要旨：This paper presents an analytical framework for understanding an efficient usage of ODA to attract foreign investment, based on an economic geography model. One of the main results is that recipient countries with less trade openness should have their ODA directed more towards social infrastructure, whereas it should be shifted towards economic infrastructure if undergoing trade liberalization. The second result is that the foreign investment may outflow temporarily from less developed countries in the process of globalization. Finally, we demonstrate that these findings are consistent with statistical evidence using a dataset of 78 recipient countries for the period during 1991-2001.

要旨：日本における空港・港湾の整備と運営に関わる問題を、規模の経済、輸送頻度の経済、および補完性という概念に基づき整理した。その上で、日本においては、輸送機能を特定の空港・港湾により集中させることが望ましいと考えられることを指摘した。そのために必要なキャパシティの確保の方法について検討し、その利点と欠点について検討した。

要旨：We propose a class of Chamberlinian monopolisitic competition models that yields: (i) simple closed-form solutions for the price equilibrium; (ii) equilibrium prices which increase with production costs, increase with consumption expenditure, and decrease with the mass of competitors. We illustrate this approach with a 'constant absolute risk aversion' specification and then apply it to international trade and economic growth.

要旨：本論文では、生産において環境汚染を排出するような工業財部門とニューメレールとしての農業財を生産する2 部門の小国経済モデルを考察する。 さらに、工業財はその規模に応じて収穫一定の伝統的技術と収穫逓増の先進技術が選択可能なケースを設定する。このもとで経済全体を考える政府が汚染を排出する工業財部門に適切な環境政策をとった場合、排出される汚染は多くの実証分析で証明されてきた環境クズネッツ曲線が導出でき、その要因が工業財部門の技術の選択と関係があることを示す。 また、地域間の人口移動が生じるようなケースのついても考察し長期の地域分布にどのような影響が生じるかについて検討する。

要旨：競合する２鉄道路線の最適な快速列車停車駅の選択と、社会的厚生に与える影響についての分析

要旨：This paper explores the interplay between commodities' transportation costs and workers' commuting costs within a general equilibrium framework a la Dixit-Stiglitz. Workers are mobile and choose both a region where to live as well as an intraurban location. Contrary to general beliefs, we show that a more integrated economy need not be more agglomerated. Instead, we show that low transportation costs lead to the dispersion of economic activities. This is because firms and workers are able to alleviate the burden of urban costs by being dispersed, while retaining a good access to all varieties.

要旨：本研究では親が子に教育を施し、それにより子の所得が影響を受けるOLGモデルを、集積の経済を考慮した人口移動が常時自由な２地域モデルの枠組みで分析する。本研究の特色は、①初期状態として能力水準の等しい個人を与えても、世代交代を通して地域間で教育水準に格差のある長期均衡に到達しうる。②長期均衡において人口移動に対しロックインが働くが、とりわけ１方向の人口移動に対してのみロックインが働く、「片側ロックイン」の概念に触れ、地方が一方的な人口流出の危機にさらされる可能性を指摘する。

要旨：We analyze how the interplay between urban costs, wage wedges and trade costs may affect the inter-regional location of firms as well as the intra-urban location, within the central business district or in a secondary employment centre (SEC) of the selected region. In this way we investigate, on the one hand, how trade may affect the internal structure of cities and, on the other hand, how decentralizing the production and consumption of goods to subcentres changes the intensity of trade by allowing large metropolitan areas to maintain their predominance. We show that, despite low commuting costs SECs may emerge when the urban population is large and communication technologies are efficient, two features that seem to characterize modern economies. Moreover, when trade costs fall from high levels, the economy moves gradually from dispersion to agglomeration, favouring the formation of SECs. In an integrating world, however, the centre of a small monocentric city could be more attractive than subcentres of large polycentric cities. Nevertheless, the core retains its predominance through the relative growth of its main centre, which occurs at the expense of its subcentres.

要旨：We analyze the location decisions where three firms locate sequentially under uncertainty about consumers’ preference with spatial competition. Contrary to the results of previous studies under uncertainty about consumers’ preference, we can show that there exists equilibrium where the second firm imitates the location of the first firm, considering that firms could learn the information about consumers’ preference. Because consumers’ preference is clarified by the differentiation of locations, the second firm locates the same location as the first firm in order not to clarifying consumers’ preference.

要旨：I analyze the effects of competition on R&D effort (in a non-tournament context) and obtain robust results that hold for a variety of market structures, including markets with and without barriers to entry and markets characterized by either price or quantity competition. The approach encompasses models of direct investment to reduce costs as well as models where cost reduction arises because the agency problem between managers and owners in an asymmetric information context (X-inefficiency) is better resolved. It is found that increasing the number of firms tends to reduce R&D effort, whereas increasing the degree of product substitutability, with or without free entry, increases R&D effort―provided that the total market for varieties does not shrink. Increasing the total market size increases R&D effort.