The structure of 2,3,5-trisubstituted 2-pyrrolin-4-ones

Compounds previously reported to be 2,3,5-trisubstituted 2-pyrrolin-4-ones are shown to have 5,5′-dimeric structures.     

Dynamic dielectric analysis of solids

An automated technique has been developed which enables a rapid determination of the dielectric properties of a material over a wide range of temperatures and frequencies. The speed of data acquisition and the range of temperature and frequencies that can be investigated in a single experiment using this technique, exceed the capabilities of techniques currently employed for dielectric analysis. Frequencies for dielectric measurements can be pre-selected in increments over the range 50 Hz-1 MHz. Temperature range for these measurements extends from 25°C to 800°C. The present technique, which features extensive automation in data acquisition and processing, is illustrated by measurements on minerals and shales. The dynamic nature of the above technique also facilitates effective coupling with conventional thermal analysis techniques.     

Uncovering Organizational Hierarchies

This paper adapts a procedure, canonical analysis of asymmetry,originally defined by Gower (1977) to the analysis of hierarchicalproperties in organizational structures. Its application is demonstratedusing two available data sets, Freeman and Freeman's (1980) data on computercommunication and Krackhardt's (1987) data on advice-giving and getting inan organization.     

Man-made materials—an exciting area for hyperfine-interaction investigations

Summary Man-made low-dimensional magnetic systems including surfaces, interfaces and multilayers, have attracted a great amount of attention in the past decade because, as expected, the lowered symmetry and coordination number offer a variety of opportunities for inducing new and exotic phenomena and so hold out the promise of new device applications. Local spin density functional (LSDF)ab initio electronic-structure calculations employing the full-potential-linearized augmented-plane-wave (FLAPW) method have played a key role in the development of this exciting field by not only providing a clearer understanding of the experimental observations but also predicting new systems with desired properties. One of the striking successes of theory in the last decade has been the calculation of hyperfine fields at surfaces and interfaces. Concurrently, several groups have followed the pioneering work of Korecki and Gradmann and have measured hyperfine fields at surfaces and interfaces. In this paper, we review new features of hyperfine-interaction investigations in man-made materials which emphasizes how the close interplay of theoretical determinations and experiment are essential because the hyperfine field is not proportional to the magnetization and so interpretations of experiment are totally dependent on theory. Paper presented at ICAME-95, Rimini, 10–16 September 1995.     

Temperature dependence of NMR spectrum of powdered cobalt

NMR spectra of powdered cobalt were obtained from 290 to 580 K. The hcp phase of powdered, and coarse grained bulk samples give different results, indicating effects due to magnetoelastic interactions of the domain walls with lattice defects.     

Renormalization of non-abelian gauge theories in curved space-time

We use indirect, renormalization group arguments to calculate the gravitational counterterms needed to renormalize an interacting non-abelian gauge theory in curved space-time. This method makes it straightforward to calculate terms in the trace anomaly which first appear at high order in the coupling constant, some of which would need a 4-loop calculation to find directly. The role of gauge invariance in the theory is considered, and we discuss briefly the effect of using coordinate-dependent gauge-fixing terms. We conclude by suggesting possible applications of this work to models of the very early universe.     

Defect state model for localized excitations in LiF

We find that a defect state treatment of localized excitations in LiF within the local density functional formalism accounts remarkably well for the observed experimental (core plus optical gap) excitations — in contrast to the failure of the one-electron band model. We show that when electron relaxation, self-interaction and charge polarization effects are taken into account by treating the excitation as a localized points defect, the improved band model predicts the correct excitation and interband states.