Дисертації з теми "Fertility transfer"

Background and aims: Assisted reproductive technology has provided great hope for millions of infertile couples. In recent years, frozen-thawed embryo transfer has no longer been merely an add-on to the conventional fresh embryo transfer. Transfer of a cryopreserved embryo has contributed to nearly half of the embryo transfer cycles in Australia. The aim of this thesis is to evaluate the fertility and pregnancy outcomes following fresh versus frozen-thawed embryo transfer. Materials and methods: The thesis includes four studies using population-based data extracted from Australian and New Zealand Assisted Reproduction Database and Victorian Assisted Reproductive Treatment Authority. The risks of ectopic pregnancy, small/large for gestational age birth, and cycle-based live birth following frozen-thawed embryo transfer were compared with those of fresh embryo transfer. This thesis also investigated the cumulative live birth rate from one oocyte retrieval following a ‘fresh transfer’ strategy versus a ‘freeze-all’ strategy. Results: Compared with fresh embryo transfer, frozen-thawed embryo transfer was associated with a decreased risk of ectopic pregnancy and small for gestational age birth, but an increased risk of large for gestational age birth. The ‘freeze-all’ strategy resulted in a similar cumulative live birth rate as the ‘fresh transfer’ strategy among high responders (>15 oocytes), but did not benefit normal (10–15 oocytes) and suboptimal responders (<10 oocytes). Vitrification was the preferred cryopreservation method for blastocysts. Conclusion: This thesis provides population-based evidence of fertility and pregnancy outcomes following fresh versus frozen-thawed embryo transfer. This thesis suggests that, from a population perspective, the ‘freeze-all’ strategy may benefit some subgroups of patients, but should not be offered universally.

La végétalisation d'espaces en zone urbaine nécessite l'utilisation de grandes quantités de ressource naturelle terreuse. Pour préserver cette ressource non renouvelable, le génie pédologique propose une stratégie de construction de Technosols fertiles à partir du recyclage de déchets et sous-produits. Les propriétés des Technosols sont alors fortement influencées par les matériaux technogéniques qui les constituent. La formulation de mélanges performants pour la croissance des végétaux urbains passe par une analyse scientifique préalable. La fertilité des mélanges et leur évolution au cours du temps peuvent être appréciées par l'étude du processus d'agrégation et du transfert d'éléments nutritifs lors des stades précoces de la pédogenèse. Le modèle expérimental de Technosol construit proposé dans la Thèse développe une méthodologie aboutissant à la sélection de 11 matériaux (ballasts, béton, boues de station d'épuration urbaine, briques, compost de boues et de déchets verts, déchets de balayage de rue, déchets de démolition, déchets verts, terres excavées de profondeur, sous produits papetiers) représentatifs des gisements de déchets recensés au niveau européen et compatibles avec la construction de sol fertile. Le potentiel fertile initial de chaque matériau pur et de certaines combinaisons de mélanges a été mesuré. Puis des expériences menées en conditions contrôlées ont permis d'évaluer l'effet de différents facteurs pédogénétiques (e.g. anthropique, climatique et biologique) sur les processus déterminant de la fertilité des Technosols construits. Les résultats indiquent (i) qu'il est possible de construire un Technosol fertile exclusivement à partir de deux ou trois déchets aux propriétés physico-chimiques complémentaires; (ii) que les propriétés des mélanges sélectionnés peuvent être modélisées à partir des propriétés initiales de leurs matériaux parents.(iii) que lors des premiers stades d'évolution pédogénétique des mélanges, des agrégats stables se forment en fonction de la nature et des propriétés des matériaux parents, (iv) que les transferts d'éléments nutritifs sont fortement dépendants de la nature des matières organiques et du procédé de mélange des particules entre elles. La libération d'éléments nutritifs (e.g. phosphore) serait liée à la taille et la quantité des agrégats formés et en corollaire à la mise en place d'une organisation porale. Les connaissances acquises sur le fonctionnement et l'évolution des Technosols construits à partir de déchets apportent des connaissances nouvelles pour le génie pédologique. La méthode de choix de déchets ainsi que le procédé de formulation de mélanges développés dans ces travaux permettent d'obtenir des mélanges voire des sols construits performants par rapport à des usages attendus. Les modèles d'évolution des mélanges permettent de prédire au cours du temps la fertilité physico-chimique des Technosols construits. Dans le cadre du programme SITERRE-ADEME (2010-2015), les résultats acquis constituent des bases incontournables dans le développement d'un outil d'aide à la décision pour les gestionnaires (e.g. collectivités, bureaux d'étude, entreprises) auquel doit être associée une expertise sur la construction de sol pour la production de biomasse végétale
Greening of urban spaces requires large amounts of arable soil which is a non-renewable resource. To preserve this resource, a strategy is proposed to build fertile Technosols from wastes and by-products by pedological engineering. The properties of Technosols are highly influenced by their constitutive technogenic materials. In order To create favourable mixtures of materials for urban plant growth a preliminary scientific analysis is required. The fertility of the mixtures and their evolution can be assessed by the study of the aggregation process and nutrients transfer during the first stage of pedogenesis. An experimental model of constructed Technosol is proposed in this work. From this model a methodology is developed for the selection of eleven constitutive materials (e.g. bricks, compost made of sludge and green waste, concrete, demolition rubble, excavated earth materials, green wastes, paper mill sludge, sewage sludge, street sweeping wastes, track ballast). Each of these materials is representative