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Successive administrative policies, overlaid on the traditional communal land tenure system in the Qaukeni area of the Eastern Cape, have had the effect of tying people to the land and creating an environment that severely constrains opportunities for development. This article traces the influence of administrative changes on land allocation over the last century. It assesses the impact of the settlement pattern in the early 1980s on accessibility to basic facilities, services and development opportunities. In view of the severe conditions in the study area (internal push factors), coupled with reduced restrictions on movement to South African cities and a general urbanisation trend (external pull factors), population movements could have been expected both out of the region and to more accessible places within it. Primary research, using districts and administrative areas as the units of analysis, revealed that few of the expected changes had occurred in the period between 1982 and 1993. However, recent evidence shows that several of the anticipated changes are taking place. The article concludes that, notwithstanding recent trends, a combination of the land tenure system (in both rural and urban areas), a variety of place-related factors in rural areas, together with risk-spreading strategies on the part of households, continue to exert a strong influence in keeping people on the land, even though their existence is not subsistence based, but linked to the urban economy. [ABSTRACT FROM AUTHOR]

In 108 consecutive patients without abrupt vessel closure referred for repeat coronary angiography within 30 days of successful coronary intervention, 28 (26%) were found with restenosis at the treated site. None of the 27 patients who underwent stenting were found to have early restenosis; balloon angioplasty without stenting was the only independent predictor of early restenosis in patients with recurrent symptoms within 30 days of intervention. [ABSTRACT FROM AUTHOR]

A family of dinuclear cobalt complexes with bridging bis(dioxolene) ligands derived from 3,3,3′,3′-tetramethyl-1,1′-spirobis(indane-5,5′,6,6′-tetrol) (spiroH4) and ancillary ligands based on tris(2-pyridylmethyl)amine (tpa) has been synthesized and characterized. The bis(dioxolene) bridging ligand is redox-active and accessible in the (spirocat-cat)4-, (spiroSQ-cat)3-, and (spiroSQ-SQ)2- forms, (cat = catecholate, SQ = semiquinonate). Variation of the ancillary ligand (Mentpa; n = 0-3) by successive methylation of the 6-position of the pyridine rings influences the redox state of the complex, governing the distribution of electrons between the cobalt centers and the bridging ligands. Pure samples of salts of the complexes [Co2(spiro)(tpa)2]2+ (1), [Co2(spiro)(Metpa)2]2+ (2), [Co2(spiro)(Me2tpa)2]2+ (3), [Co2(spiro)(Me3tpa)2]2+ (4), [Co2(spiro)(tpa)2]3+ (5), and [Co2(spiro)(tpa)2]4+ (6) have been isolated, and 1, 4, and 6 have been characterized by single crystal X-ray diffraction. Studies in the solid and solution states using multiple techniques reveal temperature invariant redox states for 1, 2, and 4-6 and provide clear evidence for four different charge distributions: 1 and 2 are CoIII-(spirocat-cat)-CoIII, 4 is CoII-(spiroSQ-SQ)-CoII, 5 is CoIII-(spiroSQ-cat)-CoIII, and 6 is CoIII-(spiroSQ-SQ)-CoIII. Of the six complexes, only 3 shows evidence of temperature dependence of the charge distribution, displaying a rare thermally induced two-step valence tautomeric transition from the CoIII-(spirocat-cat)-CoIII form to CoII-(spiroSQ-cat)-CoIII and then to CoII-(spiroSQ-SQ)-CoII in both solid and solution states. This is the first time a two-step valence tautomeric (VT) transition has been observed in solution. Partial photoinduction of the VT transition is also possible in the solid. Magnetic and spectroscopic studies of 5 and 6 reveal that spiroconjugation of the bis(dioxolene) ligand allows electronic interaction across the spiro bridge, suggesting that thermally activated vibronic coupling between the two cobalt-dioxolene moieties plays a key role in the two-step transition evident for 3. [ABSTRACT FROM AUTHOR]