Marshallian Externalities And The Emergence And Spatial Stability Of Technological Enclaves *

Technological dualism often is found to be associated with the geographical clustering of firms that use the same techniques. To shed further light on these localization phenomena, we analyze the long-run dynamic behavior of a system in which firms' choices among alternative production methods (each of which requires a technique-specific input) are influenced by both firm-specific random shocks and Marshallian ‘industrial neighborhood’ effects. The latter are local factor market externalities that tend to lower the relative marginal costs d those inputs that are used most extensively in the immediate locale. The model developed here focuses on labor market externalities affecting the supply conditions for workers with technology-specific skills, and their effect on the choices made by producers at various sites whose choice of technique is subject to periodic revisions. A special structure familiar in the applied theory of Markov random fields, the stochastic Ising model. provides a reduced-form representation of this dynamic spatial system. The general properties of models of this type and their application in economics are considered. Discrete time numerical simulations of the behavior of an ensemble of firms (located at the nodes of a finite lattice formed on a two-dimensional (orus) shows that positive neighborhood externalities effects do not necessarily result in the uniquitous diffusion of one of the two available technologies. Instead. this system exhibits a spatially localized form of ‘technological dualism," in which at least two technological enclaves emerge and undergo path-dependent evolution. The temporal durations of these spatial patterns in technology adoption are affected by parameters of the Ising model that can be given a straightforward economic interpretation     

Longitudinal Poisson Assessment of Factors Influencing Farmers’ Market Counts

ABSTRACT

This study uses secondary longitudinal data and a first difference pooled Poisson regression model to explain annual counts for farmers’ markets in the United States. Data were collected for all 50 states and the District of Columbia for 10 years, from 2004 to 2013, leading to a longitudinal data set with 510 observations. Results indicate that population growth and funds routed toward Women, Infants, and Children (WIC) farmers’ market nutrition programs increase farmers’ markets’ annual counts. The rate ratio of farmers’ markets’ counts for highly populated states that have both WIC and senior farmers’ market nutrition programs is approximately three times greater than their counterparts. Areas with high agriculture output experience a significant increase in counts. States located in the south and in desert areas have lower counts than other regions. This study suggests important recommendations to policy makers, farmers’ market managers, and researchers.     

能源电力院校应用化学专业实践教学体系探索

为了培养应用型化学人才，沈阳工程学院能源电力院校应用化学专业不断探索实践教学体系的改革与发展。建立了“多模块、全程融合”能源电力鲜明特色的多层次实践教学体系，增加以学生就业岗位工作任务为背景的实践内容，将实践能力的培养贯穿于人才培养的全过程。通过长期不懈地努力，在人才培养质量、校外人才培养基地建设、学生综合实践能力等方面取得了显著成效，为培养具有综合实践能力的应用型化学专业人才奠定基础。     

Kinderfreibeträge in der gesetzlichen Rentenversicherung

The future of the German pay as you go public pension system is dependent on families with children. In contrast to German tax law, there are no child allowances in the social insurance system. As a result, workers with and without children pay the same pension insurance contributions. This article analyses the introduction of a child allowance into the public pension system in Germany. We quantify the fiscal, distributional and behavioural effects of such a reform.     

Why do global long‐term scenarios for agriculture differ? An overview of the AgMIP Global Economic Model Intercomparison

Recent studies assessing plausible futures for agricultural markets and global food security have had contradictory outcomes. To advance our understanding of the sources of the differences, 10 global economic models that produce long‐term scenarios were asked to compare a reference scenario with alternate socioeconomic, climate change, and bioenergy scenarios using a common set of key drivers. Several key conclusions emerge from this exercise: First, for a comparison of scenario results to be meaningful, a careful analysis of the interpretation of the relevant model variables is essential. For instance, the use of “real world commodity prices” differs widely across models, and comparing the prices without accounting for their different meanings can lead to misleading results. Second, results suggest that, once some key assumptions are harmonized, the variability in general trends across models declines but remains important. For example, given the common assumptions of the reference scenario, models show average annual rates of changes of real global producer prices for agricultural products on average ranging between ?0.4% and +0.7% between the 2005 base year and 2050. This compares to an average decline of real agricultural prices of 4% p.a. between the 1960s and the 2000s. Several other common trends are shown, for example, relating to key global growth areas for agricultural production and consumption. Third, differences in basic model parameters such as income and price elasticities, sometimes hidden in the way market behavior is modeled, result in significant differences in the details. Fourth, the analysis shows that agro‐economic modelers aiming to inform the agricultural and development policy debate require better data and analysis on both economic behavior and biophysical drivers. More interdisciplinary modeling efforts are required to cross‐fertilize analyses at different scales.     

The trade and environment nexus in Mexican agriculture. A general equilibrium analysis

This paper analyzes linkages between growth, trade and the environment in Mexican agriculture with an empirical economy-wide model. The investigation considers trade liberalization, environmental policy reform, and their coordination. The analysis decomposes the change in pollution emission induced by changes in the sectoral composition of production, effects of technology on emission intensity, and aggregate Scale effects. Outward orientation alone induces a contraction of aggregate agricultural output, but promotes growth and pollution in some agricultural sectors. Overall, free trade does not induce wholesale specialization in dirty agricultural activities. Environmental taxes on pollution emitted in agricultural sectors have a moderate negative impact on agricultural output, except for the tax on water-borne toxic chemicals. More liberal trade combined with targeted effluent taxes can achieve significant environmental mitigation and efficiency gains, but with the implication of a contraction of most agricultural sectors.     

Landscapes and territory-specific economic bases

The objective of this paper is to assess the potential of the landscape as a factor for regional development. Using the economic base theoretical framework, economic sectors are differentiated according to their alleged sensitivity to amenities. The empirical analysis clusters French counties on the basis of landscape physical attributes and economic sectors, then estimates the amenity-related basic employment multiplier in three study areas located in the Auvergne and Rhône-Alpes regions. Results tend to show that spending behavior is related to landscape type.     

A cross-section analysis of household demand for food and nutrients in Tanzania

Undernutrition and malnutrition are still problems of unacceptable proportions in many developing countries. However, the debate on the roles of income and other socio-economic variables such as women’s education and household size on food and nutrient demand continues. This study examines the demand for food and nutrients amongst households in Tanzania, using recent survey data. A quadratic almost ideal demand system (QUAIDS) is employed to estimate price and expenditure elasticities, as well as the impact of socio-economic variables on food demand patterns. A moment-based instrumental variable approach is then used to analyse the determinants of nutrient demand. The results show that income and other socio-economic variables exert significant effects on the demand for food and nutrients. The estimated expenditure elasticities for the nutrients range from 0.307 for iron to 1.26 for Vitamin B₁₂. The elasticities are higher for those micronutrients that are consumed through animal products and lower for those micronutrients that are mainly obtained through staple foods. These results reflect the higher expenditure elasticities for meat, fish, eggs, milk, and milk products, as well as fruits and vegetables, relative to cereals and pulses, reinforcing the assertion that the demand for Vitamins A and B₁₂, as well as calcium and zinc will increase with rising income.