Prediction of Peak Expiratory Flow Rates in Stunted Children

A CAJM article on stunted growth in Malawian children.Objective: To assess the effect of stunting on peak expiratory flow rates (PEFR) in Malawian children. Design: Cross sectional study. Setting: Two public primary schools randomly selected in Blantyre, the largest city in Malawi. Subjects: 266 boys and 273 girls aged six to 14 years.Main Outcome Measures: PEFR, height, weight and age of children were determined using standard techniques. Nutritional status of children was assessed using WHO/NCHS height for age, weight for age and weight for height reference standards. Results: The data of PEFR were analysed by regression on age and stature. One hundred children (18.6%) were classified as stunted. None of them was under weight or wasted. The equations for prediction of PEFR were calculated separately for stunted and non-stunted children. Stature was a significant predictor of PEFR values in both groups of children. The differences between stunted and non-stunted children of both sexes in slopes and intercepts of the regression lines of PEFR on stature were non-significant. Stunted children of both sexes had significantly lower PEFR than their counterparts with normal height for age index. Conclusions: Stunting in Malawian children aged six to 14 years is associated with decreased rate of development of PEFR in proportion to linear growth retardation. Prediction equations calculated for children with normal height for age index can be used for assessment of PEFR in stunted children

Transport properties and the anisotropy of Ba_{1-x}K_xFe_2As_2 single crystals in normal and superconducting states

The transport and superconducting properties of Ba_{1-x}K_xFe_2As_2 single crystals with T_c = 31 K were studied. Both in-plane and out-of plane resistivity was measured by modified Montgomery method. The in-plane resistivity for all studied samples, obtained in the course of the same synthesis, is almost the same, unlike to the out-of plane resistivity, which differ considerably. We have found that the resistivity anisotropy \gamma=\rho_c /\rho_{ab} is almost temperature independent and lies in the range 10-30 for different samples. This, probably, indicates on the extrinsic nature of high out-of-plane resistivity, which may appear due to the presence of the flat defects along Fe-As layers in the samples. This statement is supported by comparatively small effective mass anisotropy, obtained from the upper critical field measurements, and from the observation of the so-called "Friedel transition", which indicates on the existence of some disorder in the samples in c-direction.Comment: 5 pages, 5 figure

Theoretical conformational analysis of organophosphorus compounds

Published data on the theoretical conformational analysis of acyclic tri- and tetracoordinate phosphorus compounds by quantum-chemical methods are generalised and systematised. Theoretical results are compared with experimental data for a wide range of such compounds. The main characteristics and fine conformational details of their structures are considered. © 2005 Russian Academy of Sciences and Turpion Ltd

Theoretical study of H complexes of tetracoordinated phosphorus compounds

Energies of formation of complexes of hydrogen fluoride with compounds of tetracoordinated phosphorus, charge transfers in complexing, and other characteristics of these reactions calculated by CNDO/2 methods agree well with the measured values. © 1979 Plenum Publishing Corporation

Spontaneous breaking of four-fold rotational symmetry in two-dimensional electronic systems explained as a continuous topological transition

The Fermi liquid approach is applied to the problem of spontaneous violation of the four-fold rotational point-group symmetry ($C_4$) in strongly correlated two-dimensional electronic systems on a square lattice. The symmetry breaking is traced to the existence of a topological phase transition. This continuous transition is triggered when the Fermi line, driven by the quasiparticle interactions, reaches the van Hove saddle points, where the group velocity vanishes and the density of states becomes singular. An unconventional Fermi liquid emerges beyond the implicated quantum critical point.Comment: 6 pages, 4 figure

Theoretical Aspects of Science with Radioactive Nuclear Beams

Physics of radioactive nuclear beams is one of the main frontiers of nuclear science today. Experimentally, thanks to technological developments, we are on the verge of invading the territory of extreme N/Z ratios in an unprecedented way. Theoretically, nuclear exotica represent a formidable challenge for the nuclear many-body theories and their power to predict nuclear properties in nuclear terra incognita. It is important to remember that the lesson learned by going to the limits of the nuclear binding is also important for normal nuclei from the neighborhood of the beta stability valley. And, of course, radioactive nuclei are crucial astrophysically; they pave the highway along which the nuclear material is transported up in the proton and neutron numbers during the complicated synthesis process in stars.Comment: 26 ReVTeX pages, 11 Postscript figures, uses epsf.sty, to be published in: Theme Issue on Science with Beams of Radioactive Nuclei, Philosophical Transactions, ed. by W. Gelletl

Field dependence of the adiabatic temperature change in second order phase transition materials: Application to Gd

The field dependence of the adiabatic temperature change Tad of second order phase transition materials is studied, both theoretically and experimentally. Using scaling laws, it is demonstrated that, at the Curie temperature, the field dependence of Tad is characterized by H1/. Therefore, as the magnetic entropy change SM follows a H(1−)/ power law, these two dependencies coincide only in the case of a mean field model. A phenomenological construction of a universal curve for Tad is presented, and its theoretical justification is also given. This universal curve can be used to predict the response of materials in different conditions not available in the laboratory (extrapolations in field or temperature), for enhancing the resolution of the data and as a simple screening procedure for the characterization of materialsThis work was supported by the Spanish Ministry of Science and Innovation and EU FEDER (Grant No. MAT 2007-65227), and the PAI of the Regional Government of Andalucía Grant No. P06-FQM-01823 .Peer reviewe

Stereochemistry of seven-membered heterocycles: XLII. A theoretical study of stereochemistry of H complexes formed by conformationally nonuniform 2-R-1,3-dioxacyclohept-5-enes with some proton donors

According to semiempirical AM1 calculations, the stability of the boat and twist forms of 2-R-1,3-dioxacyclohept-5-enes depends on the size of substituents at the acetal carbon atom. The twist form gives diastereomeric H complexes with chloroform and methanol of the cis and trans structure, containing monocentered hydrogen bonds, whereas the chair conformation preferably forms complexes with a two-centered hydrogen bond. Based on theoretical data (ΓOH, ΔH, geometry of complexes), the specific features of H complexes of the conformers in electrophilic addition and cycloaddition were revealed. Considerable preferableness of the exo attack of the diastereotopic double bond in the H complex having the chair form is due to the steric accessibility of the exo side, whereas in the complexes of the twist form the facial selectivity is appreciably lower

Tunnelling Studies of Two-Dimensional States in Semiconductors with Inverted Band Structure: Spin-orbit Splitting, Resonant Broadening

The results of tunnelling studies of the energy spectrum of two-dimensional (2D) states in a surface quantum well in a semiconductor with inverted band structure are presented. The energy dependence of quasimomentum of the 2D states over a wide energy range is obtained from the analysis of tunnelling conductivity oscillations in a quantizing magnetic field. The spin-orbit splitting of the energy spectrum of 2D states, due to inversion asymmetry of the surface quantum well, and the broadening of 2D states at the energies, when they are in resonance with the heavy hole valence band, are investigated in structures with different strength of the surface quantum well. A quantitative analysis is carried out within the framework of the Kane model of the energy spectrum. The theoretical results are in good agreement with the tunnelling spectroscopy data.Comment: 29 pages, RevTeX, submitted in Phys.Rev.B. Figures available on request from [email protected]