首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 672 毫秒
1.
ABSTRACT Canadian poverty rates have persisted at disappointingly high levels despite almost 15 years of continuous economic growth. The problem is exacerbated by some communities and neighborhoods having exceedingly high poverty, including very high rates for vulnerable demographic groups, such as aboriginals and recent immigrants. We investigate low‐income rates (poverty rates) for 2,400 Canadian “communities” over the 1981–2001 period. By focusing on communities, we fill a void in the related Canadian literature, which tends to focus on individuals, case studies, or more aggregate measures, such as provinces. Our approach allows us to assess the role of place‐based policies. Particular attention is given to communities with differing shares of aboriginal Canadians and recent immigrants. One novel feature is our analysis of both “short‐term” and “long‐term” causes of differential community poverty rates. The results suggest that community low‐income rates are more affected by initial economic conditions in the short term, with certain demographic factors becoming relatively more important in the long run.  相似文献   

2.
In the last year, a central issue in regional economic growth debate has been represented by the empirical analysis of Verdoorn's law related to the long‐term dynamic relationship between the rate of growth in output and the productivity growth due to increasing returns. Several papers have tested Verdoorn's law on European countries as well as many other world economies. Recently, attempts have been made to provide foundations for a spatial version of the original law specification. The main contributions were dedicated to the inclusion of spatial dependence in the economic model. Surprisingly, in the literature on Verdoom's law the analysis of the spatial heterogeneity is not often considered. The aim of this paper is the regional analysis of the spatial dependence and heterogeneity in Verdoorn's law, identifying spatial regimes that can be interpreted as clusters of productivity growth in European regions at NUTS 2 level. To pursue this objective, an optimization algorithm for the identification of groups is used. This constitutes a modified version of Simulated Annealing.  相似文献   

3.
The majority of the literature on fiscal decentralization has tended to stress that the greater capacity of decentralized governments to tailor policies to local preferences and to be innovative in the provision of policies and public services, the greater the potential for economic efficiency and growth. There is, however, little empirical evidence to substantiate this claim. In this paper we examine, using a panel data approach with dynamic effects, the relationship between the level of fiscal decentralization and economic growth rates across 16 Central and Eastern European countries over the 1990–2004 period. Our findings suggest that, contrary to the majority view, there is a significant negative relationship between two out of three fiscal decentralization indicators included in the analysis and economic growth. However, the use of different time lags allows us to nuance this negative view and show that long‐term effects vary depending on the type of decentralization undertaken in each of the countries considered. While expenditure at and transfers to sub‐national tiers of government are negatively correlated with economic growth, taxes assigned at the sub‐national level evolve from having a significantly negative to a significantly positive correlation with the national growth rate. This supports the view that sub‐national governments with their own revenue source respond better to local demands and promote greater economic efficiency  相似文献   

4.
Policy makers and academics frequently emphasize a positive link between city size and economic growth. The empirical literature on the relationship, however, is scarce and uses rough indicators for the size of a country's cities, while ignoring factors that are increasingly considered to shape this relationship. In this paper, we employ a panel of 113 countries between 1980 and 2010 to explore whether 1) there are certain city sizes that are growth enhancing and 2) how additional factors highlighted in the literature impact the city size/growth relationship. The results suggest a nonlinear relationship which is dependent on the country's size. In contrast to the prevailing view that large cities are growth‐inducing, for a majority of countries relatively small cities of up to 3 million inhabitants are more conducive to economic growth. A large share of the urban population in cities of more than 10 million inhabitants is only growth promoting in countries with an urban population of 28.5 million and more. In addition, the relationship is highly context‐dependent: a high share of industries that benefit from agglomeration economies, a well‐developed urban infrastructure, and an adequate level of governance effectiveness allow countries to take advantage of agglomeration benefits from larger cities.  相似文献   

