TRITAH Ahmed

This thesis aims to highlight the potential of information and communication technologies (ICTs), and specifically cell phones, in sub-Saharan Africa to improve household livelihoods through information dissemination, rent redistribution and financial inclusion. Africa is the least developed continent, which suffers from poverty, lack of essential infrastructure, famine problems, the highest rates of illiteracy and limited access to financial services. Furthermore, international organizations such as the World Bank believe that the expansion of cell phone adoption represents an opportunity to overcome some of these barriers through innovative uses in the rural world which suffers more from these physical barriers. Through this thesis we evaluate the impact of the use of its services via cell phone in the agricultural sector, in order to draw conclusions on their benefits and quantify them, to enlighten the public authorities, private and non-governmental organizations on their real contributions and direct them towards services adapted to the needs of the population.

Over the period 1994-2012, immigrants' wage growth in France has outperformed that of natives on average by more than 14 percentage points. This striking wage growth performance occurs despite similar changes in employment shares along the occupational wage ladder. In this paper we investigate the sources of immigrants' relative wage performance focusing on the role of occupational tasks. We rst show that immigrants' higher wage growth is not driven by more favorable changes in general skills (measured by age, education and residence duration), and then investigate to what extent changes in task-speci c returns to skills have contributed to the differential wage dynamics through two different channels: different changes in the valuation of skills (\price effect") and different occupational sorting (\quantity effect"). We nd that the wage growth premium of immigrants is not explained by different changes in returns to skills across occupational tasks but rather by the progressive reallocation of immigrants towards tasks whose returns have increased over time. Immigrants seem to have taken advantage of ongoing labor demand restructuring driven by globalization and technological change. In addition immigrants' wages have been relatively more affected by minimum wage increases, due to their higher concentration in this part of the wage distribution.

Over the period 1994–2012, immigrants’ wage growth in France outperformed that of natives. We investigate to what extent changes in task-specific returns to skills contributed to this wage dynamics differential through two channels: changes in the valuation of skills (price effect) and occupational sorting (quantity effect). We find that the wage growth premium of immigrants is mainly explained by the progressive reallocation of immigrants toward tasks whose returns increase over time. Immigrants seem to have taken advantage of labor demand restructuring driven by globalization and technological changes.

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Over the period 1994-2012, immigrants’ wage growth in France has outperformed that of natives on average by more than 14 percentage points. This striking wage growth performance occurs despite similar changes in employment shares along the occupational wage ladder. In this paper we investigate the sources of immigrants’ relative wage performance focusing on the role of occupational tasks. We first show that immigrants’ higher wage growth is not driven by more favorable changes in general skills (measured by age, education and residence duration), and then investigate to what extent changes in task-specific returns to skills have contributed to the differential wage dynamics through two different channels: different changes in the valuation of skills (“price effect”) and different occupational sorting (“quantity effect”). We find that the wage growth premium of immigrants is not explained by different changes in returns to skills across occupational tasks but rather by the progressive reallocation of immigrants towards tasks whose returns have increased over time. Immigrants seem to have taken advantage of ongoing labor demand restructuring driven by globalization and technological change. In addition im- migrants’ wages have been relatively more affected by minimum wage increases, due to their higher concentration in this part of the wage distribution.

No summary available.

This thesis examines the sustainable management of non-renewable resources in general and rock phosphate in particular. The first chapter outlines the status, prospects and economic and geopolitical issues of the world phosphate market. This analysis highlights a significant long-term deficit in world supply compared to demand, encouraging phosphate producers, who have sufficient reserves, to invest in new capacities. The second chapter develops a multi-player Stackelberg model, calibrated on actual phosphate market data, and allows the calculation of the optimal capacities to be put in place by producers according to their reserve levels and development costs. The results of this model show that the market would become more concentrated in 2100 than it is today, with Morocco, the country that holds three quarters of the world's reserves, dominating. The third chapter aims to assess the spillover effects that Morocco generates from its phosphate exploitation. Using the Input-Output model, the proposed empirical analysis compares the socio-economic impacts of extraction with those of beneficiation or processing. The results of this analysis show that phosphate processing is more connected upstream with other branches of the economy and generates more value added, income and employment. The last chapter attempts to address the issue of the natural resource curse in a new way by linking agricultural performance and urbanization to the abundance of these resources. The empirical study, based on a panel of African countries, shows a significant link between the abundance of mineral resources, the underdevelopment of the agricultural sector and the urban explosion.

Immigrants are new comers in a labor market. As a consequence, they lack of social networks and other country specific and not directly productive valuable assets affecting their relative bargaining position against employers. We introduce this simple observation into a matching model of the labor market and show that immigrants increase employment prospects of competing natives. To test the predictions of our model, we exploit yearly vari- ations between 1998 and 2004 in the share of immigrants within occupations of 12 European countries. We identify the causal impact of immigrants on natives’ employment rate using an instrumental variable strategy based on historical settlement patterns across host countries and occupations by origin countries. We find that natives’ employment rate increases in oc- cupations and sectors receiving more immigrants. Moreover, we highlight the heterogeneity of this impact across groups of immigrants and host countries along dimensions that affect immigrants-natives relative reservation wages.