Two-Party Competition with Persistent Policies

This paper studies the Markov perfect equilibrium outcomes of a dynamic game of electoral competition between two policy-motivated parties. I model incumbent policy persistence: parties commit to implement a policy for their full tenure in office, and hence in any election only the opposition party renews its platform. In equilibrium, parties alternate in power and policies converge to symmetric alternations about the median voter's ideal policy. Parties' disutility from opponents' policies leads to alterna- tions that display bounded extremism; alternations far from the median are never limits of equilibrium dynamics. Under a natural restriction on strategies, I find that robust long-run outcomes display bounded moderation; alternations close to the median are reached in equilibrium only if policy dynamics start there. I show that these results are robust to voters being forward-looking, the introduction of term limits, costly policy adjustments for incumbents, and office benefits.

Keeping Your Options Open

In standard models of experimentation, the costs of project development consist of (i) the direct cost of running trials as well as (ii) the implicit opportunity cost of leaving alternative projects idle. Another natural type of experimentation cost, the cost of holding on to the option of developing a currently inactive project, has not been studied. In a (multi-armed bandit) model of experimentation in which inactive projects have explicit maintenance costs and can be irreversibly discarded, I fully characterise the optimal experimentation policy and show that the decision-maker's incentive to actively manage its options has important implications for the order of project development. In the model, an experimenter searches for a success among a number of projects by choosing both those to develop now and those to maintain for (potential) future development. In the absence of maintenance costs, the optimal experimentation policy has a 'stay-with-the-winner' property: the projects that are more likely to succeed are developed first. Maintenance costs provide incentives to bring the option value of less promising projects forward, and under the optimal experimentation policy, projects that are less likely to succeed are sometimes developed first. A project development strategy of 'going-with-the-loser' strikes a balance between the cost of discarding possibly valuable options and the cost of leaving them open.

Perflubron Distribution During Transition From Gas to Total Liquid Ventilation

Total liquid ventilation (TLV) using perfluorocarbons has shown promising results for the management of neonatal respiratory distress. However, one important safety consideration for TLV is a better understanding of the early events during the transition to TLV, especially regarding the fate of residual air in the non-dependent-lung regions. Our objective was to assess perflubron distribution during transition to TLV using electrical impedance tomography, complemented by fluoroscopy, in a neonatal lamb model of induced surfactant deficiency. Eight lambs were anesthetized and ventilated in supine position. Surfactant deficit was induced by saline lung lavage. After deflation, lungs were filled with 25 ml/kg perflubron over 18 s, and TLV was initiated. Electrical impedance tomography data was recorded from electrodes placed around the chest, during the first 10 and at 120 min of TLV. Lung perfusion was also assessed using hypertonic saline injection during apnea. In addition, fluoroscopic sequences were recorded during initial lung filling with perfluorocarbons, then at 10 and 60 min of TLV. Twelve lambs were used as controls for histological comparisons. Transition to TLV involved a short period of increased total lung volume (p = 0.01) secondary to recruitment of the dependent lung regions. Histological analysis shows that TLV was protective of these same regions when compared to gas-ventilated lambs (p = 0.03). The non-dependent lung regions filled with perflubron over at least 10 min, without showing signs of overdistention. Tidal volume distribution was more homogenous in TLV than during the preceding gas ventilation. Perflubron filling was associated with a non-significant increase in the anterior distribution of the blood perfusion signal, from 46 ± 17% to 53 ± 6% (p = 0.4). However, combined to the effects on ventilation, TLV had an instantaneous effect on ventilation-perfusion relationship (p = 0.03), suggesting better coupling. Conclusion: transition to TLV requires at least 10 min, and involves air evacuation or dissolution in perflubron, dependent lung recruitment and rapid ventilation-perfusion coupling modifications. During that time interval, the total lung volume transiently increases. Considering the potential deleterious effect of high lung volumes, one must manage this transition phase with care and, we suggest using a real-time monitoring system such as electrical impedance tomography