of wastes deposits listed European wide and they are suitable candidates for the construction of fertile soils. The fertility of each pure material and of selected mixtures has been determined. Thereafter, experiments under controlled conditions enabled to assess the impact of different pedogenesis factors (e.g. anthropogenic, climatic and biological) involved in the definition of the fertility of constructed Technosols. The results demonstrate (i) the feasibility of the formulation of fertile constructed Technosols exclusively with two or three wastes presenting contrasted physico-chemical properties; and (ii) that the properties of selected mixtures can be modelled using the initial properties of their constitutive parent materials ; (iii) that during the first stage of pedogenesis of the mixtures, depending on parent materials nature and properties, stable aggregates can be formed, (iv) that nutrients transfer are highly dependent on organic matter nature and the process of particles mixing. The delivery of nutrients (e.g. phosphorus) seems to be related to the amounts and size of the formed aggregates and, consequently, to the established porosity. The understanding of the functioning and evolution of Technosols constructed with waste materials provides new knowledge for the development of pedological engineering. The methodology of wastes selection and the mixing process developed in this work enables us to propose mixtures and constructed soils favourable to various uses. The evolution models of the mixtures developed in this work allow the prediction of the physico-chemical fertility of constructed Technosols. The results acquired during this thesis are the main basis of a decision support tool for green spaces operators developed in the framework of the research program SITERRE-ADEME (2010-2015). The use of this decision support tool for plant biomass production, has to be associated with an expertise in soil construction

Face aux crises environnementales et climatiques actuelles, les systèmes de production alimentaire doivent être transformés de toute urgence. Parmi les alternatives possibles, l'agriculture biologique est souvent mise en avant. Cependant, la question de savoir si l'expansion à grande échelle de l'agriculture biologique serait limitée par la disponibilité en nutriments des sols reste encore largement débattue. Jusqu'à présent, des études ont montré qu'à condition de réorganiser en profondeur les systèmes alimentaires, la conversion de 60 % des terres arables à l'agriculture biologique pourrait répondre à la demande alimentaire mondiale. Ces réorganisations incluent une réduction des densités d’animaux et du gaspillage alimentaire, la modification des régimes alimentaires et la relocalisation des élevages et des cultures sur les territoires. Au-delà de ce seuil de 60%, l'azote (N) entrainerait une limitation trop important de la production alimentaire mondiale. Toutefois, ces études n'ont pas examiné si la disponibilité en phosphore (P) des sols pourrait limiter la production de l’agriculture biologique à long terme. Cette question se pose dans la mesure où les engrais minéraux phosphatés, qui contribuent actuellement à plus de la moitié des apports mondiaux de P sur les sols agricoles, sont interdits dans le cadre de l'agriculture biologique. Répondre au manque de connaissances sur ce sujet est primordial, non seulement pour évaluer la capacité de l’agriculture biologique à se développer globalement, mais aussi dans le contexte de l'inévitable épuisement des réserves de roches phosphatées. Dans cette thèse, nous avons tout d'abord quantifié la dépendance de la fertilité actuelle en P des sols agricoles vis-à-vis de l'utilisation passée et présente d'engrais minéraux phosphatés. Nous avons ensuite analysé dans quelle mesure la production de l’agriculture biologique pourrait être affectée par un déficit en P des sols dans un monde 100% biologique. Dans l'ensemble, nous montrons que la fertilité actuelle en P des sols agricoles dépend fortement de l'utilisation cumulée d'engrais minéraux phosphatés sur la période 1950-2017, la moitié du P disponible des sols agricoles mondiaux étant d'origine anthropique. Cette tendance globale cache de fortes disparités entre les pays, reflétant des historiques d’utilisation d'engrais minéraux phosphatés contrastés. La forte dépendance à l'égard des engrais minéraux phosphatés est à la fois une opportunité et un obstacle au développement de l'agriculture biologique. D'une part, elle se traduit souvent par d'importants stocks de P hérités dans les sols, ce qui facilite la transition vers l'agriculture biologique. Cependant, cette dépendance remet en question la durabilité à long terme des systèmes agricoles sans aucun apport de P minéral. Nos simulations d'un monde 100% biologique ont révélé que, si la production agricole serait fortement limitée par l'azote à court terme, un déficit en P des sols agricoles sur le long terme affecterait aussi grandement la production alimentaire, en particulier dans les régions où le niveau actuel de fertilité en P des sols est faible, où les niveaux de production sont élevés et où la part de légumineuses dans les rotations est importante. Après 100 ans de production en agriculture biologique, la production alimentaire mondiale serait réduite de 41 %, les déficits en P des sols des terres arables et des prairies permanentes contribuant respectivement à 39 % et 18 % de cette perte. Dans l'ensemble, notre travail apporte de nouvelles connaissances sur les limitations potentielles de la production de l’agriculture biologique par la disponibilité en P des sols agricoles, soulignant les risques à long terme pour la sécurité alimentaire dans un monde 100 % biologique. Enfin, nous discutons des leviers potentiels qui permettraient de limiter la perte de P des sols agricoles, dont notamment le bouclage du cycle du P
