34 research outputs found
Critical Behaviour of Structure Factors at a Quantum Phase Transition
We review the theoretical behaviour of the total and one-particle structure
factors at a quantum phase transition for temperature T=0. The predictions are
compared with exact or numerical results for the transverse Ising model, the
alternating Heisenberg chain, and the bilayer Heisenberg model. At the critical
wavevector, the results are generally in accord with theoretical expectations.
Away from the critical wavevector, however, different models display quite
different behaviours for the one-particle residues and structure factors.Comment: 17 pp, 10 figure
Administração e teorias das organizações contemporâneas: rumo a um humanismo radical crítico?
Biophysical interactions in tropical agroforestry systems
sequential systems, simultaneous systems Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interac-tions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems. In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offse
Biomarkers of a five-domain translational substrate for schizophrenia and schizoaffective psychosis
Collected Works of Erasmus, Volume 4, The Correspondence of Erasmus, Letters 446 to 593: 1516 to 1517
Transforming internal corporate communications: the power of symbolic gestures and barriers to change
Reviews evidence to support the view that improved internal communication facilitates business success. Details the content of what have been identified as successful internal communications programmes. Focuses on those behaviours which produce improved interpersonal relationships in the workplace, and which could be widely emulated by managers seeking to promote good practice in their own organizations. Considers attitudinal barriers to the implementation of such approaches