Essays in empirical labor, housing and social network economics

Cette thèse explore les deux sujets suivants: (i) les déterminants de la participation à la population active des personnes âgées aux États-Unis; (ii) le rôle du réseau social dans le niveau de revenus de travail des immigrants récents au Canada. Plus précisément, le chapitre 1 utilise les données du Health and Retirement Study (HRS) pour fournir des estimations de l’effet causal du prix des maisons au niveau local sur les décisions d’offre de travail des individus âgés aux États-Unis, au cours de la période du boom immobilier 1994- 2004. Le prix des maisons est instrumentalisé par des variations spatiales et temporelles de chocs plausiblement exogènes de l’offre de crédit. Les estimations suggèrent que le boom immobilier durant la période considérée pourrait expliquer jusqu’à deux tiers des sorties de la population active des hommes âgés aux États-Unis. Le chapitre 2 répond à la question: les personnes en bonne santé sont-elles plus susceptibles de rester sur le marché du travail lorsque le chômage augmente? Ce travail fournit des estimations empiriques de l’impact relatif des chocs de chômage au niveau local sur la participation au marché du travail des américains âgés ayant des états de santé hétérogènes. Cette étude montre que la plupart des départs de travailleurs âgés pendant la Grande récession peuvent être attribués à de mauvaises conditions de santé, telles que mesurées, avant la récession. Enfin, le chapitre 3 analyse l’effet du fait de vivre dans un quartier où la majorité des résidents appartient à des minorités visibles sur les gains des résidents permanents qui sont arrivés à Montréal, Vancouver et Toronto en 2001. Dans l’ensemble, cette recherche documente un effet négatif du regroupement ethnique sur les gains des immigrants récents au Canada et l’explique par "l’effet d’aiguillage".This thesis explores the following two topics : (i) determinants of labor force participation at older ages in the US ; (ii) the role of social network in the earnings of recent immigrants in Canada. Specifically, Chapter 1 provides estimates of the causal effect of local house prices on the labor supply decisions of older workers in the US during the 1994-2004 housing boom period using data from the Health and Retirement Study (HRS). Local house prices are instrumented by plausible exogenous spatial and time-varying credit supply shocks. The estimates suggest that the housing boom accounted for about two thirds of older men labor force exit during the studied period. Chapter 2 responds to the question : are people in good health more likely to stay in the labor market when unemployment rises? This work provides empirical estimates of the relative impact of local unemployment shocks on the labor force participation of US older workers with heterogeneous health conditions. This study documents that most of the labor force exit of older workers during the Great recession can be attributed to poor health conditions measured before the recession. Finally, Chapter 3 analyses the effect of living in a neighborhood where the majority of the residents belongs to visible minority groups on the earnings of permanent residents who landed in Montreal, Vancouver and Toronto in 2001. Overall, this research documents a negative effect of ethnic clustering on the earnings of recent immigrants in Canada and explain it by the "referral effect"

A low-cost fluorescence reader for in vitro transcription and nucleic acid detection with Cas13a

Point-of-care testing (POCT) in low-resource settings requires tools that can operate independently of typical laboratory infrastructure. Due to its favorable signal-to-background ratio, a wide variety of biomedical tests utilize fluorescence as a readout. However, fluorescence techniques often require expensive or complex instrumentation and can be difficult to adapt for POCT. To address this issue, we developed a pocket-sized fluorescence detector costing less than $15 that is easy to manufacture and can operate in low-resource settings. It is built from standard electronic components, including an LED and a light dependent resistor, filter foils and 3D printed parts, and reliably reaches a lower limit of detection (LOD) of. 6.8 nM fluorescein, which is sufficient to follow typical biochemical reactions used in POCT applications. All assays are conducted on filter paper, which allows for a flat detector architecture to improve signal collection. We validate the device by quantifying in vitro RNA transcription and also demonstrate sequence-specific detection of target RNAs with an LOD of 3.7 nM using a Cas13a-based fluorescence assay. Cas13a is an RNA-guided, RNA-targeting CRISPR effector with promiscuous RNase activity upon recognition of its RNA target. Cas13a sensing is highly specific and adaptable and in combination with our detector represents a promising approach for nucleic acid POCT. Furthermore, our open-source device may be used in educational settings, through providing low cost instrumentation for quantitative assays or as a platform to integrate hardware, software and biochemistry concepts in the future

Caractérisation du charbonnage moderne et contemporain bisontin (Franche-Comté, France) et de son impact sur les peuplements forestiers : le cas de la forêt de Chailluz

The Franche-Comté forest, in particular the forest of Besançon, suffered heavily from its exploitation during the 18th and 19th centuries, causing a wood shortage in the territory. In many historiographical sources and research, the reasons of this shortage appear to be complex and manifold. The discovery of nearly a thousand charcoal platforms in the Chailluz forest has led to a series of questions concerning the function of this forest and the role of charcoal production in the wood shortage. The first fruits of an archival study made it possible to identify and characterize the major consumers of wood in the territory of Besançon during the 18th and 19th centuries other than the charcoal production, because rarely mentioned in the literature. The archaeometric study of the Chailluz charcoal platforms made it possible to characterize the charcoal production at the end of the modern age, providing the image of the 18th century forest stands and the impact of this practice on Chailluz.La forêt franc-comtoise, en particulier la forêt bisontine, a lourdement souffert de son exploitation au cours des XVIIIème et XIXème siècles, entrainant une pénurie de bois sur le territoire bisontin. Dans de nombreuses sources historiographiques et travaux de recherche, les raisons de cette pénurie apparaissent comme étant complexes et multiples. La découverte de près d'un millier de plateformes de charbonnage en forêt de Chailluz a induit toute une série de questionnements concernant la fonction de cette forêt et le rôle du charbonnage dans la pénurie de bois bisontine. Les prémices d’une étude archivistique ont permis d’identifier et de caractériser les grands consommateurs du bois du territoire bisontin durant les XVIIIème et XIXème siècles autres que l’activité charbonnière, puisque très rarement citée dans les textes. L’étude archéométrique des plateformes de la forêt de Chailluz a permis de caractériser le charbonnage de la fin de l’époque moderne, fournissant alors l’image des peuplements forestiers du XVIIIème siècle ainsi que l’impact de cette pratique sur cette forêt

