A neutron scattering study on the incommensurate-commensurate ϵ → ζ phase transition of the perovskite-type layer compound PAMC: A lock-in phase transition with a flipping modulation vector

An elastic neutron scattering experiment between 80 and 120 K has further elucidated the ?- and ζ-phases of PAMC and the ? → ζ phase transition. The temperature dependence of the incommensurate modulation vector $\text{q}\text{= (}\text{1}\text{3}\text{+ δ)}\text{b}{}^1$ of the ?-phase has been determined near the phase transition. At the phase transition the modulation vector locks-in at δ = 0, but below the transition it flips into the $\text{(}\text{b}{}^1\text{?}\text{c}{}^1\text{)}$ direction. The symmetry of ζ-PAMC is monoclinic and the A-centering of the normal δ-phase is partially recovered. Multiple and reversible twinning occurs. Pronounced discontinuities appear at the phase transition in the lattice parameters and reflection intensities.     

General features of the pp interaction at 12 GeV/c

Simple inclusive cross sections for $\text{p}\text{p}$ interactions at 12 GeV/c are given. The data cover prong cross sections, V⁰ production and resonances. Separation has been made into annihilation and non-annihilation modes. Some implications of the data are discussed. It is pointed out that the ratios of cross sections for $\text{?}{}^0\text{π}{}^{\mathrm{?}}$ production are independent of incident antiproton momentum in $\text{p}\text{p}$ annihilation processes, and that data at the highest available pp energies (ISR) tend to the same value.     

Numerical holographic reconstruction by a `projective transform?

A numerical method of holographic reconstruction of 2-dimensional fields is presented. Reconstructions are obtained indirectly, by generating the 2-dimensional Fourier transform of the field by using the slowness curve of the medium. Wideband data can be handled efficiently by this method, which also works in dispersive and anisotropic space. Examples of monochromatic and multifrequency holographic reconstructions are shown.     

The Coal Cutter as a Seismic Source in Channel Wave Exploration

The detection of faults in coal seams using underground seismic techniques is now well established. In this paper we propose the use of the coal cutter as a seismic source. Coal production, far from being disrupted by hole drilling and shot firing, is an integral part of the technique.     

Elemental analysis of human placenta by neutron irradiation and gamma-ray spectrometry (standard,prompt and fast-neutron)

Human placental tissue from 100 hospitalized deliveries were analysed for Ag, Al, As, Au, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, F, Fe, I, Hg, K, La, Mg, Mn, Mo, Na, Ni, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, V, W and Zn using a combination of pre-chemical separation of sodium with hydrated antimony pentoxide and instrumental neutron activation analysis. Boron and Si values were determined using prompt gamma-ray and fast-neutron techniques respectively. Analysis of NBS-SRM Bovine Liver 1577 and a pooled standard placental tissue for 33 elements showed a good agreement with most coefficients of variation less than or equal to 15%, and recoveries of 91–104%. Symmetrical distributions, were obtained for all elemental placental values. Only Cd(–) and Zn(+) showed statistically significant correlations with birth weight, gestational age and placental weight. The influence of cigarette smoking is considered a major factor in producing elevated cadmium levels in the placental tissue of smokers and passive smokers, and hence lower birth weights.     

A constitutive relation for compressible plastic materials

Summary In this note a yield criterion and its associated stress-strain increment relations dependent on isotropic pressure, are presented, for a non-hardening elastic-plastic compressible material.