Low temperature annealing and cathodoluminescence studies of type 1 chondrule compositions

Preliminary results indicate that the yellow luminescing mesostases in type I chondrules can be altered by the effects of the low level thermal metamorphism. Although heat alone was insufficient to alter the CL, reheating for geologically relevant periods could have the same results as we obtained in a second series of experiments with water present. It is known that both water and solutions of sodium metasilicate greatly accelerate the devitrification of glasses. The results of the experiments that will be repeated should further clarify how the CL changes with increased thermal alteration

Does trade liberalization enhance income growth and equity in Zimbabwe?: the role of complimentary policies

Using an agriculture-focused CGE model for Zimbabwe with 1991 as base period, this paper examines quantitatively the income and equity effects of trade liberalization in isolation and in conjunction with potentially complementary changes in fiscal and land policies. Trade policy reform alone (dismantling of import and foreign exchange controls, and reduction of import taxes to a low uniform rate) is shown to increase aggregate disposable household income significantly. However, the least income gain accrues to smallholder farm households, which account for about four-fifths of the poor in Zimbabwe, so the equity impact is unfavorable. Concurrent implementation with specific changes in government expenditure and tax policies and two alternative stylized land redistribution schemes yields differing outcomes in terms of aggregate household income growth and its distribution.Trade liberalization Econometric models., Zimbabwe Economic policy., Income distribution Zimbabwe., Fiscal policies ,

Wheat policy reform in Egypt: adjustment of local markets and options for future reforms

Many developing countries are in transition from a state-dominated to a more market-oriented economy. Because agriculture is of primary importance in most developing countries,the state is usually heavily involved in both input and output markets and in controlling prices and trade. However, concerns that market liberalization will result in higher consumer food prices and hurt the poor means that many countries, such as Egypt, have, at best, undertaken only partial agricultural sector reforms. It has been argued that such concerns are unwarranted and that further market liberalization is not only needed, but achievable without increasing impoverishment. IFPRI Research Report 115 sheds light on these critical issues through an analysis of wheat policy reform in Egypt.Consumers Egypt., Wheat trade Government policy Egypt., Food supply Government policy Egypt., Agricultural policies, Markets Prices., Developing countries. ,

Macroeconomic policy reforms and agriculture: towards equitable growth in Zimbabwe

"This report investigates the income and equity effects of macroeconomic policy reforms in Zimbabwe, emphasizing linkages between macroeconomic policies and agricultural performance and agriculture's influence on aggregate income and its distribution. Analyses focus on reform of the foreign trade regime, public expenditure, and tax policy, along with the potential benefits of combining these structural changes with various land reform scenarios. The study uses a CGE model that provides a policy simulation laboratory in which exogenous policy changes are analyzed for their economywide income and equity effects. The report highlights the need for policy complementarities in Zimbabwe that can contribute to equitable growth. It should be of interest not only to those concerned with recent economic developments in Zimbabwe but also to those concerned with the broader issues of macroeconomic reform and its ultimate effects." Author's AbstractMacroeconomics, Structural adjustment (Economic policy), Agriculture Economic aspects Zimbabwe, Agriculture and state,

The occurrence of blue luminescing enstatite in E3 and E4 chondrites

Two compositional types of enstatite that emit cathodoluminescence (CL) are known to exist in E3 and E4 chondrites. The first type consists of the most common enstatites that are relatively FeO-poor and emit a red CL. Their CL is apparently activated by the presence of MnO and Cr2O3 in concentrations of 0.2 and 0.6 weight percent. The second type of enstatite is nearly FeO-free, contains no MnO or Cr2O3 and emits a blue CL. The origin of these two types of enstatite and their accompanying chemical and CL differences has long been a subject of discussion. Leitch and Smith first observed to two types and felt the compositional differences were too great to have formed under the same conditions. They postulated the two types of enstatite formed on separate parent bodies and were mixed when these bodies collided. McKinley et al. observed a continuous range of compositions between blue luminescing and red luminescing enstatites and concluded the two types of enstatite formed evidence that blue luminescing pyroxenes were relics that did not completely melt during the heating event which melted other precursor grains, and are distinct from the red CL pyroxene in the chondrules in E chondrites. In order to further clarify the nature and origin of the pyroxene that emits blue CL, the sections listed in another work were examined for the occurrence of blue luminescing enstatite

Experimentally reproduced relict enstatite in porphyritic chondrules of enstatite chondrite composition

Experiments are presented that test a model for the origin of porphyritic pyroxene (PP) chondrules in enstatite chondrites that contain phenocrysts of enstatite with blue cathodoluminescence (CL) set in a matrix of radial, dendritic enstatite with red CL. Established one-atmosphere, gas-mixing techniques were used. Relict enstatite phenocrysts with blue CL in a matrix of coarsely radial to dendritic enstatite with red CL were successfully produced. The relict crystals are preserved in runs with a melt time of 36 minutes or less at 1537 C. The relicts remain angular with smooth crystal/melt interfaces, and thus melting has occurred uniformly. Partial melting does occur along fractures produced when the blue CL enstatite was initially grown and cooled through the proto/ortho enstatite transition with the attendent volume change. There is either reaction with the melt and diffusion of Mn and Cr into the blue CL En, or there is an overgrowth of red CL En along the fractures. The bulk of the relicts remain blue. The melt enclosing the relicts crystalized to a coarsely radial to dendritic to micro porphyritic texture comprised of enstatite that has a bright red CL with decreasing melt time. The blue CL En has Mn and Cr contents at or below detection limits of the electron probe as described in earlier studies and in natural blue CL En. In the red CL En in this study, the Mn, Al2O3, and Cr are at previously observed levels and the levels change rapidly

On the origin of enstatite chondrite chondrules based on their petrography and comparison with experimentally produced chondrules

The recent discovery of several types 3 and 4 enstatite chondrites (EC) in the Antarctic collection increases greatly the ability to compare unaltered, naturally-formed EC chondrules with chondrules produced experimentally from melts of enstatitic chondrule composition. Because these discoveries are so recent we have undertaken the task of characterizing these chondrules for purposes of comparison. We have looked at several new Antarctic E3 chondrites and Qingzhen. They all have numerous chondrules with well defined outlines and readily identifiable textures. All have mostly porphyritic chondrules, but there are differences in the size and kinds of textures. Radial pyroxene, barred/dendritic px, and cryptocrystalline chondrules are present in differing amounts with one exception

'Mindless markers of the nation': The routine flagging of nationhood across the visual environment

The visual environment has increasingly been used as a lens with which to understand wider processes of social and economic change with studies employing in-depth qualitative approaches to focus on, for example, gentrification or trans-national networks. This exploratory paper offers an alternative perspective by using a novel method, quantitative photo mapping, to examine the extent to which a particular socio-cultural marker, the nation, is ‘flagged’ across three contrasting sites in Britain. As a multi-national state with an increasingly diverse population, Britain offers a particularly fruitful case study, drawing in debates around devolution, European integration and Commonwealth migration. In contributing to wider debates around banal nationalism, the paper notes the extent to which nations are increasingly articulated through commerce, consumption and market exchange and the overall significance of everyday markers (signs, objects, infrastructure) in naturalising a national view of the world