5.
A. Riaz    G. Li    Z. Quresh    M. S. Swati  C. F. Quiros 《Plant Breeding》2001,120(5):411-415
Significant heterosis for seed yield in oilseed rape has created interest in the development of hybrid cultivars. The DNA‐based marker protocol, sequence‐related amplified polymorphism (SRAP) was used to determine genetic diversity among oilseed rape maintainer and restorer lines. This measure was used in an attempt to establish an association between genetic distance and heterosis in hybrids for various agronomic traits. A total of 118 polymorphic loci were generated by 18 SRAP primer combinations. Based on the polymorphism generated by the markers, calculated similarity index values ranged from 0.46 to 0.97. Cluster analysis grouped 10 maintainer and 12 restorer lines into three groups, with the exception of two maintainer lines, PM5 and PM9, which fell outside these groups. The grouping of the lines was largely in agreement with the available pedigree data on their origin and agronomic performance. Analysis of variance among inbred lines and their resulting F1 hybrids over two locations revealed significant differences for plant height, days to maturity and seed yield, but not for oil content. Substantial mid‐parent heterosis was observed only for seed yield, and ranged from 26% to 169%. All hybrids surpassed their respective inbred lines for this trait, except for a single cross combination of related lines. In general, crosses of lines located in different clusters yielded more than those from the same clusters. Regression analysis revealed a statistically significant relationship between the genetic distance of the parents and seed yield in their hybrid, and their derived mid‐parent and high‐parent heterosis. The correlation coefficient between genetic distance and yield (0.64) indicated a moderately strong relationship, so it is possible that some of the SRAP markers might be linked to quantitative trait loci for seed yield.  相似文献   

6.
Differences in agglomeration externalities and industrial regimes between locations generate performance differentials for their localized economic activities. For more than two decades, scholars have debated which externality is dominant for growth and under which regime. This study aims to resolve this debate by analyzing the influence of agglomeration economies on the growth of five‐digit manufacturing sectors and firms for Indonesian cities and regencies between 2000 and 2009. This is investigated employing the recent reconceptualization of variety based on sectoral linkages distinguishing related and unrelated varieties, which allow assessing their idiosyncratic economic roles. The findings support that economic relatedness is the dominant source for expansion of sectors and firms within Indonesian locations. Specialized clusters and competition are inversely related to manufacturing growth, although the latter fosters sectoral employment within Indonesian regencies. Population density and human capital show antithetic effects between cities and regencies due to their distinctive urbanization trajectories and industrial compositions.  相似文献   

7.
Cashew (Anacardium occidentale) is a widespread tropical tree crop that is grown primarily for its nuts and has a global production of over 2 million Mt. In spite of its economic importance to many countries, however, no linkage map containing STS anchor sites has yet been produced for this species. This is largely attributable to a prolonged juvenile phase of the tree (limiting mapping to F1 progenies) and difficulty in effecting sufficient hand-pollinations to create mapping populations of effective size. Here, we produce an F1 mapping population of 85 individuals from a cross between CP 1001 (dwarf commercial clone) and CP 96 (giant genotype), and use it to generate two linkage genetic maps comprising of 205 genetic markers (194 AFLP and 11 SSR markers). The female map (CP 1001) contains 122 markers over 19 linkage groups and the male map (CP 96) comprises 120 markers assembled over 23 linkage groups. The total map distance of the female map is 1050.7 cM representing around 68% genome coverage, whereas the male map spans 944.7 cM (64% coverage). The average map distance between markers is 8.6 cM in the female map and 7.9 cM in the male map. Homology between the two maps was established between 13 linkage groups of the female map and 14 of the male map using 46 bridging markers that include 11 SSR markers. These maps represent a platform from which to identify loci controlling economically important traits in this crop.  相似文献   