Faced with the current environmental and climate crises, food production systems urgently need to transform. Among possible alternatives, organic agriculture is often put forward. Yet, it is still under debate whether large scale expansion of organic farming would be limited by nutrient availability. So far, studies have shown that provided a strong redesign of food systems including a reduction in livestock densities and food waste, changes in diets and re-location of crops and livestock, the global food demand could be met by converting up to 60% of cropland areas to organic agriculture. Above this threshold, nitrogen (N) limitations would lead to an unsatisfied demand. However, these studies have not considered whether soil available phosphorus (P) could limit organic food production in the long run. This question arises because mineral P fertilizers, which currently contribute to more than half of global soil P inputs to cropland soils, are banned under organic farming. Filling this knowledge gap is of utmost importance not only to assess the ability of organic farming to expand globally but also in the context of the slow and inevitable depletion of phosphate rock reserves. In this thesis, we first quantified the reliance of current agricultural soil P fertility on past and current use of mineral P fertilisers. We then analysed the extent to which organic food production would be affected by the potential soil P deficits in a hypothetical 100% organic world. Finally, we quantified the N and P fertility transfers between grassland and cropland soils in order to assess their contribution to the total nutrient inputs to cropland soils. To simulate a 100% organic world, we coupled two already published models: the GOANIM model and the GPASOIL model and ran them for 100 years at a spatially explicit resolution. Overall, we show that the current P fertility of agricultural soils is highly reliant on the cumulated use of mineral P fertilizers over the 1950-2017 period, half of the global soil agricultural available P being of anthropic origin. This global pattern hides great discrepancies between countries, reflecting contrasting historical uses of mineral P fertilizers and contrasting soil biogeochemical backgrounds. The strong reliance on mineral P inputs is both an opportunity and an obstacle to the development of organic farming. On the one hand, heavy dependence on mineral P fertilizers often results in large inherited soil P stocks, making it easier to switch to organic farming. However, this reliance questions the long-term sustainability of farming systems without any mineral P inputs. Our simulations of a 100% organic world revealed that while crop production would be strongly limited by N in the short term, long term P limitations would also strongly affect food production, especially in places with initial low level of P fertility, high levels of production and a high share of N-fixing crop in rotations. After 100 years of farming the world organically, global food production would be reduced by 41%, with global cropland and grassland soil P deficit contributing to 39% and 18% of that loss respectively. We also show that under organic farming, fertility transfers from grassland to cropland soils contribute to 13% and 37% of total N and P inputs to cropland soils respectively, making cropland production levels reliant on the fertility of grassland systems. Overall, our work provides novel knowledge on the potential limitations of organic production by agricultural soil available P, highlighting long term risks for food security in a 100% organic world. Finally, we discuss various options for limiting this global soil P deficit, which include better connected livestock and crop production systems to enhance fertility transfers, closing the P cycle by limiting soil erosion and by better recycling of household organic waste and human excreta back to agricultural soils

The papers put forward by the candidate represent a significant contribution to three main areas within the body of knowledge of equine reproduction. Namely, i) epidemiological surveys of the efficiency of Thoroughbred racing and breeding, ii) the morphology and functions of the equine placenta and, iii) embryo transfer in the horse. Two extensive surveys on reproductive efficiency of Thoroughbred mares and stallions at stud and factors associated with the failure of Thoroughbred horses to train and race demonstrated that increasing mare age is the greatest limiting factor to an otherwise high rate of fertility in English Thoroughbreds although a high incidence of early embryonic death remains a significant loss to the breeding industry. The racing wastage survey showed little change over the past 20 years in the percentage of 2- and 3-year-old horses that fail to run, the percentage that are never placed in a race and the number that suffer significant injury or illness during their racing careers. Radical and innovative changes to training methods are needed to overcome these problems. The morphology of the equine placenta was examined using gross measurements, stereological-techniques, vascular casting and immunohistochemistry and the findings related to fetal development and postnatal growth. Stereological measurements applied to term placentae established reference parameters such as surface area per unit volume of placental microcotyledons, the total microscopic area of contact between mother and fetus at the placental interface, and placental VI efficiency. Maternal age, parity, size, genotype and nutrition were all shown to alter placental morphology and, hence, pre- and postnatal fetal development. A novel pair of cervical forceps were designed and marketed to provide a simple and practical method for undertaking transcervical embryo transfer in the horse which enables inexperienced operators to transfer horse embryos successfully. These Wilsher Equine Embryo Transfer Forceps have won widespread acclaim and commercial application in the equine veterinary and scientific communities. A pharmacological method to extend donor-recipient synchrony was developed with both commercial and scientific application. Further work also showed the unique ability of the equine embryo to tolerate a very wide window of donor-recipient asynchrony and it provided a valuable research tool with which to study the relevant roles of the conceptus and uterine environment in regulating embryonic differentiation and fetal growth in the mare.

