Discussion: Applications and Innovations in Spatial Econometrics

These articles provide a discussion of studies presented in a session on spatial econometrics, focusing on the ability of spatial regression models to quantify the magnitude of spatial spillover impacts. Both articles presented argue that a proper modeling of spatial spillovers is required to truly understand the phenomena under study, in one case the impact of climate change on land values (or crop yields) and in the second the role of regional industry composition on regional business establishment growth.lagged variables, panel data, spatial spillovers, Community/Rural/Urban Development, Environmental Economics and Policy, Resource /Energy Economics and Policy, C33, C51,

Combining mixed logit models and random effects models to identify the determinants of willingness to pay for rural landscape improvements

This paper reports the findings from a discrete choice experiment study designed to estimate the economic benefits associated with rural landscape improvements in Ireland. Using a mixed logit model, the panel nature of the dataset is exploited to retrieve willingness to pay values for every individual in the sample. This departs from customary approaches in which the willingness to pay estimates are normally expressed as measures of central tendency of an a priori distribution. In a different vein from analysis conducted in previous discrete choice experiment studies, this paper uses random effects models for panel data to identify the determinants of the individual-specific willingness to pay estimates. In comparison with the standard methods used to incorporate individual-specific variables into the analysis of discrete choice experiments, the analytical approach outlined in this paper is shown to add considerably more validity and explanatory power to welfare estimatesAgri-environment, discrete choice experiments, mixed logit, panel data, random effects, willingness to pay, Demand and Price Analysis, Environmental Economics and Policy, C33, C35, Q24, Q51,

Current account benchmarks for central and eastern Europe: a desperate search?

This paper examines two competing approaches for calculating current account benchmarks, i.e. the external sustainability approach á la Lane and Milesi-Ferretti (LM) versus the structural current accounts literature (SCA) based on panel econometric techniques. The aim is to gauge the medium term adjustment in current account positions that may be required in some central and eastern European countries. As regards the LM approach, we show how the outcome is especially sensitive to (i) the normative choice for external indebtedness and (ii) the decision to exclude the foreign direct investment subcomponent from the NFA aggregate. Turning our search to the SCA approach, we assess its sensitivity to model and parameter uncertainty by setting different selection criteria to choose amongst the over 8000 possible combinations of fundamentals. Furthermore, to test the robustness of our findings we combine all models, attaching to each a probability (Bayesian Averaging of Classical Estimates). We show both the LM and SCA methodologies are not immune from severe drawbacks and conceptual difficulties. Nevertheless pulling together the results of both approaches point to the countries that may need a current account adjustment over a medium term horizon. JEL Classification: C11, C33, F15, F32, F34, F41, O52Capital flows, central and eastern Europe, current account, financial integration, model combination, Model uncertainty, panel data

Transferable Pair Potentials for CdS and ZnS Crystals

A set of interatomic pair potentials is developed for CdS and ZnS crystals. We show that a simple energy function, which has been used to describe the properties of CdSe [J. Chem. Phys. 116, 258 (2002)], can be parametrized to accurately describe the lattice and elastic constants, and phonon dispersion relations of bulk CdS and ZnS in the wurtzite and rocksalt crystal structures. The predicted coexistence pressure of the wurtzite and rocksalt structures, as well as the equation of state are in good agreement with experimental observations. These new pair potentials enable the study of a wide range of processes in bulk and nanocrystalline II-VI semiconductor materials

Deprojection of light distributions of nearby systems: perspective effect and non-uniqueness

Deriving the 3-dimensional volume density distribution from a 2-dimensional light distribution of a system yields generally non-unique results. The case for nearby dust-free systems is studied, taking into account the extra constraints from the perspective effect. It is shown analytically that a new form of non-uniqueness exists. We can design a Phantom Spheroid (PS) for a nearby system which preserves the intrinsic mirror symmetry and projected surface brightness of the system while changing the shape and the major-axis orientation of the system. A family of analytical models are given as functions of the distance ($D_0$) to the object and the amount ($\gamma$) of the superimposed PS density. The PS density, different from the well-known konuses of extragalactic systems, makes the luminosity of the system vary slightly with the distance $D_0$. The physical ranges for $\gamma$ and the major axis angles are constrained analytically by requiring a positive volume density everywhere. These models suggest that observations other than surface brightness maps are required to lift the degeneracy in the tilt angles and axis ratio of the central bar of the Milky Way.Comment: 21 single-spaced pages including 12 figures. Submitted to MNRA