8.
ABSTRACT The tendency of firms to cluster within a region has been observed for quite some time. However, it is only over the past two decades that business researchers have focused much attention on clusters, particularly in terms of their entrepreneurial and innovative characteristics and potential. At the same time, regional developers around the world have put much effort in promoting the formation of clusters. A gap in such efforts is an understanding of the differences among types of clusters. This article draws a distinction between two generic types of clusters: technology‐based and industry‐focused. Using the resource‐based view as the organizing framework, we argue that the two generic cluster types create very different regional resource profiles over time, accumulating resources in a different manner, cultivating different capabilities, and deriving different sources of regional advantage. As concluded in the study, these differences are likely to have implications for firms located in the regions as well as for economic developers and public policy officials charged with developing cluster strategies.  相似文献   

9.
利用22个表型性状和60个微卫星(simple sequence repeat, SSR)位点对黑龙江省140份代表性种质(78份地方品种和62份育成品种)进行分析, 根据UPGMA (unweighted pair group method with arithmetic mean)和Model-base对SSR数据进行遗传结构划分。结果表明, 参试品种可分为2大类群, 第II类群的各项多样性指标均高于第I类群, 2个类群遗传距离为0.2427;PCO结果显示这2个类群分布在不同区域, 这与地理来源和育成年代密切有关。依据品种类型分为育成品种和地方品种两组, 后者的各项多样性指标均高于前者, 两组间的遗传距离为0.1131。依据表型数据的PCO分析表明, 分布区域与品种类型有关, 与SSR结构分类的结果吻合度低, 两组品种主要在3个主成分的6个表型性状上有所不同。它们不是2个相对独立的遗传群体, 根据分子标记和表型分类各有特点;建议在种质遗传多样性研究中将分子数据和表型数据结合起来。  相似文献   

10.
Abstract: Through reviewing South‐East Asia’s recent economic engagement with the global economy, this paper points to profound recent transformations in the scope and character of the region’s development. Foreign direct investment was the key driver of regional growth in the pre‐1997 period, yet currently, the region faces a more difficult and multifaceted economic arena from which to attract such funds. Foreign direct investment is more selective, both geographically and by sector, than was the case in that earlier period. This paper explains the confluence of economics, business practices and politics that are giving rise to these outcomes, and concludes from this that development trajectories in South‐East Asia will become more diverse between the countries of the region, with implications for how we understand regional economic performance.  相似文献   

11.
The genetic diversity of Patellifolia patellaris has been investigated to generate information required for the organisation of a systematic genetic resources conservation action combining the best elements of the ex situ and in situ conservation concept. To this end, ten occurrences of the species were sampled on the Iberian Peninsula in Portugal and Spain. A total of 271 individuals was analysed using 24 microsatellite markers. The factorial analysis separated the material into two occurrences from Portugal, two occurrences sampled east of Gibraltar and six occurrences from the eastern Spanish coast. The pairwise genetic distance between occurrences and the complementary compositional differentiation among occurrences were calculated. The genetic distance values were used to construct an Unweighted Pair Group Method with Arithmetic Mean tree, which can be separated into four equidistant clusters. Two clusters are located in Portugal and two further clusters in Spain. The factorial analysis as well as the genetic distance and differentiation analysis indicate that the two occurrences from Portugal are clearly genetically different from the Spanish group of occurrences. Both occurrences have low population sizes and are therefore highly endangered. In situ conservation actions are urgently required for both occurrences. Further investigations are needed to organise better informed conservation actions for P. patellaris, namely to study genetic relationships between occurrences on the Spanish mainland and occurrences distributed on the Canary Islands, Madeira and Cape Verde Islands as well as in Morocco.  相似文献   

12.
S. Tavoletti    L. Iommarini 《Plant Breeding》2007,126(6):607-611
Levels of genetic similarity characterizing 20 grasspea (Lathyrus sativus L.) populations collected in central Italy (17 populations in the Marche region and three populations in the Abruzzo region) were analysed with amplified fragment length polymorphism (AFLP) molecular markers. Two main clusters were found: one included large‐seeded populations from farms that were not market‐oriented (named Household populations) and the second, small‐seeded populations, cultivated in market‐oriented farms (named Commercial populations). Relationships among populations collected in different regions were found, although one population of the Abruzzo region was placed between the two main clusters, suggesting a possible further genetic differentiation within this grasspea germplasm collection. Principal component analysis based on AFLP marker frequency was effective in identifying polymorphic markers showing high discriminating ability between clusters H and C. In particular, seven markers showing high positive and three markers with low negative PC1 scores showed an almost cluster‐specific distribution. These results will be useful for enhancing Italian grasspea germplasm use in plant‐breeding programmes and for extending grasspea cultivation within the sustainable agricultural systems of central Italy.  相似文献   

