Complex relativity and real solutions. I: Introduction

This is the first of a series of papers on complex spaces and their use in complex relativity. The basic aim is to develop the theory of complex relativity but only insofar as it helps in obtaining, and understanding, real solutions of Einstein's vacuum equations as slices of complex solutions. In this first paper, specific aims of the whole series are first presented. The basic equations and key entities, which are used later, are presented. The basic relativistic language used is that of Newman and Penrose. Included is a discussion of a number of important properties which arise in the development of the basic equations and key concepts, these properties being mainly ones which are not apparent in standard real formulations.     

Quality assessment in in vivo NMR spectroscopy: I. Introduction,objectives, and activities

By enabling noninvasive measurements of tissue biochemistry, nuclear magnetic resonance spectroscopy (MRS) provides a unique means of characterizing tissues. Differences in equipment, techniques, and methodology between different laboratories cause major difficulties when comparing results, whether from measurements of tissue metabolism, or from the effects of different therapies. This is of concern in critically evaluating work from different laboratories and centres, causing potential difficulties in reproducing results, limiting the establishment of MRS as a standard method of diagnosis and of characterising disease and response to therapy in the laboratory and clinic. It also poses particular problems in establishing the multicentre clinical trials of MRS that are now required to provide adequate statistical power in confirming the encouraging preliminary clinical observations. These difficulties arise principally from imperfect localization of signal from selected regions of interest in the body, and from the subsequent analyses of the MRS spectra. Improvement is possible by establishing agreed procedures for test measurements and for data analysis, and by using appropriate test objects and test substances to establish the quality of measurements. A concerted research project on characterisation of biological tissues by NMR, principally concerned with MR imaging (MRI), was activated in 1984 by the European Economic Community as part of its third Medical and Health Research Programme, under the auspices of the Biomedical Engineering Concerted Actions' Committee (COMAC-BME). In 1988, this project was prolonged for 5 years, when the programme was expanded to encompass MRS. A series of five accompanying papers describes (a) the test protocols and objects agreed for assessing the quality of volume selective MRS measurements; (b) the experimental trials performed for a multicentre evaluation of these procedures on experimental and clinical systems; and (c) the results of a joint quantitative data analysis study on in vivo NMR time-domain test signals.     

Sputtering of ordered nickel-aluminium alloys: I. Introduction and preferential sputtering of Ni3Al

A combination of several surface-sensitive microanalytical techniques have been applied to the study of selective or preferential sputtering by inert gas ion bombardment of aluminium from binary ordered nickel-aluminium alloys. Two discrete intermetallic compounds, Ni₃Al (this paper) and NiAl (the companion paper) have been examined in order to provide information regarding the contribution of surface binding states to sputter mechanisms. The use of atom-probe field-ion microscopy for analysis of ion-sputtered surfaces has permitted the depth of bombardment-induced composition profiles to be estimated and comparisons to be drawn between these depth profiles and those obtained by conventional surface analysis techniques. Studies of preferential sputtering in ordered structures have provided information through atom-probe analysis of fundamental and superlattice oriented specimens about composition profiles and bombardment-induced disordering processes. Consideration of these data have led to conclusions that two distinct “equilibria” may be involved in the formation of super-induced altered layers.     

Macrosonics in industry 1. Introduction

This paper reviews the use of sonic power to produce various permanent effects in a treated medium. These effects generally require very high powers for their initiation, hence the use of term macrosonics. The paper is the first in a series on the industrial applications of macrosonics.     

Bremsstrahlung statistics. I

The evolution of the bremsstrahlung density matrix is considered for scattering of a nonrelativistic electron beam by randomly distributed potentials. A system of equations for the first two moments of the density matrix is considered in the weak nonlinearity approximation, and solutions are given for coherent initial photon statistics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 92–97, November, 1978.     

Relativistic Cosmology. I

The paper presents some general relations obtaining in relativistic cosmology. It appears from these that a simple change over to anisotropy without the introduction of spin does not solve any of the outstanding difficulties of isotropic cosmological models.     

Inertial structure. I

The desirability and possibility to generalize space-time structure to non-Euclidean spaces is investigated. To this end, the two basic notions of inertial motion and relativity are revealed. Several relevant statements about kinematics on spaces of constant curvature are pointed out.