Models of travel demand with endogenous preference change and heterogeneous agents

In the literatures of regional science, urban economics, and urban development planning, a working assumption is that individuals respond to incentives and regulations, given their preferences. Models for planning and policy analyses are used to consider what might occur if the incentives or regulations were different. In these models, however, preferences are usually assumed to be given and stable, and agents are usually assumed to be homogeneous. This paper focuses on the implications of making preferences in models of policy implementation endogenously determined and time varying heterogeneous agents. We consider first the recent literature on intertemporal choice and preference change, which cuts across many disciplines, and more briefly the literature on norm-regarding behavior. We then elaborate a simple model of transportation demand—from a static to a dynamic orientation, from fixed and exogenously given preferences of strictly self-regarding agents to endogenously determined and policy-induced preferences of heterogeneous agents—and illustrate its characteristics with simple numerical examples.     

Biosorption of Rare-Earth Elements and Yttrium by Heterotrophic Bacteria in an Aqueous Environment

This paper reports the results of the experimental determination of the coefficient of sorption of rare-earth elements and yttrium (REY) under conditions of acidic pH using several strains of heterotrophic bacteria (Microbacterium sp., Curtobacterium sp., Bacillus subtilis, Pseudomonas putida, and Bacillus pumilis) that are widespread in natural and technogenic waters of the Far East (Russia). Insignificant fractionation between heavy and light rare-earth elements, negative cerium and dysprosium anomalies, and a positive europium anomaly were revealed. The selectivity of REY biosorption by gram-positive and gram-negative bacteria, as well as inertia of the biosorption process under more acidic conditions of the medium, were shown.     

PGE distribution in deformed lherzolites of the Udachnaya kimberlite pipe (Yakutia)

The results of the first study of the PGE distribution in deformed lherzolites of the Udachnaya kimberlite pipe (Yakutia) are presented here. The complex character of evolution of the PGE composition in the Deformed lherzolites is assumed to be the result of silicate metasomatism. At the first stage, growth in the amount of clinopyroxene and garnet in the rock is accompanied by a decrease in the concentration of the compatible PGE (Os, Ir). During the final stage, the rock is enriched with incompatible PGE (Pt, Pd) and Re possible due to precipitation of submicron-sized particles of sulfides in the interstitial space of these mantle rocks.     

Optical properties of dust from Jupiter family comets

To try to define specific physical properties of the dust of Jupiter-family comets (JFCs), we compare the light scattered by them. Amongst the more than 1000 JFCs, less than 200 are numbered, 40 of them being rather bright. In the present work we use data from the latter. In situ observations of three nuclei show low albedo surfaces. The albedo of the dust particles in the coma is low, with generally a red colour. The A(α)fρ product is a measure of cometary activity and secular changes. Images of different regions (jets and fans) give indications on the nucleus rotation and position of the emitting areas, as compared to the position of the rotation axis. Differences in physical properties between the particles in different regions are pointed out by differences in the linear polarization of the scattered light and by spectral variations in brightness and polarization. Jupiter family comets are considered as dust-poor comets. Tails and trails’ studies give an estimation of the size distribution of the particles. However the dust production rates depend on the largest particles (up to centimetre size), which are mainly observed in the trails where large dark compact particles are found. These dark particles are also responsible for the high polarization in the inner most coma of some comets. The meaning, in terms of physical properties, of the linear polarization is discussed through different examples such as 2P/Encke, 9P/Tempel 1 or the fragments of 73P/Schwassmann-Wachmann 3. Cometary outbursts and splitting events show that the properties of the dust ejected from the interior of the nucleus are similar to the ones of more active comets (new or with larger semi-major axis).