Pareto-improving toll adjustment for a buildoperate-transfer toll road project with unknown demand

The social welfare gain and investment return are two main concerns of a road investment project, and they are usually key components of a Build-operate-transfer (BOT) contract. Therefore, the Pareto efficient outcomes of the two objectives are attractive for both government and private investor. This paper proposes a ex-post toll adjustment procedure called Paretoimproving trial-and-error procedure (PI-TEP), in order to achieve the Pareto efficient outcomes for a BOT toll road project with pre-determined road capacity and unknown demand function. The PI-TEP is novel and Pareto-improving, since the procedure does not require an analytical demand function and can improve social welfare and revenue simultaneously. Furthermore, the PI-TEP is theoretically proved to be efficient in obtaining the Pareto efficient outcomes. And thus, the procedure is practically useful and valuable for both government and private investor in a BOT toll road project

Risk management in liner ship fleet deployment: a joint chance constrained programming model

This paper provides a tangible methodology to deal with the liner ship fleet deployment problem aiming at minimizing the total cost while maintaining a service level under uncertain container demand. The problem is first formulated as a joint chance constrained programming model, and the sample average approximation method and mixed-integer programming are used to deal with it. Finally, a numerical example of a liner shipping network is carried out to verify the applicability of the proposed model and solution algorithm. It is found that the service level has significant effect on the total cost

Economic analysis of highway franchising

Private provision of public roads through build-operate-transfer (BOT) contracts is increasing around the world in both developed and developing countries. Under a BOT contract, a private firm builds and operates roads in a road network at its own expense, and in return receives the revenue from road tolls for a number of years. Then these roads are transferred to the government. Important issues are the length of the concession period, capacity, toll charges and the benefits to the private investor, road users and the whole society under various market conditions and government regulations. Several issues related to a BOT toll road project are studied. This thesis first develops a benchmark analysis of the BOT road contract viewed as a combination of concession period, road capacity and toll charge under the assumption that the demand and cost functions are known to both public and private sectors. A bi-objective optimization problem is proposed for maximizing social welfare and private profit. And the properties of the concession period, service quality, social welfare and profit gains along the Pareto-optimal frontier are studied. A variety of government regulatory regimes are also investigated. We prove that: the private sector tends to offer a lower road capacity and a lower service quality under the price-cap regulation, while it chooses a higher service quality, a higher capacity and a higher toll charge under the rate-of-return regulation than those associated with the corresponding Pareto-efficient solution. In contrast, we prove that both the demand and markup charge regulations lead to Pareto-optimal outcomes. User heterogeneity in value-of-time (VOT) has long been a fascinating issue in road pricing studies. This thesis investigates the effects of the user VOT heterogeneity on the properties of the Pareto-efficient BOT contracts. Under some technical conditions, we prove that, the Pareto-optimal road-life concession period is free from the effects of user heterogeneity, while, even with constant returns to scale, the service quality is not constant and dependent on the curvature of the mean residual VOT function. The effects of user VOT heterogeneity on the outcomes of various regulatory regimes are also investigated. We find that, both the demand and markup regulations fail to achieve the Pareto-optimal outcomes and result in a lower level of capacity and service quality. In the presence of traffic uncertainty, this thesis proposes the BOT contract with full and partial flexibility according to the instruments adopted by the public and private sectors. Full flexibility refers to the case in which the public sector promises an exogenous rate of return on the private investment and in turn can freely ex post adjust the contract in a socially optimal manner according to the observed demand curve. Partial flexibility refers to the case where the public and private sectors agree on an ex ante demand risk allocation by contract and the ex post contract adjustment can be made contingent on a Pareto-improvement to both parties. A preferred Pareto-improvement can be selected from the Pareto-optimal solution set of a bi-objective programming problem equipped with a rational preference. In comparison with the traditional rigid contract, in which, private sector burdens all project risk, the proposed flexibility of the BOT contract is valuable for the contract adjustment mechanism to solve the discrepancy between the public and private sectors. Two other issues are also investigated in this thesis. One is how to select the optimal combination of concession period, capacity and toll levels for a BOT toll road project if the yearly increasing operation costs are incorporated in the project. Another is how to choose the capacity and toll levels of an ”add-on” toll road parallel to an existing one with various ownership regimes, namely the existing road can be a free, public or private toll road

