A line-of-sight optimised MIMO architecture for outdoor environments

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A General Algorithm for Simultaneous Estimation of Constant and Randomly-Varying Parameters in Lineal Relations

A recursive algorithm for estimating linear models with both constant and time-varying parameters is derived by maximization of a likelihood function. Recursive formulas are also derived for derivatives of the likelihood function; the derivatives are needed for numerical evaluation of some parameters. Smoothing formulas are also derived. The estimation algorithm is compared with others for similar classes of models.

The performance of Bulgarian food markets during reform

Food policy often depends on markets and markets depend on institutions. But how good do institutions have to be before reforms can be launched? Relying on well timed surveys of agricultural prices and a joint study by the Government of Bulgaria and the World Bank on agricultural market institutions, this paper presents evidence that performance in food markets improved following significant policy reforms in Bulgaria, although public institutions remained weak. This suggests that even though strong institutions are preferred to weak ones, it can be costly and impractical to delay policy reforms until work on strengthening institutions is finished. Still, measured performance varied by place and by commodity, suggesting that markets developed at different tempos and that the distribution of benefits from improved markets was uneven. This points to the need to address the costs of adjustment as policies change. The paper introduces a new approach to measure market performance based on composite-error techniques.Markets and Market Access,Transport Economics Policy&Planning,Economic Theory&Research,Access to Markets,Agribusiness

Direct Subsidies and Technical Efficiency in Greek Agriculture

In this paper we apply the technical inefficiency effect model to a set of eight different crop products (i.e., wheat, mixed arable crops, tobacco, cotton, olive oil, fruits, vegetables, and greenhouse horticulture) in Greek agriculture. For each product, a panel data set covering the period 1991-1995 is used and separate econometric results are obtained for each product. A particular set of socioeconomic and demographic variables is used to explain technical efficiency differentials among Greek farmers, including the direct subsidies given to each farmer, and the concordance of these efficiency determinants is discussed across the eight different crop products considered.Direct subsidies, technical efficiency, Greek agriculture, Agricultural Finance,

The Impact of Domestic and International Commodity Price Volatility on Agricultural Income Instability: Ghana, Vietnam and Peru

The extent to which commodity price volatility affects the income of producing households and their vulnerability to poverty and food insecurity depends on household diversification patterns and the degree of their exposure to markets. This article focuses on estimating agricultural income uncertainties for a number of different household types in Ghana, Vietnam and Peru. We develop explicit formulae for household income variance, and we combine information from household datasets and commodity price time-series in order to estimate the income uncertainty that emanates from price and production volatility under different scenarios of exposure to international and domestic markets shocks. Our results indicate that market and nonmarket uncertainties significantly affect the variability of agricultural income of households in these countries, and especially households that are specialized in a few commodities. However, it turns out that, under current policies, almost all of their income variability is due to domestic factors, with international prices not contributing much, at least in the short run. Wider exposure to international markets would increase the income variability of producers who have been subjected to domestic market stabilization policies in Ghana and Vietnam, while it would decrease it in the case of Peru.commodity prices, risk, households