Publications

Résumé Air pollution is currently accountable for 40,000 deaths every year in France. The main objective of this study was to characterize the evolution of urban air pollution and its impact on mortality, by comparing two air pollution exposure periods, 2008–2010 and 2017–2019, within the Toulouse area. We also aimed to estimate the presumed health benefits had tracer pollutant concentrations reached the level indicated by the updated 2021 World Health Organization (WHO) guidelines over the 2017–2019 period. The breakdown of this health impact, according to level of social deprivation, was also assessed along with an exploration of the associated economic impacts. Several quantitative health impact studies (EQIS) were conducted by modeling population exposure to PM2.5 and NO2 within the region covered by the second Toulouse Air Protection Plan (PPA). The French European Deprivation Index (F-EDI) was used as a fine-scale indicator of social deprivation, and economic impacts were estimated by assigning a monetary value to the prevention of one death linked to air pollution. Across the area of study, average annual concentration levels decreased from 17.2 μg/m3 to 10.3 μg/m3 for PM2.5, and from 21.7 μg/m3 to 18.1 μg/m3 for NO2 between 2009 and 2019. The proportion of all causes of mortality attributable to air pollution (95% confidence interval [95% CI]) thus dropped from 15.7% [5.8; 23.8] to 7.2% [2.6; 11.2] for PM2.5 between 2009 and 2019, and it decreased from 2.7% [0.9; 4.2] to 1.9% [0.7; 2.9] for NO2 over the same period. Despite this improvement, concentrations of tracer pollutants remained above WHO 2021 guidelines, and there were still 440 annual deaths attributable to overexposure to PM2.5, which could have been avoided had these values been reached in 2019. Regarding social deprivation, a low but increasing gradient of exposure to air pollution was observed between the least and most deprived population quintiles. This led to an even greater mortality gradient attributable to air pollution between these same quintiles, and this worsened between 2009 and 2019. The annual economic gains that could have potentially been achieved, had the WHO 2021 guidelines been met, are estimated at 2,772 million euros2018 in 2009 and 1,423 million euros2018 in 2019.
Mots clés Social deprivation, Cost-benefit analysis, Mortality, Air pollution, Pollution de l&#039, air, Mortalité, Privation sociale, Analyse coût-bénéfice
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Résumé We propose a framework for the analysis of choice behaviour when the latter is made explicitly in chronological order. We relate this framework to the traditional choice theoretic setting from which the chronological aspect is absent, and compare it to other frameworks that extend this traditional setting. Then, we use this framework to analyse various models of preference discovery. We characterise, via simple revealed preference tests, several models that differ in terms of (1) the priors that the decision-maker holds about alternatives and (2) whether the decision-maker chooses period by period or uses her knowledge about future menus to inform her present choices. These results provide novel testable implications for the preference discovery process of myopic and forward-looking agents.
Mots clés Chronological choice, Preference discovery, Revealed preferences, Myopic agents, Forward-looking agents
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Résumé This paper examines the role of social interactions in contract enforcement within the postcolonial Arab world, with a specific focus on Morocco. Through extensive interviews with members of the industrial elite during the import-substituting industrialization (ISI) period, we uncover a significant risk of contractual breaches. Despite this risk, there was a reluctance to use social connections to penalize those who breached contracts. Legal recourse was also rarely pursued. Instead, business leaders leaned on their social networks to assess potential partners and resolve disputes through bilateral channels. This reliance on social ties was facilitated by the close-knit and compact nature of the business community. In the post-ISI era, characterized by a larger and more diverse industrial elite, there was a noticeable increase in contractual disputes, accompanied by a shift towards more aggressive resolution methods. We present a theoretical model that elucidates how these dynamics naturally emerge from an environment where economic and social interactions are intertwined.