Common to other practice settings, standard in vitro fertilisation (IVF) in California strongly skews the multiple gestation/preterm birth rate upward to approximately 50% of all deliveries, while unassisted conceptions yield this outcome in only 3% of births. Preterm/multiple gestation babies from IVF are “super-utilisers” and consume a disproportionate share of healthcare resources, particularly during the first year of life. However, early experience with molecular cytogenetic techniques has shown that single embryo transfer (SET) with IVF can now lift pregnancy rates to an acceptable level while not altering the normal multiple gestation rate. This approach would effectively solve the preterm and multiple gestation problem historically associated with IVF. Building on the author’s previous research in medically assisted reproduction, the current proposal describes a new public health policy to incentivise SET by modifying the California Insurance Code (benchmark health plan), when it may next be revised in 2015. The proposal would partially cover IVF costs for qualified California residents with the proviso that only one embryo is transferred per procedure after comprehensive chromosomal screening of embryos with array comparative genomic hybridisation (aCGH). This investigation considers the interconnected problems of preterm birth and multiple gestation in a demographic context, showing that although the contribution made by conventional IVF to these adverse outcomes in California is numerically minor, substantial costs can still be recovered by redirecting expenditures away from high-risk IVF deliveries when the increased multiple gestation/preterm birth rate from standard IVF is corrected. This analysis is the first to examine costs calculated for all delivery types in California as a function of antecedent IVF treatment vs. unassisted conception, based on 2009 birth records, and apply this to a new model of comprehensive embryo testing and mandatory SET. These data reveal that even if partially subsidised IVF with aCGH and SET were provided for every California IVF cycle initiated in 2009 (n=18,405), the state would still realise a net surplus of at least $20M per year by stabilising the IVF multiple birth rate at ~3.2%. Thus, California can avoid up to 4,810 iatrogenic preterm/multiple gestation births by shifting the prevailing approach to IVF away from multiple embryo transfers. The proposal is net revenue positive for California because although IVF with aCGH and SET is expensive, the price to obtain this technology is always lower than the cost for one high-risk preterm/multiple birth. While a compelling primary interest exists to lower the multiple birth rate with IVF, this proposal also yields a socially valuable secondary public health benefit by improving general access to this advanced reproductive treatment for all Californians.

My doctoral thesis examines the broad question of whether appropriately designed institutions and policies can address the short- and long-term consequences of determinants of human capital which are "immutable'' by nature or are perceived as such. I consider three different types of immutable determinants of human capital: male versus female biology; colonization; and traditional norms of gender roles. In Chapter 1, I examine whether, and how, change in political regime type affects excess male infant mortality. Analyzing data on more than 3 million live births from sub-Saharan African countries, I exploit within-mother variation in political regime type to find that excess male infant mortality significantly decreases following a transition to democracy. I identify competitiveness of executive recruitment, constraints on the chief executive, and political participation as the features of democracy that matter most. Examining causal mechanisms, I find that democracy fosters the provision of health inputs, including maternal education, tetanus immunization, breastfeeding, and normal birth weight, all of which have stronger health benefits for boys than for girls, despite being found to be ex-ante "gender-neutral'' in my setting. In Chapter 2, I examine how colonial reproductive laws interact with market incentives to shape long-term fertility behavior in Africa. Exploiting the arbitrary division of ancestral ethnic homelands and the resulting discontinuity in institutions across the British-French colonial borders, I find that women in former British areas are more likely to delay sexual debut and marriage, and have fewer children. However, these effects disappear in areas close to sea, where market access and the opportunity cost of childbearing appear to be high irrespective of the colonizer identity. This heterogeneous impact of colonial origins extends to measures of local economic development and household welfare. Examining causal mechanisms, I argue that the fertility effect of colonial origins is directly linked to colonial population policies and reproductive laws and their impact on the use of modern methods of birth control. I find little evidence that the fertility effect of British colonization operates through education or income. While British colonization is linked to higher female education levels, this occurs mainly close to the sea while the fertility effects do not. Again, while income levels differ, the fertility gap between British and French colonies opened prior to 1980, while the income gap opened-up after 1990. This chapter highlights the heterogeneous nature of the colonial origins of comparative fertility behavior and economic development, and implies that economic incentives may overcome historical determinism. In Chapter 3, I examine the interplay between legal origins and pre-colonial cultural norms of gender roles in determining female economic empowerment in sub-Saharan Africa. Taking advantage of the arbitrary division of ancestral ethnic homelands across countries with different legal origins, I directly compare women among the same ethnic group living in civil law countries and common law countries. I find that women in common law countries are significantly more educated, are more likely to work in the professional sector, and are less likely to marry at young age. However, these effects are either absent or significantly lower in settings where ancestral cultural norms do not promote women's rights and empowerment. In particular, I find little effect in bride price societies, patrilocal societies, and societies where women were not involved in agriculture in the past.

