L'impact d'exonérations fiscales sur la création d'établissements et l'emploi en France rurale : une approche par discontinuité de la régression

Since 1996 the French rural development policy has defined Rural Revitalization Zones (ZRR) in which the enterprises of less than 50 employees are eligible for tax exemptions. The fiscal exemptions are of great scale in the ZRR (30% of gross salary for the wages below 1.5 minimum wage) and they potentially apply to 10.7% of below 50 employees enterprises. Until now, the impact of the device on the economy has only be analysed in descriptive studies. In this paper, a measure of the causal impact of the exemptions in ZRR is suggested. A feature in the implementation of the device allows to use a well known econometric method in the evaluation of public policies. The enterprises located in the ZRR are the only one which can benefit from the exemptions. Moreover these zones have been defined using precise population density and demographics criteria. A Regression Discontinuity Design is therefore well suited to the evaluation the policy. It allows disentangling the impact of the ZRR implementation on firm and jobs creation from the background characteristics in the ZRR. Our results show that the tax exemptions neither have any significant impact on employment nor on firms creation in disadvantaged rural zones.A partir de 1996, la politique de développement rural française définit des zones de revitalisation rurale (ZRR) : les entreprises de moins de 50 salariés peuvent y bénéficier d'exonérations de charges à condition (entre autres) d'augmenter leur effectif salarié. Ces zones regroupent des territoires ruraux en difficultés : faible densité démographique, handicap structurel sur le plan socio-économique. Les exonérations fiscales en ZRR sont de grande ampleur (30 % du salaire brut pour des salaires compris entre 1 et 1,5 fois le Smic) et concernent potentiellement une part non négligeable des entreprises puisque 10,7 % de celles de moins de 50 salariés y sont situées. Jusqu'à présent, l'effet du dispositif sur l'économie a essentiellement été l'objet d'études descriptives. Seule l'analyse de Lofredi (2007) tente de mettre en évidence l'effet causal de la mise en place de la mesure sur l'emploi et la création d'établissements. Une particularité du dispositif permet de tester l'effet causal des exonérations en ZRR en s'appuyant sur une méthode désormais largement utilisée pour étudier l'effet de politiques publiques. Il s'agit de remarquer que les ZRR ont été définies à partir de critères précis de densité et de démographie et que seules les entreprises situées en ZRR sont éligibles aux exonérations de charges. Une approche par "discontinuité de la régression" permet alors de dissocier l'effet de la mesure sur l'emploi et la création d'entreprises du rôle des caractéristiques propres aux ZRR. Les résultats tendent à confirmer les conclusions de Lofredi (2007) à partir d'une méthode différente. Ce dispositif d'exonération fiscale n'aurait d'effet significatif ni sur l emploi, ni sur la création d'établissements dans les zones rurales défavorisées. L'existence de restrictions fortes quant à l'accès aux exonérations pour les entreprises ainsi que la particularité du contexte rural dans lequel la mesure a été mise en place pourraient expliquer l'échec de la mesure

Capillary imbibition of aqueous foams by miscible and nonmiscible liquids

International audienceWhen put in contact with a large liquid drop, dry foams wick owing to surface-tension-driven flows until reaching equilibrium. This work is devoted to the dynamics of this imbibition process. We both consider imbibition of wetting or non-wetting liquid, either by putting the dry foam into contact with the foaming solution that constitutes the foam or with organic oils. Indeed, with the appropriate choice of surfactants, oil spontaneously invades the liquid network of the foam without damaging it. Our experiments show an early-time dynamics in t 1/2 followed by a late-time dynamics in t 1/4. These features, which differ from theoretical works predicting a late-time t 1/3 dynamics, are rationalized considering the influence of the initial liquid fraction of the foam in the driving capillary force and the impact of gravity through the capillary-gravity equilibrium

