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141.
Chuan-Zhong Li Karl-Gustaf Löfgren Martin L. Weitzman 《Environmental and Resource Economics》2001,18(4):355-366
The point of departure for this paper is the familiar prototype fisheriesmodel where a fictitious sole owner harvests a fish population to maximizepresent discounted profits. The paper answers analytically the followingquestion. ``What happens to a policy when the sole owner also valuesbiodiversity, as well as profits?'' It turns out that the size of the steady-state stock and the number of species preserved are both higher, whenspecies diversity is positively valued. This paper provides a sharpcharacterization of the optimal policy in terms of the usual economicparameters and an exogenously introduced willingness-to-pay function forspecies preservation. 相似文献
142.
In this study, a price prediction model for futures markets of crypto assets is presented. Random Forest was used to study three scenarios as a function of input variables: technical indicators, candlestick patterns and both simultaneously. In turn, the model parameters, the time intervals, and the most suitable investment horizons were studied. In addition to showing the results from the model, a one-year out-of-sample prediction was simulated. The entire year of 2020 was chosen because the three possible stock market scenarios occurred in this year: a sideways market, a bear market resulting from the global pandemic and an end-of-year bull market. Last, this out-of-sample simulation was analyzed as a real operation, that is, by retraining the model after each new collection of data, so that the model had the maximum information at all times. In conclusion, using candlestick patterns instead of technical indicators, improves the efficiency of the results. 相似文献
143.
We present the results of two efficiency measures that include intraday return predictability measure based on order imbalance and measures of several variance ratio tests on intraday subsamples of nine major Indian agricultural commodity futures (castor seed, cotton oil cake, rape mustard seed, soybean, refined soya oil, crude palm oil, jeera, chana, and turmeric) quoted in the National Commodity and Derivatives Exchange (NCDEX). We perform the efficiency measures on five subsamples with holding periods of 5, 10, 15, 30, and 60 min over two sample periods following the announcement of the merger between the Forward Market Commission (FMC) and Securities Exchange Board of India (SEBI). We compare results of tests of weak-form market efficiency of futures markets between two periods (pre-merger period and post-merger period). Our results confirm that Indian agricultural commodity futures markets continue to remain inefficient in the short-term during both pre-merger and post-merger periods. Based on these findings, it is likely that profitable trading strategies in the short intraday intervals will be available for traders and market participants during post-merger period. Thus, regulators must focus more on policy initiative so as to enhance market quality in order to address such inefficiencies in Indian commodity futures markets. 相似文献
144.
地方高校与区域创新系统的协调度研究——对河北省和山西省的实证分析 总被引：1，自引：0，他引：1
地方高校作为区域内的主要知识创新源,对区域创新系统的发展,创新绩效的提高有重要的促进作用。地方高校系统作为区域内的一个子系统与区域创新系统相互关联、相互促进,共同构成了一个相互协同的复合系统。文章利用协同学理论的分析框架,从地方高校系统和区域创新系统两方面选取指标作为模型序参量,并引入地方高校系统和区域创新系统协同发展的协调度模型,对河北省和山西省两个区域的地方高校与区域创新系统的协调发展进行了比较分析,并得出了有益的结论。 相似文献
145.
We consider the problem of randomly assigning n indivisible objects to n agents. Recent research introduced a promising mechanism, the probabilistic serial that has superior efficiency properties than the most common real-life mechanism random priority. On the other hand, mechanisms based on Gale's celebrated top trading cycles method have long dominated the indivisible goods literature (with the exception of the present context) thanks to their outstanding efficiency features. We present an equivalence result between the three kinds of mechanisms, that may help better understand why efficiency differences among popular mechanisms might arise in random environments. This result also suggests that the probabilistic serial and the random priority mechanisms can be viewed as two top trading cycles based mechanisms that essentially differ in the initial conditions of the market before trading starts. 相似文献
146.
Tea expansion, a typical process of regional land use and cover change (LUCC), has raised great concerns on regional sustainability. In this regard, exploring the determinants of tea expansion should provide critical implications for land use policy. It has been widely recognized that LUCC interacts nonlinearly with a set of determinants and their feedbacks should be rather complex. Policy makers are now facing the challenge to identify, apportion, and compare the determinants of regional tea expansion for designing more targeted political intervenes. Our paper utilizes a robust tool, the random forest (RF) regression in particular, to explore the determinants of tea expansion across two periods (1985–2007 and 2007–2016) in Anji County, a typical region of tea production in subtropical China. More specifically, tea is extracted from Landsat imageries and total tea cultivated area acts as the dependent variable. Exploratory variables include 38 potential determinants and these determinants are divided into two categories (biophysical and socioeconomic) at two levels (pixel and village). We obtain some similar findings, though the relative importance of determinants varies with the two periods. In general, biophysical determinants (e.g., topography, soil type, land use in the neighborhood) present greater relative importance than the socioeconomic determinants in both periods. In period 1985–2007, biophysical determinants at pixel level are more essential in governing tea expansion. In period 2007–2016, the relative importance of pixel level biophysical determinants is comparable with that of the village level determinants. Comparisons of the two periods indicate that relative importance of soil type and socioeconomic proximity becomes greater in period 2007–2016, while that of the total employees and non-agricultural population proportion becomes lower. Partial dependency plots are further drawn to visualize the marginal effect of each determinant. We finally propose three options for land use policy towards sustainability. Our study demonstrates that the RF regression is efficient for policy makers to understand the determinants of tea expansion with a nonlinear and complex nature. 相似文献
147.
Charles Waterfield 《Food Policy》1985,10(4):337-351
This article is concerned with a new nutritional intervention strategy, which is based on the belief that malnourished people eat different types of food to the well-nourished. The calculation of disaggregated food consumption parameters can identify ‘inferior’ food commodities; and the subsidization of these commodities will target intervention to those most in need. The effectiveness of this policy depends on the understanding of its theoretical basis. The author introduces the policy maker to this by reviewing the theoretical basis for consumption analysis, and then several key studies. 相似文献
148.
利用电子表格和Section软件,提出了非稳定流抽水试验资料分析的一种新方法。该方法首先利用电子表格对数据进行处理,然后在Section软件中进行投影,并把实测点和理论曲线进行拟合,求出相应的水文地质参数。达到了省时、省力、减少误差的目的。 相似文献
149.
《Food Policy》2013
Price transmission models are estimated using recursive methods across 100 food commodities. From the individual commodities, short- and long-run price transmission coefficients are estimated for rising and falling prices. These coefficients are classified into five commodity categories and expressed as one vector while coding for causality, market levels, rising/falling prices, short and long run, and time period. Then the impact of each variable is estimated and inferences are drawn about the degree of price transmission. Results show that price linkages are strong but slightly declining over time, with some evidence of asymmetric behavior. Long-run rising prices are passed through more than long-run falling prices, except for fruits and vegetables. 相似文献
150.
介绍了如何对紫金Ⅱ微机进行改进,使其既保持原有的性能(用高级语言编程)又具有单片机的工控特性。举出了用于控制通风管道温度参数的成功例子。 相似文献