Using Non-parametric Methods in Econometric Production Analysis: An Application to Polish Family Farms

Econometric estimation of production functions is one of the most common methods in applied economic production analysis. These studies usually apply parametric estimation techniques, which obligate the researcher to specify the functional form of the production function. Most often, the Cobb-Douglas or the Translog production function is used. However, the specification of a functional form for the production function involves the risk of specifying a functional form that is not similar to the “true” relationship between the inputs and the output. This misspecification might result in biased estimation results—including measures that are of interest of applied economists, such as elasticities. Therefore, we propose to use nonparametric econometric methods. First, they can be applied to verify the functional form used in parametric estimations of production functions. Second, they can be directly used for estimating production functions without specifying a functional form and thus, avoiding possible misspecification errors. We use a balanced panel data set of farms specialized in crop production that is constructed from Polish FADN data for the years 2004-2007. Our analysis shows that neither the Cobb-Douglas function nor the Translog function are consistent with the “true” relationship between the inputs and the output in our data set. We solve this problem by using non-parametric regression. This approach delivers reasonable results, which are on average not too different from the results of the parametric estimations but many individual results are rather different.Farm Management,

Weather derivatives as an instrument of weather risk management

Ryzyko pogodowe ma coraz większy wpływ na funkcjonowanie współczesnych przedsiębiorstw. Aby skutecznie zarządzać ryzykiem pogodowym, przedsiębiorstwa mogą korzystać z pogodowych instrumentów pochodnych. W artykule podjęto próbę klasyfikacji podmiotów, które mogłyby wykorzystać w ramach procesu zarządzania ryzykiem pogodowym instrumenty pochodne, a szczególnie opcje pogodowe. Na wstępie przedstawiono istotę ryzyka pogodowego, formułując jego definicję oraz klasyfikując to zjawisko. Następnie dokonano wyszczególnienia tych podmiotów, na które pogoda wpływa w sposób istotny. Dalej zaprezentowano opcję pogodową, zaczynając od konstrukcji tego instrumentu, poprzez historię jego funkcjonowania na rynku światowym, a kończąc na refleksjach na temat możliwości zastosowania opcji pogodowych w polskich realiach.Weather risk has an increasing impact on the functioning of today’s enterprises. To manage weather risk effectively companies may use weather derivatives. This article attempts to classify entities that could be used as part of weather risk management derivatives, especially weather derivatives. At the outset it presents the essence of weather risk, defining and classifyingthis phenomenon. This is followed by a description of those entities on which the weather has a significant effect. Next weather derivatives are presented, starting with the construction of the instrument, through the history of weather derivatives on the world market, and ending with a reflection on the applicability of weather derivatives in a Polish context

YORP torques with 1D thermal model

A numerical model of the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect for objects defined in terms of a triangular mesh is described. The algorithm requires that each surface triangle can be handled independently, which implies the use of a 1D thermal model. Insolation of each triangle is determined by an optimized ray-triangle intersection search. Surface temperature is modeled with a spectral approach; imposing a quasi-periodic solution we replace heat conduction equation by the Helmholtz equation. Nonlinear boundary conditions are handled by an iterative, FFT based solver. The results resolve the question of the YORP effect in rotation rate independence on conductivity within the nonlinear 1D thermal model regardless of the accuracy issues and homogeneity assumptions. A seasonal YORP effect in attitude is revealed for objects moving on elliptic orbits when a nonlinear thermal model is used.Comment: 15 pages, 10 figures, accepted to MNRAS, before language editin

Decomposition of Urea in the SCR Process: Combination of DFT Calculations and Experimental Results on the Catalytic Hydrolysis of Isocyanic Acid on TiO2 and Al2O3

In selective catalytic reduction (SCR) systems for diesel vehicles the injected urea solution decomposes to ammonia and isocyanic acid (HNCO), which reacts with water to another ammonia molecule and carbon dioxide over the SCR catalyst or a special urea decomposition catalyst. The second reaction step, i.e. the catalytic hydrolysis of HNCO was studied on the anatase TiO2(101) surface and Al2O3(100) surface with ab initio density functional theory (DFT) calculations using a cluster model as well as with in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) investigations and kinetic experiments. The following mechanistic pathway has been identified to be most feasible: HNCO dissociatively adsorbs on the metal oxide surface as isocyanates, which are attacked by water, thereby forming carbamic acid at the surface. In a further step this intermediate is transformed to a carbamate complex, which leads to CO2 desorption and consequently NH3 formation. The comparison between the sum of the theoretical vibrational spectra of the reaction intermediates with the in situ DRIFT spectra also strongly supports the accuracy of the second reaction pathway. This mechanism holds also for the HNCO hydrolysis over γ-Al2O3 and the reactivity compared to TiO2 was found to be consistent with the heights of the barriers in the energy diagrams. Based on these promising preliminary results a computational screening has been started in order to predict the most active metal oxides and surfaces for this reactio

Directed percolation effects emerging from superadditivity of quantum networks

Entanglement indcued non--additivity of classical communication capacity in networks consisting of quantum channels is considered. Communication lattices consisiting of butterfly-type entanglement breaking channels augmented, with some probability, by identity channels are analyzed. The capacity superadditivity in the network is manifested in directed correlated bond percolation which we consider in two flavours: simply directed and randomly oriented. The obtained percolation properties show that high capacity information transfer sets in much faster in the regime of superadditive communication capacity than otherwise possible. As a byproduct, this sheds light on a new type of entanglement based quantum capacity percolation phenomenon.Comment: 6 pages, 4 figure