International trade, exports, imports, firm heterogeneity, productivity, import premium, export premium,
Resistivity and induced polarization (IP) measurements on soil contaminated with non-aqueous phase liquids (NAPLs) show a great variety in results in previous research. Several laboratory studies have suggested that the presence of NAPLs in soil samples generally decrease the magnitude of the IP-effect, while others have indicated the opposite. A number of conceptual models have been proposed suggesting that NAPLs can alter the pore space in different ways, e.g. by coating the grain surfaces and thus inhibiting grain polarization, or by changing the pore throat size and thus affecting the membrane polarization mechanism. The main aim of this paper is to review previously published conceptual models and to introduce some new concepts of possible residual NAPL configurations in the pore space. Time domain induced polarization measurements were performed at a NAPL contaminated field site, and the data were inverted using the Constant Phase Angle (CPA) model and the Cole-Cole model respectively. No significant phase anomalies were observed in the source area of the contamination when the CPA inverted profiles were compared with soil sampling results of free-phase contaminant concentrations. However, relatively strong phase and normalized phase anomalies appeared next to the source area, where residual free-phase presence could be expected according to the chemical data. We conclude that depending on the NAPL configuration, different spectral IP responses can be expected. In previous research, the NAPL configurations in different samples or field sites are often unknown, and this may to some extent explain why different results have been achieved by different authors. In our field case, we believe that the NAPL forms a more or less continuous phase in the pore space of the source zone leading to an absence of IP anomalies. The increase in phase and normalized phase angle observed next to the source zone is interpreted as a degradation zone. The ongoing biodegradation may have led to a fractionation of the continuous NAPL in the outer part of the original source zone, leading to residual presence of isolated NAPL droplets in the soil pores. With such NAPL configurations, an increased polarization can be expected according to the electrochemical-and membrane polarization mechanisms. More research is needed to confirm the effects of different NAPL configuration on spectral IP parameters.
This paper explores the patterns of innovation and collaboration by using unique regional survey data on more than 600 Swedish firms. The data also include the smallest firms, which have been largely neglected in the existing literature on innovations. In the context of collaboration, however, small firms are of particular interest because external interactions and joint projects can be expected to play a very central role in innovation processes in firms where internal resources are very limited. The results show that the probability of innovation is higher among collaborating firms, yet not all types of collaborations matter. Extra-regional collaborations appear as most important in promoting firm innovation, and collaboration seems to be most favourable when the partners involved have some organizational or knowledge relatedness. Small firms, in particular, seem to gain from such extra-regional linkages. JEL Classification
This paper analyses determinants of agricultural land prices in Sweden with a particular focus on location-specific factors. An asset-pricing model is used to decompose agricultural land prices into expected returns from land in its current agricultural use and expected returns from its potential use. The model is estimated in a cross regional context where explanatory factors relate to regional variations in land productivity, agricultural support payments and urbanising influences. Results indicate that both agricultural and non-agricultural factors are influential determinants to the price of agricultural land. Estimating marginal effects across the distribution of the dependent variable, non-agricultural factors are shown to be more important in regions that have high agricultural land prices, whereas, income support to farmers in the form of the decoupled single farm payment is shown to be most influential in regions with low agricultural land prices.Keywords Land price · Asset pricing · Single farm payment · Quantile regression
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