Publications

La plupart des informations présentées ci-dessous ont été récupérées via RePEc avec l'aimable autorisation de Christian Zimmermann
Vector Optimization with Domination Structures: Variational Principles and ApplicationsJournal articleTruong Q. Bao, Boris S. Mordukhovich, Antoine Soubeyran et Christiane Tammer, Set-Valued and Variational Analysis, Forthcoming

This paper addresses a large class of vector optimization problems in infinite-dimensional spaces with respect to two important binary relations derived from domination structures. Motivated by theoretical challenges as well as by applications to some models in behavioral sciences, we establish new variational principles that can be viewed as far-going extensions of the Ekeland variational principle to cover domination vector settings. Our approach combines advantages of both primal and dual techniques in variational analysis with providing useful sufficient conditions for the existence of variational traps in behavioral science models with variable domination structures.

An evolutionary finance model with short selling and endogenous asset supplyJournal articleRabah Amir, Sergei Belkov, Igor V. Evstigneev et Thorsten Hens, Economic Theory, Forthcoming

Evolutionary finance focuses on questions of “survival and extinction” of investment strategies (portfolio rules) in the market selection process. It analyzes stochastic dynamics of financial markets in which asset prices are determined endogenously by a short-run equilibrium between supply and demand. Equilibrium is formed in each time period in the course of interaction of portfolio rules of competing market participants. A comprehensive theory of evolutionary dynamics of this kind has been developed for models in which short selling is not allowed and asset supply is exogenous. The present paper extends the theory to a class of models with short selling and endogenous asset supply.

A new regularization of equilibrium problems on Hadamard manifolds. Applications to theories of desiresJournal articleG. C. Bento, J.X. Cruz Neto, Jr. P. A. Soares et Antoine Soubeyran, Annals of Operations Research, Forthcoming

In this paper, we introduce a new proximal algorithm for equilibrium problems on a genuine Hadamard manifold, using a new regularization term. We first extend recent existence results by considering pseudomonotone bifunctions and a weaker sufficient condition than the coercivity assumption. Then, we consider the convergence of this proximal-like algorithm which can be applied to genuinely Hadamard manifolds and not only to specific ones, as in the recent literature. A striking point is that our new regularization term have a clear interpretation in a recent “variational rationality” approach of human behavior. It represents the resistance to change aspects of such human dynamics driven by motivation to change aspects. This allows us to give an application to the theories of desires, showing how an agent must escape to a succession of temporary traps to be able to reach, at the end, his desires.

Health effects from heat waves in France: an economic evaluationJournal articleLucie Adélaïde, Olivier Chanel et Mathilde Pascal, The European Journal of Health Economics, Forthcoming

Background :
Scarcity of data on the health impacts and associated economic costs of heat waves may limit the will to invest in adaptation measures. We assessed the economic impact associated with mortality, morbidity, and loss of well-being during heat waves in France between 2015 and 2019.

Methods :
Health indicators monitored by the French national heat wave plan were used to estimate excess visits to emergency rooms and outpatient clinics and hospitalizations for heat-related causes. Total excess mortality and years of life loss were considered, as well as the size of the population that experienced restricted activity. A cost-of-illness and willingness-to-pay approach was used to account for associated costs.

Results :
Between 2015 and 2019, the economic impact of selected health effects of heat waves amounts to €25.5 billion, mainly in mortality (€23.2 billion), minor restricted activity days (€2.3 billion), and morbidity (€0.031 billion).

Conclusion :
The results highlight a significant economic burden on the French health system and the population. A better understanding of the economic impacts of climate change on health is required to alert decision-makers to the urgency of mitigation and to support concrete adaptation actions.

Getting used to terrorist threats? Evidence from French terrorist attacks between 2015 and 2016Journal articleSylvie Blasco, Eva Moreno-Galbis et Jérémy Tanguy, Health Economics, Volume n/a, Issue n/a, Forthcoming

This paper evaluates the effect on mental health of consecutive terrorist attacks in France in 2015 and 2016. We compile information about the three main terrorist attacks that struck France over this period and assess whether the potential effect on mental health (i.e., depression) of a terrorist attack is smoothed once people consider terrorist attacks as “the new normality.” We exploit data from the French Constances epidemiological survey and combine an event study strategy with a difference-in-difference approach to compare before-after changes in mental health the year of the attack with the same changes the year before. We show that the negative effect of a terrorist attack on mental health decreases over time from one attack to another, and disappears completely for the last attack. Socio-demographic composition of the sample, geographical or socio-demographic proximity to the victims or media exposure do not arise as factors responsible for this changing effect of terrorist attacks on mental health.

Variational rationality, variational principles and the existence of traps in a changing environmentJournal articleMajid Fakhar, Mohammadreza Khodakhah, Ali Mazyaki, Antoine Soubeyran et Jafar Zafarani, Journal of Global Optimization, Forthcoming

This paper has two aspects. Mathematically, in the context of global optimization, it provides the existence of an optimum of a perturbed optimization problem that generalizes the celebrated Ekeland variational principle and equivalent formulations (Caristi, Takahashi), whenever the perturbations need not satisfy the triangle inequality. Behaviorally, it is a continuation of the recent variational rationality approach of stay (stop) and change (go) human dynamics. It gives sufficient conditions for the existence of traps in a changing environment. In this way it emphasizes even more the striking correspondence between variational analysis in mathematics and variational rationality in psychology and behavioral sciences.