La durabilité du fonctionnement des agro-écosystèmes et la gestion des services écosystémiques associés représente un des enjeux majeurs des sciences agronomiques et environnementales.Les systèmes agro-sylvo-pastoraux d'Afrique de l'Ouest (SASP-AO), étudiés depuis longtemps par la communauté scientifique, offrent un cas d’étude pertinent. La fertilité de ces agro-écosystèmes repose traditionnellement sur un taux de recyclage des nutriments très élevé au sein de l'agro-écosystème via la pratique de la jachère et des transferts de nutriments par les mouvements du bétail.Les SASP-AO sont soumis à des pressions socioéconomiques et démographiques fortes qui entrainent des modifications de leur organisation spatiotemporelle et des pratiques agricoles, notamment celles relatives à l'élevage.Dans cette thèse, nous nous sommes intéressés à l'impact de ces modifications sur la production végétale et animale à l'échelle de l'agro-écosystème.Nous avons choisi d’étudier les SASP en développant et analysant des modèles mathématiques de type méta-écosystème. Dans chacun des trois modèles proposés, nous avons cherché à représenter un SASP le plus simplement possible, en incluant les mécanismes biogéochimiques les plus importants (croissance des plantes, minéralisation, lessivage, dépositions…) et les pratiques agricoles d’intérêt. L’objectif était à la fois de comprendre comment ces mécanismes interagissent en fonction des pratiques et d’identifier des propriétés émergentes à l'échelle de l'agro-écosystème.Chacun des modèles a été développé pour étudier l'effet d'un nombre limité de pratiques agricoles portant sur l'organisation des composantes spatiales ou sur la connectivité entre les composantes spatiales.Dans la première partie de cette thèse, nous avons étudié l'influence de la structure des SASP-AO sur la production agricole de ces systèmes. Dans le modèle, quatre sous-systèmes interconnectés sont représentés : l’auréole de case, l’auréole de brousse, la savane et le village. Le modèle est de plus saisonnalisé, la dynamique de la saison sèche étant différente de celle de la saison humide. Avec ce modèle, nous avons étudié l’influence de trois leviers : (1) la durée de rotation et la durée des jachères dans les rotations, (2) la proportion de surface allouée aux différentes zones cultivées (case/brousse) de l'agro-écosystème et (3) la présence/absence du bétail dans l'agro-écosystème. Les résultats issus de ces travaux ont mis en évidence les services écosystémiques fournis par la savane, le rôle de du bétail comme « pompe à nutriments » des zones de pâturage vers les zones cultivées et les interactions entre les effets du bétail et les effets de la jachère sur les flux de nutriments. Dans la seconde partie, nous avons utilisé des outils issus de la théorie du contrôle afin de tenir compte de la variabilité dans le temps des pratiques agricoles. Nous avons ainsi montré qu'en faisant varier la pression d'herbivorie de manière adéquate, un gain supplémentaire de production est possible par rapport à une pression d'herbivorie constante pour une même quantité de nutriments transférée des pâturages vers les cultures.Dans la dernière partie de ce travail, l’optimisation multicritère du fonctionnement de l’agro-écosystème permet d’aborder la complexité des objectifs des SASP-AO comme système de production et de prendre en compte la gestion des risques dans ces systèmes. Nos résultats mettent en avant que les compromis entre production végétale et animale sont liés au choix des plantes cultivées. Nos résultats montrent également que les sources extérieures de nutriments permettent d’augmenter les productions, mais que leur efficience diminue quand leur quantité augmente.À l’interface entre écologie et agronomie, et grâce à l’utilisation conjointe d'outils issus d'autres disciplines, ces travaux de modélisation offrent de nouvelles perspectives pour l'optimisation de la production végétale et la gestion de la fertilité dans les SASP
The sustainability of agro-ecosystem functioning and the management of the associated ecosystem services is one of the major challenges of agronomic and environmental sciences. West African agro-sylvo-pastoral systems (WA-ASPS), which have been studied by the scientific community for a long time, offer an interesting case study. Traditionally, the fertility of these agro-ecosystems relies on a very high rate of nutrient recycling within the agro-ecosystem maintained by both fallowing and livestock induced nutrient transfers.Socio-economic and demographic pressures lead to major changes in the spatial and temporal organization of WA-ASPS and in the associated agricultural practices, including those related to livestock. In this thesis, we are interested in the impact of these changes on crop and meat production at the scale of the agro-ecosystem.We chose to study ASPS by developing and analyzing mathematical models using the ecological concept of meta-ecosystems. In each of the three models proposed, we tried to represent the ASPS as simply as possible, by including the key biogeochemical mechanisms (plant growth, mineralization, leaching, deposition...) and the agricultural practices of interest. The aim was both to understand how mechanisms interact according to the practices and to identify emerging properties at the scale of the agro-ecosystem.Each model was developed to study the effect of a limited number of agricultural practices on the organization of spatial components or on the connectivity between spatial components.In the first part of this work, we studied the influence of the structure of the WA-ASPS on the agricultural production of these systems. In the model, four interconnected subsystems are represented: the compound ring, the bush ring, the savanna and the dwellings. The year is decomposed in two seasons: the dry and the rainy seasons, the dynamic of the system being different for each season. With this model, we studied the influence of three driving-forces on the crop production: (1) the rotation duration and duration of fallows within rotations, (2) the proportion of the