Mots clés Industry, Twentieth century, Elite, Morocco
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Résumé Most studies assessing animal decision-making under risk rely on probabilities that are typically larger than 10%. To study Decision-Making in uncertain conditions, we explore a novel experimental and modelling approach that aims at measuring the extent to which rats are sensitive - and how they respond - to outcomes that are both rare (probabilities smaller than 1%) and extreme in their consequences (deviations larger than 10 times the standard error). In a four-armed bandit task, stochastic gains (sugar pellets) and losses (time-out punishments) are such that extremely large - but rare - outcomes materialize or not depending on the chosen options. All rats feature both limited diversification, mixing two options out of four, and sensitivity to rare and extreme outcomes despite their infrequent occurrence, by combining options with avoidance of extreme losses (Black Swans) and exposure to extreme gains (Jackpots). Notably, this sensitivity turns out to be one-sided for the main phenotype in our sample: it features a quasi-complete avoidance of Black Swans, so as to escape extreme losses almost completely, which contrasts with an exposure to Jackpots that is partial only. The flip side of observed choices is that they entail smaller gains and larger losses in the frequent domain compared to alternatives. We have introduced sensitivity to Black Swans and Jackpots in a new class of augmented Reinforcement Learning models and we have estimated their parameters using observed choices and outcomes for each rat. Adding such specific sensitivity results in a good fit of the selected model - and simulated behaviors that are close - to behavioral observations, whereas a standard Q-Learning model without sensitivity is rejected for almost all rats. This model reproducing the main phenotype suggests that frequent outcomes are treated separately from rare and extreme ones through different weights in Decision-Making.
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Résumé We study the behavioral determinants of COVID-19 vaccination uptake. The vaccine-pass policy, implemented in several countries in 2021, conditioned the access to leisure and consumption places to being vaccinated against COVID-19 and created an unprecedented situation where individuals’ access to consumption goods and vaccine status were interrelated. We rely on a quasi-hyperbolic discounting model to study the plausible relationships between time preference and the decision to vaccinate in such context. We test the predictions of our model using data collected from a representative sample of the French population (N = 1034) in August and September 2021. Respondents were asked about their COVID-19 vaccination status (zero, one, or two doses), as well as their economic and social preferences. Preference elicitations were undertaken online through incentivized tasks, with parallel collection of self-stated preferences. Factors associated with COVID-19 vaccination were investigated using a logistic model. Both elicited and stated impatience were found to be positively associated with COVID-19 vaccination decisions. These results suggest that impatience is a key motivational lever for vaccine uptake in a context where the vaccination decision is multidimensional and impacts the consumption potential. Results also serve to highlight the potential effectiveness of public communications campaigns based on time preferences to increase vaccination coverage.
Mots clés Health behavior, COVID-19 Vaccination, Time inconsistency, Time preferences
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Résumé Abstract This paper investigates linkage to care following community‐based screening for hepatitis B virus (HBV) in rural Senegal. HBV‐positive participants who completed a biological and clinical examination to assess liver disease and treatment eligibility were referred to a regional hospital (if eligible for treatment), invited to join the Sen‐B research cohort study (adults with detectable viral load) or referred to their local health centre (all others). Logistic regressions were conducted to investigate factors associated with (i) uptake of the scheduled post‐screening examination, and (ii) HBV management initiation. Obstacles to HBV management were identified using thematic analysis of in‐depth patient interviews. Of the 206 HBV‐positive participants, 163 (79.1%) underwent the examination; 47 of the 163 (28.8%) initiated HBV management. Women, people not migrating for >6 months/year, individuals living in households with more agricultural and monetary resources, with other HBV‐positive participants, and beneficiaries of the national cash transfer program, were all more likely to undergo the examination. The likelihood of joining the Sen‐B cohort increased with household monetary resources, but decreased with agricultural resources. Initiation of HBV management in local health centre was higher among participants with a non‐agricultural economic activity. Individuals reported wariness and confusion about HBV management content and rationale at various stages of the care continuum, in particular with respect to venous blood sampling and management without treatment. In conclusion, HBV community‐based test‐and‐treat strategies are feasible, but early loss to follow‐up must be addressed through simplified, affordable management and community support and sensitization.
