Calcium intake, physical activity and bone health status among Chinese early adolescents

The objective of this cross-sectional study was to determine the relationship between calcium intake and physical activity with bone health status among Chinese early adolescents. A selfadministered questionnaire was used to obtain socio-demographic background, family history of osteoporosis, lifestyle practices and eating habits; while daily calcium intake was assessed using one-day dietary recall and two-day dietary record. Physical activity was examined using PAQ-A (Physical Activity Questionnaire for Adolescents). Height, weight and bone health status was assessed using stadiometer, weighing scale (TANITA), and ultrasonometry QUS-2, respectively. Data was analysed using the Statistical Package for Social Sciences (SPSS), version 15.0. A total of 236 Chinese subjects were recruited into this study. The mean age of subjects was 13.6 ± 0.5 years old. Mean daily calcium intake was low, that is 573.4 ± 405.1mg. The mean score of PAQ-A was 2.14 ± 0.64. Mean weight, height, and BMI were 50.9 ± 11.4kg, 1.62 ± 0.08m and 19.40 ± 3.72kg/m2, respectively. Based on CDC classification of BMI-for-age (2000), 68.2% of subjects were in the normal category, 16.1% were underweight, 11.4% were at risk of overweight and 4.2% overweight. Mean Broadband Ultrasound Attenuation (BUA) was 77.55 ± 11.73dB/MHz. According to diagnostic criteria for osteoporosis by WHO (1994), 49.2% of subjects had normal bone mass (t-score > -1.0), more than half of the subjects were either osteopenic (49.6%) or osteopototic (1.3%). This might be due to subjects being in the early adolescents state and their peak bone mass has yet to be attained. T-test showed that there was significant difference between mean body weight among male and female subjects. There was also significant higher mean BUA among female subjects than their counterparts. Pearson correlation test showed that there was no significant relationship between BUA with calcium intake (r= -0.05, p= 0.42) or physical activity (r= 0.03, p= 0.69). However, weight had a significant positive correlation with BUA (r= 0.39, p<0.05). In conclusion, female subjects have better bone health status as compared to males. Although no significant relationship was shown between calcium intake and physical activity with bone health, these two factors are known to reduce future risk of osteoporosis. It is recommended that prevention and management of low bone mass should be focused on factors recognised as determinants of bone health status among early adolescents. This is to ensure optimal bone health being attained among the young population in reducing risk of osteoporosis in future

Shuttle STS-2 mission communication systems RF coverage and performance predictions. Volume 1: Ascent

The RF communications capabilities and nominally expected performance for the ascent phase of the second orbital flight of the shuttle are provided. Predicted performance is given mainly in the form of plots of signal strength versus elapsed mission time for the STDN (downlink) and shuttle orbiter (uplink) receivers for the S-band PM and FM, and UHF systems. Performance of the NAV and landing RF systems is treated for RTLS abort, since in this case the spacecraft will loop around and return to the launch site. NAV and landing RF systems include TACAN, MSBLS, and C-band altimeter. Signal strength plots were produced by a computer program which combines the spacecraft trajectory, antenna patterns, transmit and receive performance characteristics, and system mathematical models. When available, measured spacecraft parameters were used in the predictions; otherwise, specified values were used. Specified ground station parameter values were also used. Thresholds and other criteria on the graphs are explained

A Time-Accurate Upwind Unstructured Finite Volume Method for Compressible Flow with Cure of Pathological Behaviors

A time-accurate, upwind, finite volume method for computing compressible flows on unstructured grids is presented. The method is second order accurate in space and time and yields high resolution in the presence of discontinuities. For efficiency, the Roe approximate Riemann solver with an entropy correction is employed. In the basic Euler/Navier-Stokes scheme, many concepts of high order upwind schemes are adopted: the surface flux integrals are carefully treated, a Cauchy-Kowalewski time-stepping scheme is used in the time-marching stage, and a multidimensional limiter is applied in the reconstruction stage. However even with these up-to-date improvements, the basic upwind scheme is still plagued by the so-called "pathological behaviors," e.g., the carbuncle phenomenon, the expansion shock, etc. A solution to these limitations is presented which uses a very simple dissipation model while still preserving second order accuracy. This scheme is referred to as the enhanced time-accurate upwind (ETAU) scheme in this paper. The unstructured grid capability renders flexibility for use in complex geometry; and the present ETAU Euler/Navier-Stokes scheme is capable of handling a broad spectrum of flow regimes from high supersonic to subsonic at very low Mach number, appropriate for both CFD (computational fluid dynamics) and CAA (computational aeroacoustics). Numerous examples are included to demonstrate the robustness of the methods

Robust and Simple Non-Reflecting Boundary Conditions for the Euler Equations - A New Approach based on the Space-Time CE/SE Method

This paper reports on a significant advance in the area of nonreflecting boundary conditions (NRBCs) for unsteady flow computations. As a part of t he development of t he space-time conservation element and solution element (CE/SE) method, sets of NRBCs for 1D Euler problems are developed without using any characteristics- based techniques. These conditions are much simpler than those commonly reported in the literature, yet so robust that they are applicable to subsonic, transonic and supersonic flows even in the presence of discontinuities. In addition, the straightforward multidimensional extensions of the present 1D NRBCs have been shown numerically to be equally simple and robust. The paper details the theoretical underpinning of these NRBCs, and explains t heir unique robustness and accuracy in terms of t he conservation of space-time fluxes. Some numerical results for an extended Sod's shock-tube problem, illustrating the effectiveness of the present NRBCs are included, together with an associated simple Fortran computer program. As a preliminary to the present development, a review of the basic CE/SE schemes is also included

Vlasov Description Of Dense Quark Matter

We discuss properties of quark matter at finite baryon densities and zero temperature in a Vlasov approach. We use a screened interquark Richardson's potential consistent with the indications of Lattice QCD calculations. We analyze the choices of the quark masses and the parameters entering the potential which reproduce the binding energy (B.E.) of infinite nuclear matter. There is a transition from nuclear to quark matter at densities 5 times above normal nuclear matter density. The transition could be revealed from the determination of the position of the shifted meson masses in dense baryonic matter. A scaling form of the meson masses in dense matter is given.Comment: 15 pages 4 figure

Near-Field Noise Computation for a Subsonic Coannular Jet

A high-Reynolds-number, subsonic coannular jet is simulated, using a three-dimensional finite-volume LES method, with emphasis on the near field noise. The nozzle geometry used is the NASA Glenn 3BB baseline model. The numerical results are generally in good agreement with existing experimental findings

Semiconductor photocatalysis to engineering deuterated N-alkyl pharmaceuticals enabled by synergistic activation of water and alkanols

Precisely controlled deuterium labeling at specific sites of N-alkyl drugs is crucial in drug-development as over 50% of the top-selling drugs contain N-alkyl groups, in which it is very challenging to selectively replace protons with deuterium atoms. With the goal of achieving controllable isotope-labeling in N-alkylated amines, we herein rationally design photocatalytic water-splitting to furnish [H] or [D] and isotope alkanol-oxidation by photoexcited electron-hole pairs on a polymeric semiconductor. The controlled installation of N-CH3, -CDH2, -CD2H, -CD3, and -13CH3 groups into pharmaceutical amines thus has been demonstrated by tuning isotopic water and methanol. More than 50 examples with a wide range of functionalities are presented, demonstrating the universal applicability and mildness of this strategy. Gram-scale production has been realized, paving the way for the practical photosynthesis of pharmaceuticals