agro-ecosystem surface allocated to the different cropland areas (compound/bush) and (3) the presence/absence of livestock in the agro-ecosystem. The results of this work highlight the ecosystem services provided by the savanna, the role of livestock as a "nutrient pump" from rangeland to cropland and the interactions between livestock effects and fallow effects on nutrient fluxes. In the second part, we used tools provided by control theory to take into account the variability over time of agricultural practices. We showed that by varying the herbivory pressure over time in an appropriate way, an additional gain in production is possible (compared to the one obtained with a constant herbivory pressure) for the same amount of nutrients transferred from rangelands to croplands.In the last part of this work, the multi-criteria optimization of the functioning of the agro-ecosystem makes it possible to address the complexity of the objectives of WA-ASPS as a production system and to take into account risks management in these systems. Our results highlight that trade-offs between crop and animal production may be linked to the choice of crops. Our results also show that external sources of nutrients can lead to an increase in productions, but that their efficiency decreases as their quantity increases. At the interface between ecology and agronomy, and by using tools from other fields, this modeling work offers new perspectives for optimizing crop production and fertility management in ASPS

La PLTP est un facteur plasmatique capable de transférer des phospholipides entre les lipoprotéines, mais peut aussi échanger d’autres composés amphipathiques tels le cholestérol non estérifié ou la vitamine E. La vitamine E, connue pour son rôle anti-oxydant, est par ailleurs un facteur clé de la fertilité masculine. Les objectifs de ce travail ont donc consisté à rechercher la présence de PLTP et d’identifier son rôle dans le système reproductif mâle. Dans un premier temps, nous avons mis en évidence que la PLTP était présente dans le plasma séminal humain et qu’elle était responsable à 80% de l’activité de transfert des phospholipides dans ce fluide. Dans un deuxième temps, nous avons examiné les conséquences d’un déficit en PLTP sur la fertilité en utilisant un modèle murin déficient en PLTP (KO-PLTP). Le déficit en PLTP n’affecte que la fertilité mâle, se traduisant par une diminution de la mobilité spermatique progressive chez les souris mâles PLTP -/-, associée à une diminution du nombre d’embryons obtenus par fécondation in vitro réalisée avec des spermatozoïdes de souris mâles PLTP -/- (- 60%, p<0. 05) et à une diminution de la fertilité in vivo avec diminution du nombre de nouveaux-nés (- 32%, p<0. 03). La PLTP est exprimée fortement dans l’épididyme des souris sauvages alors qu’une diminution significative du taux d’alpha-tocophérol est observée dans la tête et la queue de l’épididyme des souris PLTP -/- associée à une diminution du contenu des spermatozoïdes en alpha-tocophérol. Ces observations montrent que la PLTP constitue un nouveau facteur clé de la fertilité mâle, peut-être par le biais d’un transfert de la vitamine E
Phospholipid transfer protein (PLTP) was first described as a plasma factor that facilitates the exchange of phospholipid species between circulating proteins. In addition, PLTP can bind and transfer several other amphipathic compounds, including unesterified cholesterol, lipopolysaccharides, diacylglycerides and vitamin E. Vitamin E is well-known for its anti-oxidative properties and is a major determinant of male fertility. The aim of the present study was to search for the presence of PLTP and to identify the physiological role of this protein in reproductive biology. First, PLTP was detected in human seminal plasma and accounted for almost 80% of the phospholipid transfer activity present in seminal plasma. Secondly, the effect of PLTP on reproductive biology was investigated through the comparison of wild-type and PLTP-knocked out mice. We show that PLTP deficiency is associated with hypofertility of mouse males but not mouse females. PLTP deficiency tended to reduce sperm motility and accounts for a significant decrease in total number of pups produced over a 2-month breeding period of PLTP knocked out mice (-32%, P<0. 03). In vitroo fertilization rates of wild-type oocytes with spermatozoa from PLTP-deficient males were markedly reduced as compared with those measured with spermatozoa from wild-type males (-60%, P<0. 05). PLTP is highly expressed in epididymis of mouse males, and alpha-tocopherol was significantly less abundant in cauda and caput epididymis of PLTP-deficient mice as compared with wild-type counterparts. These observations suggest that PLTP is a new key factor in male fertility, probably via the transfer of vitamin E

O programa de transferencia de renda Bolsa Familia e um importante pilar da seguri- dade social brasileira, mas ha um senso comum de que as transferencias do programa incentivam casais beneficiarios a terem mais filhos. Utilizando base de dados do governo federal (Cadunico e Caixa) e valendo-se dos criterios de eligibilidade, prop6e-se uma ine- dita analise quase experimental para estudar os efeitos das transferencias nao condicionais (UCT) e das condicionais (CCT) sobre a fecundidade das beneficiarias entre os anos de 2011 a 2015, atraves de uma regressao descontinua fuzzy. Problemas de medida associa- dos a base (e.g.: manipulacao, arredondamento, atrito) sao remediados com a estimacao nao parametrica proposta por Gerard, Rokkanen & Rothe (2016), em que se determina limites superiores e inferiores aos efeitos de tratamento. Por um lado, nao ha evidencia de que o componente CCT afete a fecundidade das beneficiarias, mas por outro, o com- ponente mais flexivel do Bolsa Familia, o UCT, possivelmente reduziu a fecundidade das beneficiarias mais pobres, sobretudo no Nordeste. Tais resultados sao contraintuitivos em relacao a literatura te6rica ate entao, mas em linha com a grande maioria dos resultados encontrados em programas similares da America Latina.