Mots clés Hepatitis B surface antigen, Adjusted odds-ratios, DBS, Dried blood spots, XOF, WHO, World Health Organization, SSA, Sub-Saharan Africa, PwHBV, People living with HBV, IQR, Interquartile range, HDSS, Health and Demographic Surveillance System, HBV, Hepatitis B virus, HBsAg, Confidence interval DBS, CI, Confidence interval, Senegal, Chronic hepatitis B virus HBV infection, Linkage to care, AOR, Adjusted odds-ratios CI, West African franc, Dried blood spots HBsAg, Hepatitis B surface antigen HBV, Hepatitis B virus HDSS, Health and Demographic Surveillance System IQR, Interquartile range pwHBV, People living with HBV sSA, Sub-Saharan Africa WHO, World Health Organization XOF
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Résumé How will structural change unfold beyond the rise of services? Motivated by the observed dynamics within the service sector we propose a model of structural change in which productivity is endogenous and output is produced with two intermediate substitutable capital goods. In the productive sector the accumulation of specialized skills leads to an unbounded increase in TFP, as sector becoming asymptotically dominant. We are then able to recover the increasing shares of workers, the increasing real and nominal shares of the output observed in productive service and IT sectors in the US. Interestingly, the economy follows a growth path converging to a particular level of wealth that depends on the initial price of capital and knowledge. As a consequence, countries with the same fundamentals but lower initial wealth will be characterized by lower asymptotic wealth.
Mots clés Two-sector model, Technological knowledge, Constant elasticity ofsubstitution, Non-balanced endogenous growth, Structural change, Kaldor and Kuznets facts
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Résumé Episodes of low natural interest rates, even transitory, pose a challenge to monetary policy, by possibly causing the effective lower bound (ELB) on the policy rate to bind. Those episodes are more likely to occur not only when the natural rate is low on average but also when fluctuations around its average level are large. We study the responsiveness of the natural interest rate to structural aggregate shocks affecting the aggregate supply of and demand for savings. Using a quantitative overlapping-generations model, we trace back this responsiveness to the slopes of aggregate savings supply and demand curves and argue that both curves have likely flattened over the past four decades in the US This implies a greater sensitivity of the natural interest rate to structural shocks affecting the supply of and demand for aggregate savings – making it more likely, all else equal, that it fall into negative territory.
Mots clés Natural interest rate, Intertemporal income effects, Overlapping-generations
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Résumé We introduce a new approach to apply the boosted difference of convex functions algorithm (BDCA) for solving non-convex and non-differentiable problems involving difference of two convex functions (DC functions). Supposing the first DC component differentiable and the second one possibly non-differentiable, the main idea of BDCA is to use the point computed by the subproblem of the DC algorithm (DCA) to define a descent direction of the objective from that point, and then a monotone line search starting from it is performed in order to find a new point which decreases the objective function when compared with the point generated by the subproblem of DCA. This procedure improves the performance of the DCA. However, if the first DC component is non-differentiable, then the direction computed by BDCA can be an ascent direction and a monotone line search cannot be performed. Our approach uses a non-monotone line search in the BDCA (nmBDCA) to enable a possible growth in the objective function values controlled by a parameter. Under suitable assumptions, we show that any cluster point of the sequence generated by the nmBDCA is a critical point of the problem under consideration and provides some iteration-complexity bounds. Furthermore, if the first DC component is differentiable, we present different iteration-complexity bounds and prove the full convergence of the sequence under the Kurdyka–Łojasiewicz property of the objective function. Some numerical experiments show that the nmBDCA outperforms the DCA, such as its monotone version.
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Résumé We show that the development of abstract reasoning and cognitive empathy (theory of mind) is severely hindered when children are deprived of the stimulation of a school environment. We document significantly lower abstract reasoning and cognitive empathy scores in elementary school children who returned from an extended school closure caused by the Covid-19 pandemic relative to proximate pre-pandemic cohorts. This developmental delay has a significant socioeconomic gradient, with underprivileged children experiencing more substantial delays. We also document a significant disruption in the development of socioemotional skills: 0.24 sd lower grit, 0.43 sd lower emotional empathy, 0.06 sd lower epistemic curiosity, and 0.24 sd higher impulsivity. About eight months of school exposure results in a remarkable recovery in abstract reasoning and theory of mind for all socioeconomic groups. However, the measured levels still indicate significant delays relative to the expected developmental trajectories. No notable improvements are observed in socioemotional skills except for curiosity. These findings reveal that the damage school closures inflicted on children goes beyond well-documented academic losses and highlight the crucial role of the school environment in fostering fundamental cognition and socioemotional development in children.
Mots clés Abstract reasoning, Cognitive empathy, Socioemotional skills, Schoolclosures
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