13.
Y. D. Kim    J. Y. Min    C. S. Karigar    G. W. Cheong    J. W. Kim    M. S. Choi 《Plant Breeding》2007,126(6):634-637
A simple and rapid colorimetric method for the determination of caffeine has been developed. Tea tree lines from the Hadong region in South Korea differ widely in their caffeine contents and this colorimetric method facilitated an efficient screening strategy for the selection of low‐caffeine‐containing lines. A high correlation was observed between the values obtained with colorimetric and high‐performance liquid chromatographic analysis. Among the selected tree lines, the caffeine content for the lowest caffeine‐containing tea tree line (H‐19) was 178.35 μg/g dry weight basis, which was 61‐fold less productive than the highest caffeine‐producing tea tree line (H‐82). Caffeine contents of the selected tea tree lines remained similar during the corresponding collection periods. The colorimetric method is of great practical value in screening low‐caffeine‐containing tea trees.  相似文献   

14.
Using the PUMS files of the 2000 U.S. Census and 2005–2007 merged ACS data, we study the metropolitan destination choices made by newly arrived immigrants from seven top source countries between 2000 and 2007. Using a multinomial logit model, we find that the dispersion of new immigrant groups varies by origin, although all groups were subject to 1) the attraction of co‐ethnic communities, and 2) the positive effects of labor market conditions in the destination (especially the employment growth rate). However, co‐ethnic concentration is much more important than labor market conditions in the destination choice decision, particularly for the poorly educated. Conversely, there is a strong negative effect of co‐ethnic concentration on highly educated new immigrants, revealing a dispersed geographical pattern of these highly educated immigrants. We also find the importance of employment share growth rate for highly educated immigrants which suggests that they are more sensitive to the upward employment structure at the destination than a specific job growth rate, and they may not be attracted by a metropolitan area with a low‐quality employment structure, despite whether there was an increase in high‐level jobs.  相似文献   

15.
ABSTRACT Cross‐country studies of education and economic prosperity often reach conflicting results when using growth rates as the measure of economic development. However, growth rates lack persistence over time and may not accurately measure long‐term economic success over relatively short economic horizons. To overcome this potential specification problem, we estimate the relationship between key education variables and the capital to physical labor ratio. Using both cross‐sectional and panel specifications, we find that both the primary‐pupil–teacher ratio and decentralized education finance are associated with a larger capital to physical labor ratio. The relationship between human capital and expenditures, private education, and test scores are less robust.  相似文献   

16.
B. A. Kiula    N. G. Lyimo    A.-M. Botha 《Plant Breeding》2008,127(2):140-144
Identifying the best inbred combinations for the development of commercial hybrid maize varieties remains the main challenge to maize breeders. The aim of this work was to study associations between the genetic distance (GD) of 21 inbreds and the corresponding F1 phenotypic data. Furthermore, the impact of grouping lines into genetically similar clusters was investigated. The 21 inbred lines were fingerprinted using amplified fragment length polymorphism markers. Parents and 210 F1 progeny were evaluated in the field. Joint data analysis mostly revealed a tighter association between GD and the F1 performance or mid parent heterosis in the intergroup than in the intragroup crosses. Despite these correlations, intergoup crosses should always be field‐tested before their release. Crosses showing low GD values should be discarded to avoid field‐testing costs. Better F1 hybrid performance predictions can be achieved by integrating molecular and F1 phenotypic data.  相似文献   

