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This paper suggests that, for developing countries, the creation of economic regulatory agencies, separate from the ministry in charge of water and sanitation, may not be a necessary or sufficient condition to stimulate large scale private involvement (PPPs) in the sector. The odds of an impact are higher for Latin American countries than other regions and for countries with higher income levels. They are also better when inflation is high. At the margin, the odds are unrelated to the contract type, except for greenfield projects, for which they may be contraindicated. 相似文献
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针对采厂矿车翻卸人工计数可靠性低、安全风险大等问题,提出一种矿车翻卸自动计数系统设计方案,以JRF33铁路车号识别装置为载体,以RS485为通讯协议,对采集数据进行统计分析。结果显示,计数系统运行良好,翻卸数据采集及时、准确、完整。系统对采矿原料运输数据统计、分析应用和生产指导有一定的指导意义。 相似文献
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A comparative study of the purification of betanin 总被引:3,自引:0,他引:3
Letícia Christina Pires GonçalvesMarco Aurélio de Souza Trassi Nathana Barbosa LopesFelipe Augusto Dörr Monica Teixeira dos SantosWilhelm Josef Baader Vani Xavier Oliveira Jr.Erick Leite Bastos 《Food chemistry》2012,131(1):231-238
Betanin is a natural pigment with antioxidant properties used as a food colourant. This work describes the spectrophotometric and chromatographic quantification of betanin (2S/15S) and its epimer isobetanin (2S/15R) in fresh beetroot juice, food-grade beetroot powder and betanin standard diluted in dextrin. Absorption spectra of all three samples were deconvoluted using a mixed three-function model. Food-grade beetroot powder has the largest amount of violet-red impurities, probably formed during processing. The purification of betanin from these complex matrices was carried out by seven different methods. Ion exchange chromatography was the most efficient method for the purification of betanin from all samples; however, fractions contain high amounts of salt. Reversed-phase HPLC as well as reversed-phase column chromatography also produced good results at a much faster rate. The longer retention time of isobetanin when compared to betanin in reversed-phase conditions has been investigated by means of quantum-mechanical methods. 相似文献
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Elizabeth A. Mack 《Papers in Regional Science》2014,93(1):3-29
This study evaluates the relationship between the spatial distribution of broadband providers and the presence of knowledge intensive firm clusters in US counties. Results highlight this relationship is heterogeneous and localized. In some places, broadband appears to be an essential link that enables knowledge firms to strategically locate in lower cost counties and in close proximity to major knowledge centres. In other places, the availability of broadband Internet connections are unable the negative externalities associated with locations in more remote areas of the country. From a policy perspective, this suggests that broadband should be viewed as a key component, but not the only component, of comprehensive local economic development plans. 相似文献
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This paper extends the seminal Blanchard and Katz regional labour market model to include interaction effects using a dynamic spatial panel data approach. Three key contributions of this extended model are: (i) the unrealistic assumption that regions are independent of one another no longer has to be made, (ii) the magnitude and significance of so‐called spillover effects can be empirically assessed, and (iii) both the temporal and spatial propagation of labour demand shocks can be investigated. Using annual data from 1986–2010 for 112 regions across eight EU countries, both the non‐spatial and spatial models are estimated. It is found that the majority of the spillover effects are highly significant. Consistent with economic theory, the impact of a region‐specific demand shock is largest in the region where the shock instigates. The shock also propagates to other regions, especially impacting the first and second‐order neighbours. 相似文献