The Brazilian cash transfer program Balsa Familia is a very, if not the most, important pil- lar of Brazil\'s welfare system. However, there is a common sense that the program\'s trans- fers incentive beneficiary couples to have more children. Using federal data (Cadunico and Caixa databases) and the eligibility rules for the program, I propose a quasi-experimental approach to verify both unconditional (UCT) and conditional transfers (CCT) on the beneficiaries\' fertility rates between 2011 and 2015, through a fuzzy regression disconti- nuity approach. Measure problems associated with the data (e.g.: manipulation, heaping, attriton), are solved using a non parametric estimation proposed by Gerard, Rokkanen & Rothe (2016), which determines lower and upper bounds for treatment effects. On one hand, there is no evidence that the CCT component affects the beneficiaries\' fertility rates, but on another, the more flexible component of Bolsa Familia, UCT, possibly reduced the fertility rates for the most poor. Those results are counter intuitive with the theoretical literature so far, but in line with the majority of other studies analyzing similar transfer programs in Latin America.

Cette thèse s’est interrogée principalement sur le lien entre l’entraide familiale et la fécondité en contexte de pauvreté. Elle a donc mis en relief l’impact sur la fécondité des changements des comportements des ménages vis-à-vis de l’entraide familiale. Nous avons tenté d’identifier les facteurs de la baisse de la fécondité observée au Cameroun, et de discuter l’idée selon laquelle un affaiblissement du système de l’entraide familiale serait un déterminant de la fécondité. Entre autres, nous avons cherché aussi à relever les transformations subies par les ménages camerounais (configuration et composition), dues à l’impact de la pauvreté sur leurs organisations. En guise de résultats, outre le début d’un affaiblissement du système d’entraide familiale, d’autres facteurs tels que la baisse de la mortalité infanto-juvénile, etc., expliquent la baisse de la fécondité au Cameroun. Si l’on observe donc une persistance de l’entraide familiale au Cameroun malgré la pauvreté, notons néanmoins une montée en puissance de la nucléarisation de la famille qui se traduit par une préférence d’aider ses proches à distance au travers du soutien financier, au lieu de les avoir près de soi à travers la cohabitation
This thesis wondered mainly about the link between the family mutual aid and the fertility in context of poverty. Thus she accentuated the impact on the fertility of the changes of the behavior of the households towards the family mutual aid. We tried to identify the factors of the reduction in the fertility observed in Cameroon, and tu discuss the idea according to which a weakening of the system of the family mutual aid would be a determiner of fertility. Among others, we also looked to raise the transformations undergone by the Cameroonian households (configuration and composition), due the impact of the poverty on their organizations. By way of results, besides the beginning of a weakening of the system of family mutual aid, other factors such as the reduction in the infanto-young mortality, etc., explain the reduction of the fertylity in Cameroon. If we thus observe an obstinacy of the family mutual aid in Cameroon in spite of the poverty, let us note nevertheless an increase in importance of the nuclearization of family which is translated by a preference to help his remote relations through the financial support, instead of having them near one through the cohabitation

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In this article we show evidences that conditional cash transfer programs (CCTs) can be very effective to enhance changes in people reproductive behavior. Using the event of the launching of Bolsa Familia, we first test the hypothesis that teenage pregnancy would be stimulated by being perceived as a potential facilitator of program participation. Then, we use the heterogeneity in the concession of the benefit to adolescent mothers documented between brazilian states as an exogenous source of variation in the incentives faced by the young women in each place, since pregnancy would be perceived as a factor of non-participation in some places. The results of both estimations demonstrate a high level of response of the poorest people of the population to indirect and financially small incentives. Besides suggesting the alteration of Bolsa Familia participation rules, our analysis confirm the potential of CCT programs to achieve voluntarily fertility reduction and maybe even STD prevention, which are relevant to all regions denoted by poverty.
O primeiro artigo desta tese procura medir o impacto do programa Bolsa Familia sobre a gravidez juvenil, discutindo também a utilização de programas de transferência condicional de renda para a diminuição da fecundidade em áreas de pobreza. O segundo artigo realiza um exercício contrafactual para estimar o impacto de aumentos no investimento em educação sobre o consumo, considerando não só o aumento da produtividade, mas também o impacto da nova educação sobre a fecundidade das pessoas.

