A suggested prototype for assessing bone health

Background- Osteoporosis is becoming a health concern worldwide. Considering the fact that prevention plays an important role in reducing the burden of this silent disease and in view of the limited resources available, many countries have adopted certain programs to fight osteoporosis through shifting their attention towards at-risk individuals. The Iranian Multicenter Osteoporosis Study (IMOS) is one of these programs. The program aims to assess bone health and the prevalence of vitamin D deficiency in different parts of Iran with various altitudes, latitudes and lifestyle habits in a way that the results could be generalized to the country. Method- The present article presents the protocol used in the third phase of the study. It was designed based on the experiences gathered in the previous phases to overcome the shortcomings particularly subject loss. The questionnaire applied in this study was developed based on a thorough literature review of the risk factors and secondary causes of osteoporosis and was approved by an expert panel. It should be added that while the majority of the existing studies aim to study a certain aspect of osteoporosis, the present protocol provides the information needed for policy makers and researchers to study different osteoporosis-related issues. Conclusion- The authors believe the protocol, to be implemented with small modifications, can help policymakers in different parts of the world, particularly developing countries, gather accurate information on different aspects of bone health at the national level. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved

First-principles calculation of intrinsic defect formation volumes in silicon

We present an extensive first-principles study of the pressure dependence of the formation enthalpies of all the know vacancy and self-interstitial configurations in silicon, in each charge state from -2 through +2. The neutral vacancy is found to have a formation volume that varies markedly with pressure, leading to a remarkably large negative value (-0.68 atomic volumes) for the zero-pressure formation volume of a Frenkel pair (V + I). The interaction of volume and charge was examined, leading to pressure--Fermi level stability diagrams of the defects. Finally, we quantify the anisotropic nature of the lattice relaxation around the neutral defects.Comment: 9 pages, 9 figure

The favoured cluster structures of model glass formers

We examine the favoured cluster structures for two new potentials, which both behave as monatomic model glass-formers in bulk. We find that the oscillations in the interatomic potential lead to global minima that are non-compact arrangements of linked 13-atom icosahedra. We find that the structural properties of the clusters correlate with the glass-forming propensities of the potentials, and with the fragilities of the corresponding supercooled liquids.Comment: 9 pages, 7 figures; new section added and error in potential parameters correcte

Structure and Stability of an Amorphous Metal

Using molecular dynamics simulations, with a realistic many-body embedded-atom potential, and a novel method to characterize local order, we study the structure of pure nickel during the rapid quench of the liquid and in the resulting glass. In contrast with previous simulations with pair potentials, we find more crystalline order and fewer icosahedra for slower quenching rates, resulting in a glass less stable against crystallization. It is shown that there is not a specific amorphous structure, only the arrest of the transition from liquid to crystal, resulting in small crystalline clusters immersed in an amorphous matrix with the same structure of the liquid.Comment: 4 pages, 4 ps figs., to appear in Phys. Rev. Let

Mobile Families and Other Challenges in the Design of the Millennium Cohort Study

The Millennium Cohort Study continues the tradition of Britain?s national longitudinal birth cohort surveys, but it has broken the design mould of being based on all births in a week. The specification that it should cover a year?s births provided the opportunity for some innovative design. This paper describes the disproportionately stratified design, based on a sample of electoral wards and the practicalities of implementing it. The need to sample offered the possibility of over representing populations of particular interest: children living in economically deprived areas, in areas where minority ethnic groups are concentrated, and in the smaller countries of the UK. Eligible families in sampled wards are selected from records held by the Department for Work and Pensions, who also subsequently administer an opt-out to families in sampled areas. Although the final analysis of the sampling process (and the substantive results) will not be ready until 2003, it will be possible to present an interim report on the experience of drawing the sample in this way, focusing particularly on England and Wales, where the survey started earlier. The number of children identified through the administrative records will be compared with those recorded in Birth Registration records, as far as ward boundary changes allow. The cases withdrawn before a sample can be issued to field are analysed by type of ward and type of claimant. A preliminary assessment of the coverage of the Child Benefit Register is offered in a comparison with data from vital registration. This exercise has so far only covered those wards in England where there have been no boundary changes between those used to define the sample in 1998 and those applying in 2000-2001 when the children were actually born. The extent of mobility in and out of target areas by families with children aged 6-9 months is also to be discussed. The strengths of using the Child Benefit register as a sampling frame have been confirmed. The difficulties have in some ways been less than anticipated, and the requirement of a geographically defined sample would have formed a challenge whatever method of sampling had been adopted

Engineering characterization of ground motion. Task I. Effects of characteristics of free-field motion on structural response

This report presents the results of the first task of a two-task study on the engineering characterization of earthquake ground motion for nuclear power plant design. The overall objective of this study is to develop recommendations for methods for selecting design response spectra or acceleration time histories to be used to characterize motion at the foundation level of nuclear power plants. Task I of the study develops a basis for selecting design response spectra, taking into account the characteristics of free-field ground motion found to be significant in causing structural damage

Nonconstant electronic density of states tunneling inversion for A15 superconductors: Nb3Sn

We re-examine the tunneling data on A15 superconductors by performing a generalized McMillan-Rowell tunneling inversion that incorporates a nonconstant electronic density of states obtained from band-structure calculations. For Nb3Sn, we find that the fit to the experimental data can be slightly improved by taking into account the sharp structure in the density of states, but it is likely that such an analysis alone is not enough to completely explain the superconducting tunneling characteristics of this material. Nevertheless, the extracted Eliashberg function displays a number of features expected to be present for the highest quality Nb3Sn samples.Comment: 11 pages, 11 figure