Essays in applied microeconomics

This dissertation contains three chapters. The first chapter examines job training programmes for job-seekers, a major policy tool governments use to reduce unemployment. I study the effects of increasing the financial support offered to possibly credit-constrained trainees. Using a triple difference approach, I find that increasing the training grant amount for trainees leads to more training entries. However, this also increases the number of hours missed from training, suggesting that newly added trainees are choosing part-time work over training attendance. Smoothing the disbursement schedule of the grant improves the attendance rate. I also look for evidence of credit constraints in the estimated returns to training, but the results are inconclusive. The second chapter, joint with Laura Castell, Cl´ement Imbert and Marc Gurgand, studies barriers to the take-up of social benefits in France using a nationwide experiment that invited job seekers to a meeting with social services to discuss eligibility and provide application assistance. Eligible individuals do not apply: attending the meeting increased new benefits by 31%. We investigate the relative importance of transaction costs, incomplete information and social stigma using experimental variation in invitation letter phrasing and encouragement to use a personalised online eligibility simulator. The evidence points to transaction costs as the main take-up barrier. Estimated marginal treatment effects show that individuals who benefit the most from take-up assistance are the least likely to attend the meeting. The third chapter, joint with Gabriele Guaitoli, examines the labour market spillovers associated with business restrictions imposed by counties in the US during the Covid-19 pandemic. We exploit the U.S. local variation in restrictions and commuting and estimate the causal direct and mobility spillover impacts of lockdowns. Mobility spillovers alone account for 10-15% of U.S. job losses at peak. We corroborate these results with causal evidence for a consumption-based mechanism: shops whose clients reside in higher proportion in neighbouring areas under lockdown experience larger employment losses. Not accounting for mobility spillovers leads to overestimating direct lockdown effects but underestimating total ones. xii

The Alzheimer's disease amyloid-β peptide affects the size-dynamics of raft-mimicking Lo domains in GM1-containing lipid bilayers

International audience† Electronic supplementary information (ESI) available: Films illustrating the effect of A(1-42) on photoinduced spinodal decomposition in GUVs, speed acceletated x 12: Movie_1_GUVs_PC-SM-Chol_10%GM1_withoutAb_20Cx12.avi Movie_2_GUVs_PC-SM-Chol_10%GM1_withAb_20Cx12.avi, Movie_3_GUVs_PC-SM-Chol_10%GM1_withoutAb_14Cx12.avi Movie_4_GUVs_PC-SM-Chol_10%GM1_withAb_14Cx12.avi Alzheimer's disease (AD) is characterized by the overproduction of the amyloid- peptide (A) which forms fibrils under the influence of raft microdomains containing the ganglioside GM1. Raft-mimicking artificial liquid ordered (Lo) domains containing GM1 enhance amyloid- polymerization. Other experiments suggest that A binds preferably to the non-raft liquid disordered (Ld) phase rather than to the Lo phase in the presence of GM1. Here, the interaction of A(1-42) with GM1-containing biphasic Lo-Ld giant vesicles was investigated. Fluorescence colocalisation experiments confirm that A(1-42) binds preferentially to the Ld phase. The effect of A(1-42) on Lo-Ld size dynamics was studied using photoinduced spinodal decomposition which mimics the nanodomain-microdomain raft coalescence. A affects the kinetics of the coarsening phase and the size of the resulting microdomains. The effect depends on which phase is majoritary: when Lo microdomains are formed inside an Ld phase, their growth rate becomes slower and their final size smaller in the presence of A(1-42), whereas when Ld microdomains are formed inside an Lo phase, growth rate becomes faster and final size larger. Fluorimetric measurements on large vesicles using the probe LAURDAN indicate that A(1-42) binding respectively increases or decreases the packing of the Ld phase in the presence or absence of GM1. The differential effects of A on spinodal decomposition are accordingly interpreted as resulting from distinct effects of the peptide on Lo-Ld line tension modulated by GM1. Such modulating effect of A on domain dynamics could be important for lipid rafts in signaling disorders in AD as well as in A fibrillation