Roots of Gender Equality : the Persistent Effect of Beguinages on Attitudes Toward WomenJournal articleÈric Roca Fernández et Annalisa Frigo, Journal of Economic Growth, Forthcoming

This paper is concerned with the historical roots of gender equality. It proposes and empirically assesses a new determinant of gender equality: gender-specific outside options in the marriage market. In particular, enlarging women’s options besides marriage—even if only temporarily—increases their bargaining power with respect to men, leading to a persistent improvement in gender equality. We illustrate this mechanism focusing on Belgium, and relate gender-equality levels in the 19th century to the presence of medieval, female-only communities called beguinages that allowed women to remain single amidst a society that traditionally advocated marriage. Combining geo-referenced data on beguinal communities with 19th-century census data, we document that the presence of beguinages contributed to decrease the gender gap in literacy. The reduction is sizeable, amounting to a 12.3% drop in gender educational inequality. Further evidence of the beguinal legacy is provided leveraging alternative indicators of female agency.

Gender Identity and Quality of EmploymentJournal articleEstefanía Galván, Economica, Volume n/a, Issue n/a, Forthcoming

Studies for high-income countries have shown that the prescription that a man should earn more than his wife holds back women's performance in the labour market, evidencing the importance of gender identity norms in explaining persistent gender gaps. Using data on couples in Uruguay for the period 1986–2016, this paper analyses behavioural responses to the male breadwinner norm, investigating the role of job informality as an additional mechanism of response to gender norms. My results show that the higher the probability that the wife earns more than her husband, the less likely she is to engage in a formal job, providing evidence that gender norms affect not only the quantity of labour supply (i.e. labour force participation and hours of work), but also the quality of jobs in which women are employed. Moreover, I also identify meaningful effects of the norm on men: those with lower potential earnings than their wives react to the norm by self-selecting into better-paid formal jobs. Not considering these effects would lead to underestimating the consequences of gender norms on labour market inequalities in the context of developing countries.

Asymmetric Information and Differentiated Durable Goods Monopoly: Intra-Period Versus Intertemporal DiscriminationJournal articleDidier Laussel, Ngo Van Long et Joana Resende, Dynamic Games and Applications, Forthcoming

A durable good monopolist faces a continuum of heterogeneous customers who make purchase decisions by comparing present and expected price-quality offers. The monopolist designs a sequence of price-quality menus to segment the market. We consider the Markov perfect equilibrium (MPE) of a game where the monopolist is unable to commit to future price-quality menus. We obtain the novel results that: (a) under certain conditions, the monopolist covers the whole market in the first period (even when a static Mussa–Rosen monopolist would not cover the whole market), because this is a strategic means to convince customers that lower prices would not be offered in future periods and that (b) this can happen only under the stage-wise Stackelberg leadership assumption (whereby consumers base their expectations on the value of the state variable at the end of the period). Conditions under which MPE necessarily involves sequentially trading are also derived.

Hepatitis B in Senegal: A Successful Infant Vaccination Program but Urgent Need to Scale Up Screening and Treatment (ANRS 12356 AmBASS survey)Journal articleLauren Perieres, Aldiouma Diallo, Fabienne Marcellin, Marie Libérée Nishimwe, El Hadji Ba, Marion Coste, Gora Lo, Philippe Halfon, Coumba Toure Kane, Gwenaelle Maradan, et al., Hepatology Communications, pp. hep4.1879, Forthcoming

Senegal introduced the infant hepatitis B virus (HBV) vaccination in 2004 and recently committed to eliminating hepatitis B by 2030. Updated epidemiological data are needed to provide information on the progress being made and to develop new interventions. We estimated the prevalence of hepatitis B surface antigen (HBsAg) in children and adults living in rural Senegal and assessed hepatitis B treatment eligibility. A cross-sectional population-based serosurvey of HBsAg was conducted in 2018-2019 in a large sample (n = 3,118) of residents living in the Niakhar area (Fatick region, Senegal). Individuals positive for HBsAg subsequently underwent clinical and biological assessments. Data were weighted for age and sex and calibrated to be representative of the area's population. Among the 3,118 participants, 206 were HBsAg positive (prevalence, 6.9%; 95% confidence interval [CI], 5.6-8.1). Prevalence varied markedly according to age group in individuals aged 0-4, 5-14, 15-34, and >= 35 years as follows: 0.0% (95% CI, 0.00-0.01); 1.5% (95% CI, 0.0-2.3); 12.4% (95% CI, 9.1-15.6); and 8.8% (95% CI, 6.1-11.5), respectively. Of those subsequently assessed, 50.9% (95% CI, 41.8-60.0) had active HBV infection; 4 (2.9%; 95% CI, 0.9-9.4) were eligible for hepatitis B treatment. Conclusion: In this first population-based serosurvey targeting children and adults in rural Senegal, HBsAg prevalence was very low in the former, meeting the World Health Organization's (WHO) < 1% HBsAg 2020 target; however, it was high in young adults (15-34 years old) born before the HBV vaccine was introduced in 2004. To reach national and WHO hepatitis elimination goals, general population testing (particularly for adolescents and young adults), care, and treatment scale-up need to be implemented.