The geology of the Archaean granitoid-greenstone terrane in the vicinity of Three Sisters, Barberton Greenstone Belt.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the degree of Doctor of PhilosophyThis thesis provides a comprehensive account of the geology of the Archaean granitoid-greenstone terrane centred around Three Sisters in the northeastern sector of the Barberton Mountain Land. The supracrustal succession in the region comprises a diverse variety of altered volcanic and sedimentary rock types that have been correlated with the principal lithostratigraphic units of the Barberton greenstone belt (BGB) as fellows: 1) schistose basic and ultrabasic lithologies correlated with the Theespruit Formation of the Gnverwacht Group are mainly developed in a narrow unit fringing the northern margin of the BGB; 2) ferruginous shale greywacke - banded iron-formation assemblages correlated with the Jheba and Belvue Road Formations constitute the dominant Fig Tree Group imks in the region. A sec «ence or silicic » .-stavolcaniclastic rocks, now altered to a variety of micaceous schists, occurs west, north ar.a northeast of Three Sisters. Viljoen and Viljoen (1970) cc rrela ted these schists ith the Theespruit Formation. In this study, the schists have been assigned'to a new lithostratigraphic unit, referred to as the Bien Venue Formation, which forms the uppermost formation of the Fig Tree Group in the northeastern part of the BGB. Isotopic studies on zircons indicate that the schists have an age of 3256 ± Ma, which is some 200 Ma younger titan the most recent age estimates for the lower portions of the Gnverwacht Group. Chemically, the silicic schists resemble calc-alkaline rocks found in modem arcs, suggesting that the Bien Venue Formation represents a period of arc-like volcanism; and 3) conglomeratic and quartzitic rocks constitute the dominant lithologies within the Moodies Group, which uncoriorroably or paraconformably overlies lithologies of the Fig Tree and Onverwacht Groups. North of the BGB is a complex suite of granitoid rocks, previously investigated by Robb et al. (1983) who defined a large (—60 kn ng and —6 km wide), elongate plutonic body of tonalitic-to-trondhjemitic composition known as the Stentor pluton. It was suggested that this pluton is correlatable with the irondhjemite gneiss plutons that intrude the southwestern parts of the BGB. Field evidence indicates, however, that the Stentor pluton forms a much smaller (* .14 km long and ~ 4 km wide) ovoid body located immediately north of the village of Louw’s Creek. Furthermore, the pluton consists of equigranular-textured graiodiorite-adamcllite, totally unlike any of the trondhjemite gneisses. In terms of texture, mineralogy and chemical composition, the Stentor pluton closely resembles the Hebron and Berlin plutohs which constitute a phase of the Nelspruit batholith. Thus, it is concluded that the Stentor pluton also forms an integral part of the batholith. Three deformation phases have been identified. The regional event affected all stratigraphic units in response to a northerly oriented compressions! stress and gave rise to east-northeasterly trending, tight-.« 5soclinal, upright and north-verging folds that are bounded by southward-dipping longitudinal reverse faults. The regional deformation occurred both prior and subsequent to the emplacement of the Stentor pluton at circa 3100 Ma. Deformation associated with the diapiric intrusion of the Stentor pluton into the greenstone assemblage during the regional deformation pnase, led to the formation of large-scale folds that have modified earlier formed structures. The final deformation episode is manifested by the presence of nortnwest- to northeast-striking, oblique-slip normal faults that exhibit both left- and right-lateral strike-slip components.AC 201

How frequently do consumer prices change in Austria? Evidence from micro CPI data

Based on individual price records collected for the computation of the Austrian CPI, average frequencies of price changes and durations of price spells are estimated to characterize price setting in Austria. Depending on the estimation method, prices are unchanged for 10 to 14 months on average. We find strong heterogeneity across sectors and products. Price increases occur only slightly more often than price decreases. The typical size of a price increase (decrease) is 11 (15) percent. The aggregate hazard function of prices is decreasing with time. Besides heterogeneity across products and price setters, this is due to oversampling of products with a high frequency of price changes. Accounting for unobserved heterogeneity in estimating the probability of a price change with a fixed-effects logit model, we find a positive effect of the duration of a price spell. During the Euro cash changeover the probability of price changes was higher. JEL Classification: C41, D21, E31, L11consumer prices, duration of price spells, frequency and synchronization of price changes, sticky prices

THE CELLULAR RECEPTOR (CD4) OF THE HUMAN IMMUNODEFICIENCY VIRUS IS EXPRESSED ON NEURONS AND GLIAL CELLS IN HUMAN BRAIN

The peculiar tropism of the human immunodeficiency virus (HIV) for T helper lymphocytes can be explained by a specific interaction between the virus and the CD4 molecule on these cells (1, 2). The tropism for T lymphocytes, however, can hardly account for the early brain infection observed in some AIDS (acquired immune deficiency syndrome) patients (3, 4). Since CD4 is also expressed on virus-susceptible non-T cell lines we wondered whether an additional expression site of CD4 could be demonstrated in neural tissue (5). To this end, CD4 expression in brain was analyzed with several different anti-CD4 mAbs, and using a CD4-specific cDNA probe in Northern blot analyses . CD4' cells and CD4-specific mRNA were found in the cerebellum, thalamus, and pons. The reactive cells could be identified as neurons as well as glial cells

Flow motion waves with high and low frequency in severe ischaemia before and after percutaneous transluminal angioplasty

Study of objective - The aim was to evaluate skin flux and prevalence of low and high frequency flow motion waves in patients with severe ischaemia due to peripheral arterial occlusive disease before and after percutaneous transluminal angioplasty (PTA) with and without local thrombolysis. Design - Flow motion was recorded by the laser Doppler technique at the dorsum of the foot before, one day, and one month after PTA. The results were separately analysed in patients with successful and unsuccessful treatment. Subjects - 18 patients with rest pain or incipient gangrene were included. Mean pretreatment systolic ankle pressure was 55.8(SD 25.5) mm Hg, and mean transcutaneous Po2 at 43°C was 5.2(9.4) mm Hg. Arteriography revealed relevant stenoses or occlusions of the femoropopliteal and calf arteries. Measurements and results - Before treatment two patterns of flow motion with characteristic frequency ranges were observed at the foot dorsum and at a probe temperature of 32°C: low frequency (LF) waves with a mean frequency of 2.2(0.5) cycles·min−1 and a mean amplitude of 0.73(0.42) arbitrary units (AU) and high frequency (HF) waves with a mean frequency of 22.6(4.2) cycles·min−1 and a mean amplitude of 0.39(0.33) AU. PTA was successful in 11 of the 18 patients. After successful treatment, prevalence of HF waves decreased from 10/11 to 4/11 cases (p<0.00l), but remained nearly unchanged after failed procedure. Prevalence of LF waves before and after PTA did not differ significantly. Conclusions - Our data support the hypothesis that HF waves represent a reaction of skin microcirculation to severe ischaemia. With reference to animal studies it is proposed that HF waves originate from terminal arterioles. They may function as a compensatory mechanism of flow regulation involved in pathophysiology of ischaemi

Patterns and Determinants of Price Changes: Analysing Individual Consumer Prices in Austria

We provide empirical evidence on the degree and characteristics of price rigidity in Austria by estimating the average frequency of price changes and the duration of price spells from a large data set of individual price records collected for the computation of the Austrian CPI