two dimensional wavenumber integrals for the computation of displacements outside an excitation source is presented in this paper. In the far-field zone of the excitation source, the method of stationary phase is used, which gives an asymptotic expansion of the displacement vector as a sum of cylindrical waves. Near caustic directions, a far-field solution is computed in terms of Airy functions. The results obtained applying residue integration technique and asymptotic expansion are found to be coinciding with the results of the computation by using the adaptive quadratures. Moreover, these approaches agree well with experimental data. Then, the advantages and disadvantages of the various methods applied for modeling of Lamb wave propagation are discussed in this paper. Focussing and other properties of Lamb waves are studied using numerical examples.
ABSTRACT
This article presents a numerical study of dispersion characteristics of some symmetric and antisymmetric composites modelled as multilayered packets of layers with arbitrary anisotropy of each layer. The authors introduce a subsidiary boundary problem of three-dimensional elasticity theory for the system of partial differential equations describing the harmonic oscillations of the composite caused by a surface load. The problem reduces to a boundary problem for ordinary differential equations by employing the Fourier transform. An algorithm of constructing the Fourier transform of the Green's matrix of the given boundary problem is presented. The wave numbers of Lamb waves propagating in composites, their phase velocity surfaces and group wave surfaces are presented through the poles of the transform of the Green's matrix. The authors obtain the dispersion curves for different directions and frequencies and investigate the dispersion curves and surfaces of wave numbers, phase velocities and group wave surfaces for various composites. The numerical results are then compared with the results obtained by applying other methods.
ABSTRACT
A common problem in pediatric endocrinology is limited growth potential resulting from advancing skeletal maturation. We determined the efficacy of letrozole, an aromatase inhibitor, on delaying bone age advancement in adolescent males with limited growth potential. Twenty-four patients met the study inclusion criteria. Six patients treated with androgen were analyzed separately. Low-dose ACTH stimulation tests were performed to ascertain the effect of letrozole on adrenal gland function. In patients not on androgen, bone age progression decelerated from 1.51+/-0.57 (deltabone age/deltachronological age) before treatment to 0.68+/-0.66 on therapy (mean duration 12.4 months; p <0.0005). Predicted adult height standard deviation scores (SDS) increased from -1.41+/-0.54 to -0.64+/-0.65 on treatment (p <0.0005). Similar results were noted in androgen-treated patients. Approximately one-fourth of patients displayed subnormal responsiveness to ACTH. In summary: 1) letrozole decelerates skeletal maturation, resulting in significant increases in predicted adult height, and 2) letrozole causes mild adrenal suppression.