Molecular analyses of chondrocyte differentiation and adaptation to ER stress

Endochondral bone development depends on the progression of chondrocyte proliferation, hypertrophy and terminal differentiation, which requires precise transcriptional regulation and signaling coordination. Disturbance of this process would disrupt chondrocyte differentiation and lead to chondrodysplasias. In cells, a highly conserved mechanism, ER stress signaling, has been developed to sense the protein load and maintain the cellular homeostasis. In humans, mutations in COL10A1 induce ER stress and result in metaphyseal chondrodysplasia type Schmid (MCDS). Previous analysis of a MCDS mouse model (13deltg mouse) had revealed a novel mechanism of chondrocyte adaptation to ER stress. The hypertrophic chondrocytes survive ER stress by reverting to a pre-hypertrophic like state (Tsang et al., 2007). To dissect the underlying mechanisms that coordinate chondrocyte survival, reverted differentiation and adaptation to ER stress, different chondrocyte populations in the wild type and 13del growth plates were fractionated for global gene expression analyses. The genome-wide expression profiles of proliferating chondrocytes, prehypertrophic chondrocytes, hypertrophic chondrocytes and terminally differentiated chondrocytes in the wild type growth plate provide molecular bases to understand the processes underlying both physiological and pathological bone growth. Systematic analyses of these transcriptomic data revealed the gene expression patterns and correlation in the dynamics of endochondral ossification. Genes associated with sterol metabolism and cholesterol biosynthesis are enriched in the prehypertrophic chondrocytes. Selected genes (Wwp2, Zbtb20, Ppa1 and Ptgis) that may potentially contribute to endochondral ossification were identified differentially expressed in the growth plate. Bioinformatics approaches were applied to predict regulatory networks in chondrocytes at different differentiation stages, implying the essential and dominant roles of Sox9 in coordination of stage specific gene expression. We further confirmed that Sox9 directly regulates the transcription of Cyr61, Lmo4, Ppa1, Ptch1 and Trps1, suggesting that Sox9 integrates different steps of chondrocyte differentiation via regulation of its target genes and partially crosstalk with IHH signaling pathway. The information on gene expression and regulation from physiological growth plate provides important basis to understand the molecular defects of chondrodysplasia. The hypertrophic zone in 13del growth plate was fractionated into upper, middle and lower parts for microarray profiling, corresponding for the onset of ER stress, onset of reverted differentiation and adaptation phase. Comparative transcriptomics of wild type and 13del growth plates revealed genes related to glucose, amino acid and lipid metabolisms are up regulated in response to ER stress. Fgf21 was identified as a novel ER stress inducible factor regulated by ATF4. Removal of Fgf21 results in increasing cell apoptosis in 13del hypertrophic zone without affecting the reverted differentiation process. Up regulation of genes expression related to hypoxic stress (Slc2a1, Hyou1, Stc2 and Galectin3) in 13del hypertrophic chondrocytes suggested that survival and adaptation of chondrocytes to ER stress involve cross-regulation by other stress pathways. Our findings have provided a new insight into the mechanisms that facilitate chondrocyte survival under ER stress in vivo, and propose the integrative effects of hypoxic stress pathway during the stress adaptation process, which broaden the molecular horizons underlying chondrodysplasias caused by protein folding mutations.published_or_final_versionBiochemistryDoctoralDoctor of Philosoph

Short-term liner shipping bunker procurement with swap contracts

10.1080/03088839.2017.1375165Maritime Policy & Management452211-23

Properties of Pareto-efficient contracts and regulations for road franchising

Private provision of public roads through build-operate-transfer (BOT) contracts is increasing around the world. This paper investigates the properties of Pareto-efficient BOT contracts using a bi-objective programming approach under perfect information. Under certain conventional assumptions, we find that for any Pareto-efficient BOT contract: (1) the concession period should be set to be the whole road life: (2) the volume-capacity ratio (or the road service quality) and the average social cost per trip are constantly equal to those at the social optimum whenever there are constant returns to scale in road construction. Extensions are made to the cases with increasing (decreasing) returns to scale in road construction. A variety of regulatory regimes are investigated to analyze the behavior of the profit-maximizing private firm, and efficient regulations, including demand and markup charge regulations, are elucidated for both the public and private sectors to achieve a predetermined Pareto-optimal outcome. (C) 2009 Elsevier Ltd. All rights reserved