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International audience; In poor developing countries, the discovery of large gas deposits often stimulates the public authorities' appetite for ambitious development strategies requiring the construction of a large national pipeline system. However, the foreign private investors financing its installation usually prefer smaller infrastructure designs that are solely intended to supply a few creditworthy industrial sites. Focusing on the situation in Mozambique, we examine whether the adoption of rate-of-return (RoR) regulation can reconcile these conflicting objectives. As a first step, we assess the magnitude of the overcapitalization generated ex ante at the planning stage by the application of RoR regulation (i.e., the Averch-Johnson effect) to the investors. Then, analyzing the ex post situation when the enlarged domestic demand materializes, we prove that the allowable rate of return can be set by the regulator to obtain ex ante the degree of overcapitalization needed ex post to serve the enlarged demand in a cost-efficient manner. We finally discuss whether RoR regulation can still protect society from monopoly prices when it is tuned to prompt an optimal degree of building ahead of proven demand.

International audience; This note details a complete microeconomic characterization of the physical relationships between input use and the level of output of a simple point-to-point gas pipeline system and uses it to contribute to the public policy discussions pertaining to the economic regulation of natural gas pipelines. We show that the engineering equations governing the design and operations of that infrastructure can be approximated by a single production equation of the Cobb-Douglas type. We use that result to inform three public policy debates. First, we prove that the long-run cost function of the infrastructure formally verifies the condition for a natural monopoly, thereby justifying the need of regulatory intervention in that industry. Second, we examine the conditions for cost-recovery in the short-run and contribute to the emerging European discussions on the implementation of short-run marginal cost pricing on interconnector pipelines. Lastly, we analyze the performance of rate-of-return regulation in that industry and inform the regulatory policy debates on the selection of an appropriate authorized rate of return. We highlight that, contrary to popular belief, the socially desirable rate of return can be larger than the market price of capital for that industry.

This paper examines the deployment of a natural gas pipeline in a developing region where the rate-of-return (RoR) regulation has been implemented to attract investment. We assume that the pipeline firm considers the proven demand emanating from a few large industrial sites but ignores the eventual rise of other domestic-oriented uses. We first assess the magnitude of the overcapitalization generated ex ante at the planning stage by the application of RoR regulation (i.e., the Averch-Johnson effect). We then analyze the ex-post situation when the enlarged domestic demand materializes. We prove that the allowable rate of return can be set to obtain ex ante the degree of overcapitalization needed ex post to serve the enlarged demand in a costefficient manner. We finally discuss whether RoR regulation can fulfill two public policy objectives: optimally building ahead of proven demand and protecting society from monopoly prices.

Promising as a gene carrier, the Foamy virus (FV) is an atypical retrovirus that shares similarities with HIV and the hepatitis B virus. Despite numerous biochemical studies, its entry pathway remains unclear, namely whether entry occurs through fusion at the plasma membrane or after endocytosis. To investigate this issue, dual-color fluorescent viruses were engineered with a GFP-labeled capsid and a mCherry-labeled envelope. Thus, the release of the capsid from the envelope would result in a loss of colocalization of the two colors at the single virus level. Using 3D single virus tracing, we followed the entry of the fluorescent viruses in living cells. In such experiments, a compromise is made between low phototoxicity for the cells and sufficient signal-to-noise ratio for tracking. Therefore, it is often difficult to rely on the fluorescence intensity to estimate colocalization. Cross-correlation approaches are highly sensitive to colocalization and coordinated motion but none of the existing methods are applicable to single particle tracking. We developed a novel approach, Tracking Image Cross-correlation (TrIC), which combines image cross-correlation and single particle tracking. The image cross-correlation analysis yields the colocalization status of the particle as well as the average distance between the two labels. The combination of this dynamical colocalization information with the instantaneous velocity of the particle and its position within the cell allows us to clarify the Foamy virus entry pathway. We compared two types of FVs and demonstrated that the prototype FV can enter the cell by either endocytosis or membrane fusion whereas the simian FV was only observed to fuse after endocytosis. Interestingly, our analysis revealed an intermediate stage during the fusion process where the capsid and envelope separate by ∼400nm but are still attached for ∼5 minutes before fusion is completed.