Physical Properties of Iron in the Inner Core

The Earth's inner core plays a vital role in the dynamics of our planet and is itself strongly exposed to dynamic processes as evidenced by a complex pattern of elastic structure. To gain deeper insight into the nature of these processes we rely on a characterization of the physical properties of the inner core which are governed by the material physics of its main constituent, iron. Here we review recent research on structure and dynamics of the inner core, focusing on advances in mineral physics. We will discuss results on core composition, crystalline structure, temperature,and various aspects of elasticity. Based on recent computational results, we will show that aggregate seismic properties of the inner core can be explained by temperature and compression effects on the elasticity of pure iron, and use single crystal anisotropy to develop a speculative textural model of the inner core that can explain major aspects of inner core anisotropy.Comment: 23 pages, 16 figures. To appear in AGU Geodynamics Series book on "Core structure, dynamics, and rotation", V. Dehant et al. (eds.

Structure and elastic properties of Mg(OH)2_2 from density functional theory

The structure, lattice dynamics and mechanical properties of the magnesium hydroxide have been investigated with static density functional theory calculations as well as \it {ab initio} molecular dynamics. The hypothesis of a superstructure existing in the lattice formed by the hydrogen atoms has been tested. The elastic constants of the material have been calculated with static deformations approach and are in fair agreement with the experimental data. The hydrogen subsystem structure exhibits signs of disordered behaviour while maintaining correlations between angular positions of neighbouring atoms. We establish that the essential angular correlations between hydrogen positions are maintained to the temperature of at least 150 K and show that they are well described by a physically motivated probabilistic model. The rotational degree of freedom appears to be decoupled from the lattice directions above 30K

Spatial and non spatial approaches to agricultural convergence in Europe

The paper starts from the critiques to the Barro-style methodology for convergence analysis with the aim of reviewing the econometric approaches for testing spatial effects in convergence process related to both cross sectional and panel data regressions, a framework that is applied to a sample of 80 regions of the EU-15 at NUTS-2 level over the time period from 1980 to 2007. The empirical analysis compares results from approaches and, at the same time, provides empirical evidence from techniques that are now widely recognised in the understanding of regional growth and the influence of space but never or rarely applied to the agricultural context. Results point out the complexity of the process of agricultural regional convergence in Europe that cannot be adequately captured by the non-spatial growth regression models that have dominated the research and policy debate in this field. Evidence for convergence and spatial dependence emerges especially when estimations refers to spatial panel models while the effects of spatial heterogeneity and the existence of convergence clubs come out from the geographically weighted regression approach. The paper represents a point of departure for further researches in this field whose most important directions are underlined.Convergence, Spatial approaches, Non spatial approaches, Community/Rural/Urban Development, C21, C33, Q19.,

What happened to efficiency in electricity industries after reforms?

The last two decades have witnessed widespread power market reforms in both developed and developing countries that have cost billions of dollars. Among the key aims (and assumptions) of these reforms, there has always been realization of improvements in power sector efficiency. This paper questions the validity of this hypothesis. Using panel data from 92 countries covering the period 1982–2008, empirical models are developed and analyzed. The research findings suggest that the impact of the reforms on electricity industry performance is statistically significant but also limited. The results imply that, after controlling for country-specific variables, application of liberal market models in electricity industries slightly increases efficiency in power sector. Besides, we detect a positive relationship between reform process and the percentage share of network (transmission and distribution) losses in total electricity supplied; meaning that as countries take more reform steps the network losses as a fraction of power generated tend to increase. Moreover, the study puts forward that income level and other country specific features are more important determinants of industry efficiency than the reform process. Overall, contrary to expectations of substantial increases in sector efficiency, the paper concludes that introducing a decentralized market model with competition in the electricity sector has a limited increasing effect on power industry performance.Models with panel data (C33); model construction and estimation (C51); electric utilities (L94); power market reform; electricity industry efficiency