17.
ABSTRACT The spatial extension of production networks presents a significant challenge to managers accustomed to reducing lead times by geographically contracting supply chains. This paper extends the theory on time in transportation by defining the elements of transport time, order time, timing, punctuality, and frequency and elaborating on their characteristics. Structured along these elements, it analyses the consequences of extending production networks from within a mature economic region, mainly the EU‐15, U.S., and Japan, first to adjacent and then to nearby and finally distant low‐cost regions. Distance obviously affects the transport quality in all time dimensions. Except for air parcel services that globally match what road transport offers within an economic region, the longer the distance, the lower the time‐related performance. Distant, low‐cost regions, meaning China and India, also imply a polarisation between air and sea transport at opposite ends of the time, cost, and capacity scales. This supply gap restricts the types of products traded. The conceptual framework is illustrated in the setting of a global vehicle manufacturer spatially extending its sourcing. It demands that sequenced sub‐assemblies and small, cheap, and generic components are delivered from the vicinity of each assembly plant. Batched components can be sourced from adjacent regions, but deliveries from longer distances imply storage at pick‐up points to fulfil their time requirements. Hence, the suppliers must offer the manufacturing firm deliveries as if they produce relatively close to the assembly plants.  相似文献   

18.
The relationship between commuting distances and where people work has been studied for urban contexts in both developed countries and developing countries. However, few studies have examined the situation in rural areas, and none look at commuting distances to non‐farm workplaces in rural areas of developing countries. This paper investigates how commuting distance, and thus accessibility, to local non‐farm work influences non‐farm employment and out‐migration from rural villages in Northeast Thailand. The main issues examined are: (i) the distance that rural residents travel to work in local non‐farm jobs; and (ii) the influence that local non‐farm employment has on the number of outmigrants from rural villages. The study finds: (i) distance between villages and non‐farm work sites impact the number of villagers who are employed in regular wage work; (ii) beyond 20 km villagers are less likely to travel to non‐farm employment using their own means of transportation; and (iii) employment in regular wage work decreases outmigration. The findings from this study contribute to the debates over the drivers of rural out‐migration, rural livelihood changes, and agrarian changes that are taking place in Southeast Asia.  相似文献   

19.
The aim of this study is to empirically examine regional resilience by assessing economic growth patterns in two distinct groups of regions across the European Union in the aftermath of the 2008 economic and financial crisis. In an effort to consider the regions as interconnected economic areas and account for spillover effects, the model incorporates complex spatial effects that consider both spatial heterogeneity and spatial dependence. The analysis follows a step‐wise approach. First, spatial heterogeneity is assessed by employing Exploratory Spatial Data Analysis, which identifies two distinct spatial regimes, a core and a periphery, based on their initial level of economic development. A Spatial Durbin Model is then employed to estimate the determinants of regional resilience and growth in both regimes, including potential spillover effects. Results indicate that while both spatial regimes experience processes of economic convergence, recent determinants of growth, as well as spillover dynamics, differ across the two. In the core regime, better institutions, higher shares of investment, and an economy specialized in higher value‐added sectors significantly spur domestic growth, with investment also inducing positive spillover effects to neighbouring regions. In the peripheral regime, low shares of lower‐secondary educational attainment and high shares of tertiary educational attainment have a significant positive effect on domestic growth, with higher shares of tertiary educational attainment also inducing positive spillover effects. Moreover, technological readiness is also identified as an important factor in the peripheral regime with positive spillover effects. Upon the bedrock of these findings, initial policy proposals are offered.  相似文献   

20.
The use of gliadins in cultivar identification is a well‐known practice that is used in many countries. The aim of this study was to determine the gliadin banding patterns of 35 commercial South African wheat cultivars and to use these data to determine genetic relationships between the cultivars using sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. The index of genetic similarity was used to calculate pairwise distance matrices, which were converted to a dendogram. Most of the gliadin bands fell within the nomenclature used. Fourteen cultivars had one novel band and six had two novel bands. All the cultivars could be distinguished from one another. Genetic distances between clusters were small. This suggested that there was not enough unique genetic variability to set any cluster apart from the others.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号