Two 2-cell embeddings ı : X → S and  : X → S of a connected graph X into a closed orientable surface S are congruent if there are an orientation-preserving surface homeomorphism h : S → S and a graph automorphism γ of X such that ıh = γ. Mull et al. [Proc. Amer. Math. Soc. 103(1988) 321–330] developed an approach for enumerating the congruence classes of 2-cell embeddings of a simple graph (w...

We model externality abatement as an implementation problem. A social planner would like to ensure efficient behavior among a group of agents whose actions are sources of externalities. However, the planner has limited information about the agents' preferences, and he is unable to distinguish individual agents except through their action choices. We prove that if a concavity condition on aggreg...

We study road supply by competing firms between a single origin and destination. In previous studies, firms simultaneously set their tolls and capacities while taking the actions of the others as given in a Nash fashion. Then, under some widely used technical assumptions, firms set a volume/capacity ratio that is socially optimal, and thus the level of travel time or service quality is socially...

European national policies involve a range of support measures to enhance the competitiveness of certain regions or products, inlcuding financial and institutional instruments. Some of these support measures involve environmentally counterproductive impacts. The question that rises in importance on the international agenda is how to reform these support measures, such that the original objectiv...

In this paper, we attempt to assess whether the positive effects of car ownership on employment outcomes observed in past research are causal. We match state-level data on average car insurance premiums and average per-gallon gas taxes to a nationally representative microdata sample containing information on car ownership and employment outcomes comparable to the those explored in previous rese...

We present our studies on the femtosecond electro-optic (EO) effect in high quality Cd0.88Mn0.12Te (CMT) single crystals, grown using a modified vertical Bridgman method. Our time-resolved experiments were performed using a coplanar transmission line setup, which incorporated a free-standing, low-temperature-grown GaAs photoconductive switch as a subpicosecond electrical pulse generator and the...

According to the World Health Organization, more than one million road traffic deaths occur every year throughout the world. In order to cope with this challenge, many countries have established quantified road safety targets backed up with comprehensive safety strategies. Road safety targets need to be based on reliable forecasting methods. Following the pioneering work by Elvik (2010), this p...

The routing plan of a delivery fleet is usually developed a priori and provides an optimal (or near optimal) way of serving customers by taking into account certain constraints, such as vehicle capacity and delivery time windows. However, such plans may not cope adequately in a city logistics environment, in which unexpected events often occur during delivery execution (e.g. adverse traffic con...

Air transport has experienced phenomenal growth in China over the last 30 years, but studies on China’s airport development are few. This paper aims to fill in this literature gap by focusing on the determinants of airport development in the Chinese regions using the most up-to-day and comprehensive data on China’s airports and their related economic and geographical variables. The empirical re...

This paper analyzes the relation between commuting time and specific health outcomes using the GSOEP and the BHPS. Both countries are in the top three of European countries in which commuting time is largest. First, we analyze whether commuting time affects specific health outcomes. We analyze both subjective health outcomes like health satisfaction and health status, and objective measures lik...