Characterization of the charcoal production of the territory of Besançon during the modern and contemporary periods (Franche-Comté, France) and its impact on the forest stands : the case of the Chailluz forest

La forêt franc-comtoise, en particulier la forêt bisontine, a lourdement souffert de son exploitation au cours des XVIIIème et XIXème siècles, entrainant une pénurie de bois sur le territoire bisontin. Dans de nombreuses sources historiographiques et travaux de recherche, les raisons de cette pénurie apparaissent comme étant complexes et multiples. La découverte de près d'un millier de plateformes de charbonnage en forêt de Chailluz a induit toute une série de questionnements concernant la fonction de cette forêt et le rôle du charbonnage dans la pénurie de bois bisontine. Les prémices d’une étude archivistique ont permis d’identifier et de caractériser les grands consommateurs du bois du territoire bisontin durant les XVIIIème et XIXème siècles autres que l’activité charbonnière, puisque très rarement citée dans les textes. L’étude archéométrique des plateformes de la forêt de Chailluz a permis de caractériser le charbonnage de la fin de l’époque moderne, fournissant alors l’image des peuplements forestiers du XVIIIème siècle ainsi que l’impact de cette pratique sur cette forêt.The Franche-Comté forest, in particular the forest of Besançon, suffered heavily from its exploitation during the 18th and 19th centuries, causing a wood shortage in the territory. In many historiographical sources and research, the reasons of this shortage appear to be complex and manifold. The discovery of nearly a thousand charcoal platforms in the Chailluz forest has led to a series of questions concerning the function of this forest and the role of charcoal production in the wood shortage. The first fruits of an archival study made it possible to identify and characterize the major consumers of wood in the territory of Besançon during the 18th and 19th centuries other than the charcoal production, because rarely mentioned in the literature. The archaeometric study of the Chailluz charcoal platforms made it possible to characterize the charcoal production at the end of the modern age, providing the image of the 18th century forest stands and the impact of this practice on Chailluz

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Contribution of tyloses quantification in earlywood oak vessels to archaeological charcoal analyses: Estimation of a minimum age and influences of physiological and environmental factors

International audienceAmong the main parameters contributing to the characterization of firewood exploitation modes, the age of the collected wood is very difficult to assess in anthracology. In this paper, we propose an original way to investigate the age of the exploited wood, the heartwood formation process which takes place in 20 e25-year-old deciduous oak trees. The formation of tyloses in earlywood vessels is an important feature of the changeover of sapwood to heartwood. However, tylosis formation also occurs in sapwood. Therefore, the observation of the mere presence of tyloses in vessels, as routinely performed in anthracology, is not sufficient to distinguish sapwood from heartwood. The aim of this study was thus to use the proportion of vessels sealed by tyloses as a discriminating marker between sapwood and heartwood applicable to anthracology in order to characterize firewood exploitation in the past. The trunks and branches of ten deciduous oak trees ranging from 15 to 60 years old were sampled in three French sites. For an application to archaeological charcoal (tyloses are preserved until 800 C), thresholds of less than 65% for sapwood and up to 85% for heartwood appear to be significant at the population level for deciduous oak (Quercus petraea/robur) in a temperate climate. Besides the indication of the minimal age (ca. 25 years old in the case of deciduous oak), the variability of the proportion of vessels with tyloses in sapwood is explored as a good indicator of the vitality of the wood which opens new prospects for the exploitation of dendro-anthracological parameters, such as the discrimination of branch wood

The taphonomic characterization of a charcoal production platform. Contribution of an innovative pair of methods: Raman analysis and micromorphology

International audienceDuring the Industrial Revolution and until the 19th century, the fuel used in metallurgy was charcoal. The frequent charcoal-making places identified in European archaeological sites are one of the only direct markers of this activity. Understanding the soil stratigraphy of these locations enables us to characterize the intensity of charcoal production and especially to grasp an insight into the forest management of the studied site during charcoal making. Two types of soil profiles have been observed in Europe. The first presents one or several sterile horizons identifiable with the naked eye, separating charcoal levels. The second, which is the most commonly observed type at European archaeological sites, is characterized by a single charcoal level of variable thickness. For the present study, located in eastern France (Franche-Comté), we propose to characterize the soil profile of a charcoal platform, which looks like the second type observed at the European scale, through the application of an innovative pair of methods: The Raman analysis and micromorphology. The Raman paleothermometer, defined by Deldicque et at. (2016) was adapted to define the temperatures reached in charcoal-making contexts. These measurements agree with the literature and experiments. These temperatures are regularly distributed over the profile, confirming the reuse of the platform. Similarly, the micromorphology of the soil profile reveals clear indicators of reuse, with no evidence of long interruptions in charcoal making

Le marquis de Villemer : comédie en quatre actes.

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