This study was performed to test the viability of administering a single 40 mg dose of Folltropin-V® (FSH, Bioniche Animal Health) diluted in SRF (MAP-5 50, Sodium Hyaluronate, Bioniche Animal Health) on day 5 of a recipient synchronization protocol to beef cows to evaluate its effect on recipient fertility. All recipients were administered an estradiol 17beta (2.5 mg, IM) and progesterone (50 mg, IM) combination injection on day 0 and a CIDR® (progesterone 1.34 g, Pfizer Animal Health) was inserted. Lutalyse® (dinoprost tromethamine, Pfizer Animal Health, 25 mg, IM) was administered at the time of CIDR removal on day 7, and estradiol 17beta (1 mg, IM) was administered on day 8. On day 16, the presence of at least one corpus luteum (CL), detected via ultrasound, resulted in the recipient receiving an embryo (both fresh and frozen-thawed embryos were used). Embryos were not transferred into cows that did not show the presence of a CL. Dependent variables for which data were collected included circulating progesterone levels at the time of transfer, number of CLs and CL diameter, circumference, and area; measured in millimeters. The study (n=572) consisted of a treatment group (n=268) and a control group (n=304), and included both Bos indicus (Brahman influenced) crossbred (n=115) and Bos taurus (Angus based) cows (n=457). Pregnancy rates for Treated recipients (40.67%A) and Control recipients (52.96%B) differed (P<.05). There was no difference in the mean number of CLs per recipient for Treated (1.14 +/- .03) and Control (1.10 +/- .02) cows, nor was there a difference in progesterone (P4) at the time of transfer for Treated (3.14 +/- .40 ng/mL) and Control (3.23 +/- .18 ng/mL) recipients. Overall, the inclusion of Folltropin-V® diluted in hyaluronan in a FTET synchronization protocol did not improve the fertility of beef recipients.

In this dissertation, I develop theoretical models and an empirical study of the role of social interactions, the evolution of social norms, and their impact on individual behavior. Although my models are consistent with individual utility maximization, they generally emphasize social factors that channel individual decisions and/or shape individuals' preferences. I apply this approach to three different issues: labor supply, fertility decisions, and intergenerational transfers, generating predictions that are more consistent with observed empirical patterns of behavior than standard neoclassical approaches that assume independent preferences, perfect information, and efficient markets. In the first essay, I explain the long-run evolution of working hours during the 20th century in developed countries: the substantial decline for the first three quarters of the 20th century and the deceleration or even reversal of the fall in working hours in the last quarter. I develop a model of the determination of working hours and how this process is affected by both the conflict between employers and employees and the employees' desire to emulate the consumption standards of the rich reference group. The model also explores the effects of direct and indirect policies to limit hours advocated by political representations of workers such as trade unions or leftist parties. In the second essay, I study the coevolution of gender norms and fertility regimes. Since the 1990s, a new pattern of positive correlation between fertility rates and female labor force participation emerged in developed countries. This recent trend seems inconsistent with conventional economic approaches that explain fertility decline as a result of the increasing opportunity costs of childrearing, predicting a negative correlation between fertility and women's labor force participation. To address this puzzle, I develop a model of the evolution of gender norms and fertility in various economic environments influenced by the level of women's wages. Randomly matched spouses make choices related to fertility—labor supply and the division of household labor—based on their preferences shaped by gender norms. In the model, norm updating is influenced by both within-family payoffs and conformism payoffs from social interactions among the same sex. The model shows how changes in economic environments and the degree of conformism toward norms can alter fertility outcomes. The results suggest that the asymmetric evolution of gender norms between men and women could contribute to very low fertility, explaining the positive correlation between fertility and women's labor force participation. Finally, I estimate the effect of exogenously introduced public pensions for the elderly on the amount of private transfers they receive. There has been a long debate whether public transfers crowd out private transfers. Previous empirical studies on this issue suffer from the endogeneity of income that contaminates estimates. I use an exogenously introduced public transfer, the Basic Old Age Pension in Korea, to test the crowding out hypothesis. A considerable proportion of the elderly population, especially women living without a spouse, do not experience the crowding out effect and moreover, among those who do, the size of the effect is relatively small. The results support the redistribution effect of the Basic Old Age Pension targeting the poor elderly in Korea.

The production of haploid sperm is a precondition for sexual reproduction of males. PRDM9 protein is a histone methyltransferase which localizes sites of meiotic recombination in many mammals. Mouse males of the C57BL/6J (B6) strain deficient for Prdm9 (Prdm9-/- ) are sterile, while Prdm9-/- males of PWD/Ph (PWD) strain have reduced sperm count. The comparison of the distribution of trimethylation of histone 3 on lysine 36 (H3K36me3) in genome of Prdm9-/- males of these two strains will help to determine the role of this epigenetic modification on meiotic recombination and fertility of Prdm9-/- males. The second part of this thesis is focused on transgenic males. Male offspring from the first generation of B6 female and PWD male crosses (B6PF1) have reduced fertility parameters due to incompatibility of Prdm9 alleles. The fertility parameters of B6PF1 hybrids carrying CHORI-34-289M8 or RP24-346I22 transgene are even lower. The candidate gene, which participates in the reduction of fertility of the transgenic B6PF1 hybrids, was determined as the proteasome subunit encoding gene Psmb1, because its relative transcription level best correlates with sperm count. The reason of lowered fertility thus might be a defect in proteasome assembly. The investigation of the fitness of transgenic animals is...