High-speed Civil Transport Aircraft Emissions

Estimates are given for the emissions from a proposed high speed civil transport (HSCT). This advanced technology supersonic aircraft would fly in the lower stratosphere at a speed of roughly Mach 1.6 to 3.2 (470 to 950 m/sec or 920 to 1850 knots). Because it would fly in the stratosphere at an altitude in the range of 15 to 23 km commensurate with its design speed, its exhaust effluents could perturb the chemical balance in the upper atmosphere. The first step in determining the nature and magnitude of any chemical changes in the atmosphere resulting from these proposed aircraft is to identify and quantify the chemically important species they emit. Relevant earlier work is summarized, dating back to the Climatic Impact Assessment Program of the early 1970s and current propulsion research efforts. Estimates are provided of the chemical composition of an HSCT's exhaust, and these emission indices are presented. Other aircraft emissions that are not due to combustion processes are also summarized; these emissions are found to be much smaller than the exhaust emissions. Future advances in propulsion technology, in experimental measurement techniques, and in understanding upper atmospheric chemistry may affect these estimates of the amounts of trace exhaust species or their relative importance

Cross-border insolvencies as a global economic problem

As a result of the continuing expansion of international trade and investment, there has been an increase in the occurrence of cross-border insolvencies. National insolvency laws have not kept pace with the trend, and there is a need to develop an efficient and fair system for the administration of cross-border insolvencies. The lack of predictability in the handling of cross-border insolvency cases impedes capital flow and constitutes a disincentive to cross-border investment. The object of the Cross-Border Insolvency Act is to create provisions for a fair framework to address instances of cross-border insolvency effectively. It is based on UNCITRAL’s Model Law on Cross-Border Insolvency. The practitioner-inspired solutions that the South African legislation offers are satisfactory and definitely an improvement on the common law position. The only contradiction is that the South African approach towards solving the complicated problems of cross-border insolvencies improves the position of foreign creditors, foreign representatives and foreign courts, while it is still doubtful how foreign courts will treat South African creditors. From this point of view the lack of predictability in the handling of cross-border insolvencies is still subject to criticism as a disincentive to cross-border investment

Die beskerming van skuldeisers ingevolge artikel 34 van die Insolvensiewet na ’n skikkingsooreenkoms

Uit teks: Artikel 34 van die Insolvensiewet 24 van 1936 handel oor die nietige verkoop van ’n besigheid. Artikel 34(1) bepaal dat indien ’n handelaar ’n besigheid wat aan hom behoort, of die klandisie van so ’n besigheid, of goedere of eiendom wat ’n deel daarvan is, oordra ingevolge ’n kontrak (behalwe in die gewone loop van daardie besigheid of tot die versekering van die betaling van ’n skuld), en so ’n handelaar publiseer nie die kennisgewings wat in die artikel voorgeskryf word nie, dan is so ’n oordrag nietig teenoor sy skuldeisers vir ’n tydperk van ses maande na die oordrag en nietig teenoor die kurator van sy boedel indien sy boedel te enige tyd binne daardie ses maande tydperk gesekwestreer word. Vir hierdie doeleindes beteken “oordrag” ook die werklike of fiktiewe oordrag van besit: Die handelaar hoef dus nie fisies besit van die bedoelde goed aan die ander party oorgedra het nie (a 34(4)). Sodra ’n kennisgewing ingevolge artikel 34(1) gepubliseer word, word elke gelikwideerde skuld van die handelaar in verband met die bedoelde besigheid wat op ’n toekomstige dag invorderbaar sou word, dadelik invorderbaar as die betrokke skuldeiser betaling van die skuld eis (a 34(2))

Chaos and crises in a model for cooperative hunting: A symbolic dynamics approach

In this work we investigate the population dynamics of cooperative hunting extending the McCann and Yodzis model for a three-species food chain system with a predator, a prey, and a resource species. The new model considers that a given fraction sigma of predators cooperates in prey's hunting, while the rest of the population 1-sigma hunts without cooperation. We use the theory of symbolic dynamics to study the topological entropy and the parameter space ordering of the kneading sequences associated with one-dimensional maps that reproduce significant aspects of the dynamics of the species under several degrees of cooperative hunting. Our model also allows us to investigate the so-called deterministic extinction via chaotic crisis and transient chaos in the framework of cooperative hunting. The symbolic sequences allow us to identify a critical boundary in the parameter spaces (K, C-0) and (K, sigma) which separates two scenarios: (i) all-species coexistence and (ii) predator's extinction via chaotic crisis. We show that the crisis value of the carrying capacity K-c decreases at increasing sigma, indicating that predator's populations with high degree of cooperative hunting are more sensitive to the chaotic crises. We also show that the control method of Dhamala and Lai [Phys. Rev. E 59, 1646 (1999)] can sustain the chaotic behavior after the crisis for systems with cooperative hunting. We finally analyze and quantify the inner structure of the target regions obtained with this control method for wider parameter values beyond the crisis, showing a power law dependence of the extinction transients on such critical parameters

Photonic realization of the relativistic Kronig-Penney model and relativistic Tamm surface states

Photonic analogues of the relativistic Kronig-Penney model and of relativistic surface Tamm states are proposed for light propagation in fibre Bragg gratings (FBGs) with phase defects. A periodic sequence of phase slips in the FBG realizes the relativistic Kronig-Penney model, the band structure of which being mapped into the spectral response of the FBG. For the semi-infinite FBG Tamm surface states can appear and can be visualized as narrow resonance peaks in the transmission spectrum of the grating