Essays in Political Economy and the Economics of Organisations

This thesis groups three papers in applied microeconomic theory that focus on political economy and the economics of organisations. The first chapter studies the equilibrium outcomes of a dynamic game of electoral competition between two policy-motivated parties. I model incumbent policy persistence: parties commit to implement a policy for their full tenure in office, and hence in any election only the opposition party is free to choose a new platform. The model gives rise to novel equilibrium policy dynamics: governments alternate in power; parties compromise, that is, starting from differentiated ideological positions, they gradually move towards proposing platforms which resemble one another; however, they never capitulate, that is, party labels matter and parties maintain distinct policy goals. The second chapter studies a directed search model of competition between sellers that control the quality of buyers' private information about goods. As better informed buyers extract more informational rents from trade, sellers may try to attract buyers by offering better information. First, I establish how the characteristics of exogenously fixed sale mechanisms determine equilibrium information provision. Information provision is higher under competition than under monopoly, yet partial information is provided for many sale mechanisms. Second, when sellers commit to both information provision and mechanisms, I identify simple conditions under which every equilibrium has full information. In these equilibria, sellers capture the efficiency gains of information provision and compete only over non-distortionary rents offered to buyers. Retaining the option to develop a currently inactive project often requires maintaining specialised stocks of knowledge. However, standard models of experimentation treat the choice of one project over another as entailing only an implicit opportunity cost. In the third chapter, I characterise the optimal experimentation policy in a model in which undeveloped projects have explicit maintenance costs and can be irreversibly discarded. Projects which in the absence of maintenance costs would be developed only after more promising projects fail are sometimes developed first and then discarded early. Maintenance costs alter optimal project development by providing incentives to bring the option value of less promising projects forward.Ph

Fixed-point approaches to the proof of the Bondareva–Shapley Theorem

We provide two new proofs of the Bondareva–Shapley theorem, which states that the core of a transferable utility cooperative game has a nonempty core if and only if the game is balanced. Both proofs exploit the fixed points of self-maps of the set of imputations, applying elementary existence arguments typically associated with noncooperative games to cooperative games

Disruption of the Phosphate Transporter Pit1 in Hepatocytes Improves Glucose Metabolism and Insulin Signaling by Modulating the USP7/IRS1 Interaction

International audienceThe liver plays a central role in whole-body lipid and glucose homeostasis. Increasing dietary fat intake results in increased hepatic fat deposition, which is associated with a risk for development of insulin resistance and type 2 diabetes. In this study, we demonstrate a role for the phosphate inorganic transporter 1 (PiT1/SLC20A1) in regulating metabolism. Specific knockout of Pit1 in hepatocytes significantly improved glucose tolerance and insulin sensitivity, enhanced insulin signaling, and decreased hepatic lipogenesis. We identified USP7 as a PiT1 binding partner and demonstrated that Pit1 deletion inhibited USP7/IRS1 dissociation upon insulin stimulation. This prevented IRS1 ubiquitination and its subsequent proteasomal degradation. As a consequence, delayed insulin negative feedback loop and sustained insulin signaling were observed. Moreover, PiT1-deficient mice were protected against high-fat-diet-induced obesity and diabetes. Our findings indicate that PiT1 has potential as a therapeutic target in the context of metabolic syndrome, obesity, and diabetes

Assessing the impacts of total liquid ventilation on left ventricular diastolic function in a model of neonatal respiratory distress syndrome.

Filling the lung with dense liquid perfluorocarbons during total liquid ventilation (TLV) might compress the myocardium, a plausible explanation for the instability occasionally reported with this technique. Our objective is to assess the impacts of TLV on the cardiovascular system, particularly left ventricular diastolic function, in an ovine model of neonatal respiratory distress syndrome.Eight newborns lambs, 3.0 ± 0.4 days (3.2 ± 0.3kg) were used in this crossover experimental study. Animals were intubated, anesthetized and paralyzed. Catheters were inserted in the femoral and pulmonary arteries. A high-fidelity pressure catheter was inserted into the left ventricle. Surfactant deficiency was induced by repeated lung lavages with normal saline. TLV was then conducted for 2 hours using a liquid ventilator prototype. Thoracic echocardiography and cardiac output assessment by thermodilution were performed before and during TLV.Left ventricular end diastolic pressure (LVEDP) (9.3 ± 2.1 vs. 9.2 ± 2.4mmHg, p = 0.89) and dimension (1.90 ± 0.09 vs. 1.86 ± 0.12cm, p = 0.72), negative dP/dt (-2589 ± 691 vs. -3115 ± 866mmHg/s, p = 0.50) and cardiac output (436 ± 28 vs. 481 ± 59ml/kg/min, p = 0.26) were not affected by TLV initiation. Left ventricular relaxation time constant (tau) slightly increased from 21.5 ± 3.3 to 24.9 ± 3.7ms (p = 0.03). Mean arterial systemic (48 ± 6 vs. 53 ± 7mmHg, p = 0.38) and pulmonary pressures (31.3 ± 2.5 vs. 30.4 ± 2.3mmHg, p = 0.61) were stable. As expected, the inspiratory phase of liquid cycling exhibited a small but significant effect on most variables (i.e. central venous pressure +2.6 ± 0.5mmHg, p = 0.001; LVEDP +1.18 ± 0.12mmHg, p<0.001).TLV was well tolerated in our neonatal lamb model of severe respiratory distress syndrome and had limited impact on left ventricle diastolic function when compared to conventional mechanical ventilation