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71.
We present a model of optimal flow pollution control considering explicitly the dynamics of the corresponding assimilative capacity. We focus first on the degradation of this assimilative capacity triggered by pollution excesses and determine the intertemporal efficient pollution path, taking into account this ecological feedback. Our analysis shows that a minimum level of initial assimilative capacity is necessary to prevent its optimal extinction. We then allow for the restoration of assimilative capacity and characterize the conditions under which this option frees the optimal policy from the dependency on the initial conditions. In both cases our results call for environmental standards based on the shadow price of assimilative capacity that are stricter than the static optimum commonly used in flow pollution control.  相似文献   
72.
The farm size and productivity debate has been limited by the focus on land or labor productivity, generally showing respective productivity advantages to smaller or larger sized farms. Our purpose is to provide new perspectives on the debate by bringing together evidence from a set of novel case studies in both rich and poor countries. Common to them are the adoption of total factor productivity (TFP) as the comparative performance measure, and the reliance on panels of farm micro data. The present article presents a synthesis of findings from five case studies in (i) Malawi, Tanzania, and Uganda; (ii) Bangladesh; (iii) Brazil; (iv) Australia; and (v) the United States. The preponderance of evidence from these studies suggests that there is no single economically optimal agrarian structure; rather, it appears to evolve with the stage of economic development. Certain farm sizes face relative productivity advantages, such as small farms in Africa. But with economic and market growth, that smallholder advantage will likely attenuate, moving toward constant and eventually increasing returns to size. Yet, importantly, small farms may be quite dynamic, and need not be a drag on agricultural growth until perhaps well into the development process.  相似文献   
73.
We derive and estimate a model of demand for Geographical Indications allowing for subjective and heterogeneous quality perceptions, and study vertical differentiation based on multi-tier quality labels within the context of the strategy adopted by the Chianti Consortium. Quality perceptions and wine choices are elicited in an online experiment where the number of quality tiers is augmented incrementally in a between-subject design. The empirical model includes subjective quality perceptions as an (endogenous) explanatory variable, and unexplained heterogeneity in WTP for quality as a random parameter. We find that quality perceptions are endogenous to the labeling regime, and adding a high-quality label (Chianti Classico Gran Selezione) decreases the perceived quality of all other Chianti wines, but not the competitor wines. However, the market shared lost to perception restructuring is small compared to the benefits of increased vertical differentiation.  相似文献   
74.
This study investigates whether major USDA reports still provide important news to changing crop markets. The news component of each report, or market “surprise,” is measured as a difference between the USDA estimate and its private expectation in corn, soybeans, and wheat markets. Changes in the relevance of USDA information are assessed by examining changes in the magnitude of market surprises and shifts in the futures price reaction to these surprises, which isolates the impact of each report. The stable size of market surprises over time suggests that competition from alternative data sources has not reduced the news component of USDA crop reports. Increasing price reaction to most reports, including those facing competition from alternative information sources, suggests that value of public information may be enhanced in uncertain markets affected by structural changes.  相似文献   
75.
Food safety is a very important topic in China. We investigate Chinese consumers’ preferences and willingness to pay (WTP) for food traceability using a choice experiment. Given that consumers’ trust in the food system may affect their preferences and WTP, we also assess the interaction between consumers’ trust in government’s supervision of food safety and food labels and consumers’ preferences for traceable food products. Using data collected from a choice experiment on Fuji apples in a face-to-face survey in six Chinese cities, the results show that (i) consumers are willing to pay for traceable food but their valuations can differ upon the degree of their trust in government’s supervision of food safety and food labels; (ii) consumers are willing to pay for traceability with strong evidence of preference heterogeneity; (iii) government is not the most trusted safety inspection and certificate authority as found in prior studies using animal food products in China.  相似文献   
76.
This article provides evidence on the role of consumer food subsidies in improving nutritional intake and diet quality by evaluating the expansion of the government food assistance program coverage in the hunger prone state of Odisha in India. In 8 districts of Odisha, popularly known as the Kalahandi-Balangir-Koraput (KBK) region which is notable for extreme poverty and starvation deaths, the government did away with the targeted food assistance program in 2008 and made the scheme universal. Using a Difference-in-Difference methodology over two repeated cross sectional household surveys, this article finds that the shift from targeted to a universal food security program in the KBK region of Odisha has led to an improvement in the household nutritional intake and diet quality. Further examination suggests that proportion of households consuming below the recommended dietary allowance of calorie, fats and protein has declined significantly in this region post the intervention.  相似文献   
77.
To lead the world's fifth-generation mobile communication networks (5G) market, China introduced several policies to support 5G industry development that will impact telecommunication operators, the main implementers in this industry. Thus, this study examines the impact of the government's 5G policy announcements on telecommunication operators' firm value in China, where the state exerts a strong influence on industry development. We find that government policy announcement in general affects telecommunication operators' stock returns negatively, and when the government announces policies with a higher level of interference, the decline in firm value is more pronounced. To understand the comprehensive impact of 5G technology on telecommunication operators, we also examine the effect of institution-driven corporate technology R&D and investment activities on firm value. We find that the firms' 5G activities also decrease their firm value, and this effect is more significant than government policy announcements. These results imply that the market has a negative evaluation of the introduction of 5G technology due to its immaturity and uncertainty. This study provides a basis for understanding the market's views on 5G technology and development policies.  相似文献   
78.
Future 5G networks aim at providing new high-quality wireless services to meet stringent and case-specific needs of various vertical sectors beyond traditional mobile broadband offerings. 5G is expected to disrupt the mobile communication business ecosystem and open the market to drastically new sharing based network operational models. 5G technical features of network slicing and small cell deployments in higher carrier frequencies will lower the investment barrier for new entrants to deploy local radio access networks and offer vertical specific services in specific areas and allow them lease the remaining required infrastructure on demand from mobile network operators (MNO) or infrastructure vendors. To realize the full vision of 5G to benefit the society and promote competition, innovation and emergence of new services when the 5G end-to-end network spans across different stakeholders administrative domains, the existing regulations governing the mobile communication business ecosystem are being refined. This paper provides a tutorial overview on how 5G innovations impact mobile communications and reviews the regulatory elements relevant to 5G development for locally deployed networks. This paper expands the recent micro licensing model for local spectrum authorization in future 5G systems and provides guidelines for the development of the key micro licensing elements. This local micro licensing model can open the mobile market by allowing different stakeholders to deploy local small cell networks with locally issued spectrum licenses ensuring pre-defined quality guarantees for the vertical sectors’ case specific needs.  相似文献   
79.
In this paper we analyze high-frequency movements in Swiss asset markets in reaction to real-time communication by the Swiss National Bank. Our analysis of central bank communication encompasses monetary policy announcements, speeches and interviews. We examine the reactions of the currency market, the bond market and the stock exchange. The evidence suggests that speeches and interviews, along with monetary policy announcements, engender a significant price reaction. This paper sheds light on the relevance of communications other than monetary policy announcements.  相似文献   
80.
In this paper, we develop a continuous time factor model of commodity prices that allows for higher-order autoregressive and moving average components. We document the need for these components by analyzing the convenience yield’s time series dynamics. The model we propose is analytically tractable and allows us to derive closed-form pricing formulas for futures and options. Empirically, we estimate a parsimonious version of the general model for the crude oil futures market and demonstrate the model’s superior performance in pricing nearby futures contracts in- and out-of-sample. Most notably, the model substantially improves the pricing of long-horizon contracts with information from the short end of the futures curve.  相似文献   
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