Global trends in risk management support of agriculture

The aim of this paper is to make an international comparison of risk management policies in OECD countries as well as in selected emerging economies. The results are based on the data from OECD Producer Support Estimates Database and General Services Support Estimates Database, a study of agricultural insurance schemes carried out by the European Commission and an overview of risk-related policy measures formulated by the OECD. The results indicate that all OECD countries have the price stabilizing support for at least some commodities. Although the share of market price support in the producer support estimates has been decreasing for a long time, it still remains an important component in most countries around the world. The analysis also revealed the pilot experiences with index based insurance in developing countries whose economy is considerably dependent on agriculture.Agriculture, agricultural policy, risk management, market price support, income stabilization, Community/Rural/Urban Development, Environmental Economics and Policy, Financial Economics, International Relations/Trade, GA, IN,

Weather derivative design in agriculture – a case study of barley in the Southern Moravia Region

The aim of this paper is to point out some problems of index estimation for the purposes of weather derivative valuation considering the particularities of agriculture. The assessment of the sensitivity of barley to weather over 40 years has been the basis for the design and valuation of weather derivative in the Czech Republic (The Southern Moravia Region). The analysis is based on regression modeling using temperature index and barley yield. The burn analysis based on parametric bootstrap is used as the method for the valuation of weather derivative contract. With the effective bootstrap tool, the burn analysis may easily be processed and the uncertainty about the pay-off, option price and statistics of probability distribution of revenues can be effectively determined. Nevertheless, the results of the analysis reveal a significant adverse impact of basis risk on the quality of agricultural weather derivative in the Czech growing conditions. The article outlines the scope for use of weather derivative as the reinsurance tool in regions with frequent occurrence of systematic weather risk.Weather derivative valuation, agriculture, risk management, basis risk, burn analysis, Agricultural and Food Policy, Research Methods/ Statistical Methods, Risk and Uncertainty, GA, IN,

Density and current response functions in strongly disordered electron systems: Diffusion, electrical conductivity and Einstein relation

We study consequences of gauge invariance and charge conservation of an electron gas in a strong random potential perturbed by a weak electromagnetic field. We use quantum equations of motion and Ward identities for one- and two-particle averaged Green functions to establish exact relations between density and current response functions. In particular we find precise conditions under which we can extract the current-current correlation function from the density-density correlation function and vice versa. We use these results in two different ways to extend validity of a formula associating the density response function with the electrical conductivity from semiclassical equilibrium to quantum nonequilibrium systems. Finally we introduce quantum diffusion via a response relating the current with the negative gradient of the charge density. With the aid of this response function we derive a quantum version of the Einstein relation and prove the existence of the diffusion pole in the zero-temperature electron-hole correlation function with the the long-range spatial fluctuations controlled by the static diffusion constant.Comment: 16 pages, REVTeX4, 6 EPS figure

Risk and Subsidies in Czech Agriculture - an ex-ante Analysis of Farmers´ Decision-making

This paper deals with the ex-ante analysis of the effects of farm subsidies on farm behaviour. Beside that the risk factor is implemented in the farm model to reflect and quantify potential (negative) impact on farm results. A farm-level optimization model is used to assess the effects of different kind of policies and risk on production structure, income indicators and land use management. It appeared that a reasonable level of risk (via income variation) have impact, but not significant. If liberalisation would have happened (zero direct and disadvantageous payments) production would homogenised, 30% of land would remained abandoned, production and income would clearly decline. Other scenario points out that environmental objectives (here through more extensively managed land) could not be necessarily more costly, but in such a case without accompanying livestock. To increase profitable livestock production requires to provide grassland and animal payments above the current level (obviously in addition to stimulating production economizing) whereas both payments should be conditional to each other.Agrarian policy, risk assessment, farm model, direct payments, Agricultural and Food Policy, Farm Management, GA, IN,

Kinetic equation for strongly interacting dense Fermi systems

We review the non-relativistic Green's-function approach to the kinetic equations for Fermi liquids far from equilibrium. The emphasis is on the consistent treatment of the off-shell motion between collisions and on the non-instant and non-local picture of binary collisions. The resulting kinetic equation is of the Boltzmann type, and it represents an interpolation between the theory of transport in metals and the theory of moderately dense gases. The free motion of particles is renormalised by various mean field and mass corrections in the spirit of Landau's quasiparticles in metals. The collisions are non-local in the spirit of Enskog's theory of non-ideal gases. The collisions are moreover non-instant, a feature which is absent in the theory of gases, but which is shown to be important for dense Fermi systems. In spite of its formal complexity, the presented theory has a simple implementation within the Monte-Carlo simulation schemes. Applications in nuclear physics are given for heavy-ion reactions and the results are compared with the former theory and recent experimental data. The effect of the off-shell motion and the non-local and non-instant collisions on the dynamics of the system can be characterised in terms of thermodynamic functions such as the energy density or the pressure tensor. Non-equilibrium counterparts of these functions and the corresponding balance equations are derived and discussed from two points of view. Firstly, they are used to prove the conservation laws. Secondly, the role of individual microscopic mechanisms in fluxes of particles and momenta and in transformations of the energy is clarified.Comment: Boo

POVMs: a small but important step beyond standard quantum mechanics

It is the purpose of the present contribution to demonstrate that the generalization of the concept of a quantum mechanical observable from the Hermitian operator of standard quantum mechanics to a positive operator-valued measure is not a peripheral issue, allegedly to be understood in terms of a trivial nonideality of practical measurement procedures, but that this generalization touches the very core of quantum mechanics, viz. complementarity and violation of the Bell inequalities.Comment: Contribution to Proceedings of the Workshop `Beyond the quantum', Leiden, May/June 200

Quantifying the effectiveness of silver ring splints to correct swan-neck deformity

Swan-neck deformity is a common symptom of rheumatoid arthritis affecting the fingers. It can be classified by hyperextension of the proximal interphalangeal (PIP) joint and flexion of the distal interphalangeal joint [1]. Methods to correct hyperextension of the PIP joint range from surgery to splinting techniques [2]. Silver ring splints (SRSs) were recently identified as a possible alternative to surgery and traditional thermoplastic splints because patient adherence was improved by their appearance [3]. The objective of this study was to investigate whether the SRSs restrict PIP joint hyperextension during a fine dexterity task

A time-dependent approach to electron pumping in open quantum systems

We propose a time-dependent approach to investigate the motion of electrons in quantum pump device configurations. The occupied one-particle states are propagated in real time and used to calculate the local electron density and current. An advantage of the present computational scheme is that the same computational effort is required to simulate monochromatic, polychromatic and nonperiodic drivings. Furthermore, initial state dependence and history effects are naturally accounted for. This approach can also be embedded in the framework of time-dependent density functional theory to include electron-electron interactions. In the special case of periodic drivings we combine the Floquet theory with nonequilibrium Green's functions and obtain a general expression for the pumped current in terms of inelastic transmission probabilities. This latter result is used for benchmarking our propagation scheme in the long-time limit. Finally, we discuss the limitations of Floquet-based schemes and suggest our approach as a possible way to go beyond them.Comment: 14 pages, 8 figure