Student loans: Liquidity constraint and higher education in South Africa

Empirical evidence that access to higher education is constrained by credit availability is limited and usually indirect. This paper provides direct evidence by comparing university enrollment rates of South African potential students, depending on whether they get a loan or not to cover their registration fees, in a context where such fees are high. We use matched individual data from both a credit institution (Eduloan) and the Department of Education. Based on a regression discontinuity design using the fact that loans are granted according to a credit score threshold, we can estimate the causal impact of loan obtainment. We find that the credit constraint is substantial, as it decreases the enrollment rate into higher education by more than 20 percentage points in a population of student loan applicants.Il est difficile de démontrer que les contraintes de crédit sont un frein à l'accès à l'enseignement supérieur : les preuves sont rares et toujours indirectes. Cet article propose une mesure directe de la contrainte de crédit en comparant l'accès à l'université d'étudiants potentiels en Afrique du Sud, selon qu'ils ont accès ou non à un prêt pour couvrir leur frais d'inscription, dans un contexte où ces frais sont élevés. Nous utilisons des données individuelles qui apparient des fichiers d'une institution de crédit aux étudiants (Eduloan) et les fichiers du ministère de l'éducation. L'identification de l'effet d'un prêt sur l'inscription à l'université repose sur la méthode de régression de la discontinuité : on utilise le fait que les prêts sont accordés sur la base d'une valeur seuil d'un score d'historique de crédit. Nous trouvons que les contraintes de crédit sont importantes, puisqu'elles réduisent le taux d'entrée à l'université dans plus de 20 points, dans notre population de candidats à un prêt

La population migrante de Bâle entre 1870 et 1920

Le but de cet article est de présenter succinctement quelques-unes des sources permettant d’étudier la population migrante arrivant – et, pour une partie d’entre elle, se fixant – dans la ville de Bâle (Suisse alémanique) entre 1870 et 1920. J’essayerai de montrer quelles possibilités d’exploitation ces sources permettent d’envisager. Quelques exemples concrets étayeront les considérations théoriques. L’un des éléments que l’histoire urbaine cerne avec le plus de difficultés lorsqu’elle abord..

On the stability of the production of bubbles in yield-stress fluid using flow-focusing and T-junction devices

International audienceWe investigate experimentally the stability of bubble production in yield-stress fluids (YSF) and highly viscous silicone oil, using flow-focusing and T-junction devices. When the exit channel is initially pre-filled with the fluid and the gas is pressure-driven, the production is highly unstable, despite a regular frequency of bubble production in the junction. As observed for pressure-driven bubble trains in Newtonian fluids, we report that two mechanisms can explain these observations : (i) drastic reduction of the hydrodynamic pressure drop along the channel during the transient bubble production, which induces a rapid increase of the gas flow rate and (ii) thin film deposition resulting in a cascade of plug break-up and bubbles coalescence. While the drastic reduction of the pressure drop is inevitable in such two-phase flows, we show that modifying the surfaces of the channel can help stabilizing the system when the continuous phase is a YSF. To do so, we measure the thickness of the film deposited on the channel wall for rough and smooth channels. Our results are rationalized by introducing the inverse of the Bingham number Bi −1 comparing the viscous stress to the yield stress. For Bi −1 ≥ 1, a fast fluidization process associated to efficient deposition of YSF on the channel wall leads to a rapid destabilization of the bubble production. However, for Bi −1 < 1, the deposition driven by capillarity can be hindered by the wall-slip induced by the existence of the yield stress: the thickness of the deposited film is very thin and corresponds to the equivalent roughness of the channels. It is typically 40 µm thick for rough surfaces and below the limit of resolution of our setup for smooth surfaces. In this regime of Bi −1 and for smooth surfaces, the length of the plugs barely vanishes, thus the start-up flow is less prone to destabilization. These results therefore potentially open routes to steady production of aerated YSF on smooth channels in the regime of small Bi −1

Bubble Formation in Yield Stress Fluids Using Flow-Focusing and T-Junction Devices

International audienceWe study the production of bubbles inside yield stress fluids (YSFs) in axisymmetric T-junction and flow-focusing devices. Taking advantage of yield stress over capillary stress, we exhibit a robust break-up mechanism reminiscent of the geometrical operating regime in 2D flow-focusing devices for Newtonian fluids. We report that when the gas is pressure driven, the dynamics is unsteady due to hydrodynamic feedback and YSF deposition on the walls of the channels. However, the present study also identifies pathways for potential steady-state production of bubbly YSFs at large scale

Writer recognition in cursive eye writing: a Bayesian model

International audienceUsing a novel apparatus coupling a visual illusion with an eye tracker device, trained participants are able to generate smooth pursuit eye movements, even without a target to follow. This allows them to perform arbitrary continuous shapes, and, for instance, write letters with their eyes. In a previous study, based on data from a single writer (author JL), we developed and tested a Bayesian computational model -- the BAP-EOL model -- able to simulate character recognition. In the present study, data from different writers provide the opportunity to study the signal characteristics of eye-written letters. More precisely, we extend the model to perform writer recognition. Experimental results, and high performance we obtained, show that eye writing is as writer specific as handwriting is, and that motor idiosyncrasies are present in eye-written letters