Essays on Childhood Environment and Human Capital Acquisition

Childhood is a key period for the acquisition of human capital, and various characteristics of the environment in which a child grows up affect the development of skills and abilities that will determine her lifetime outcomes, from education earnings to health. The two major components of human capitals are cognition, measured by IQ or standardized tests, and non-cognitive skills, also called socio-emotional skills, which encompasses all abilities that allow an individual to successfully evolve in society: self-control, trust, conscientiousness, curiosity, motivation, grit, etc. Between early childhood and adolescence, both cognition and socio-emotional skills can be influenced by a myriad of factors, from parental education and income to family structure to neighborhood characteristics to nutrition to disease to environmental pollution. In the following essays, I explore a few of these pathways, examine whether they are causal or mere correlations, and discuss mechanisms and policy implications. In the first chapter, I study how neighborhood characteristics influenced American children&rsquo;s cognitive and non-cognitive skills at the turn of the millennium, above and beyond the effects of their own family characteristics. In the second chapter, I assess the competing effects on cognition of (i) access to microbiologically safe well water and (ii) exposure to arsenic contamination through well water during childhood in rural Bangladesh. The study sample is a cohort born in the 1970s and early 1980s, when access to well water was quickly increasing, who was part of a 1996 survey that included cognition measures in 1996. In the third chapter, I examine how parent separation affect the socio-emotional development of American children by comparing students whose biological parents remain together through 5th grade to students who live with both their biological parent in early childhood but experience a family structure change between kindergarten and 5th grade. I use propensity score matching and trimming to ensure that I am comparing children whose parents have similar probabilities of splitting up but who experience different realizations of that probability. In all three contexts, I find statistically significant effects and discuss what policies can be used to minimize the negative consequences on children.</p

Phytoplankton dynamics across the Ordovician-Silurian boundary at low palaeolatitudes (Laurentia - Anticosti Island, Québec, Canada; Baltica - Valga, Estonia) : an additional contribution to data on the high-latitude glacial areas of Gondwana

La fin de l’Ordovicien (Hirnantien) est une période charnière de la vie sur Terre. Un ensemble de bouleversements environnementaux, symbolisés par le développement de grandes calottes polaires au Nord-Gondwana, s’accompagne de la première des 'Cinq Grandes Crises Biologiques' du Phanérozoïque. Une révision de la littérature montre que la corrélation directe des évènements biologiques et climatiques avec la base de l'Hirnantien est le résultat de données approximatives. Les dynamiques du microphytoplancton (acritarches) sont alors étudiées au cours de la transition Ordovicien-Silurien. Les données palynologiques publiées, obtenues par analyses de localités de hautes latitudes (Gondwana), sont complétées par l'analyse taxinomique détaillée de 136 échantillons de plateformes carbonatées de faibles latitudes de Laurentia (Île d’Anticosti, Québec) et Baltica (Valga, Estonie). 82 espèces d'acritarches identifiées dans les sections d’Anticosti (52 à Valga) permettent d'établir une nouvelle charte de corrélations biostratigraphiques au sein du bassin d’Anticosti. D'autre part, la répartition paléogéographique du phytoplancton démontre l’existence de deux provinces latitudinales hirnantiennes distinctes (laurentienne/baltique et gondwanienne), expliquant ainsi les difficultés à établir un scénario précis de la crise. Enfin, une dynamique du phytoplancton au sein de ces deux provinces est décrite lors de deux phases glaciaires. La première phase enregistre un « turn-over » des populations concomitant d'une excursion positive des isotopes du carbone. La seconde, plus forte, accompagnée d'une seconde excursion plus marquée, se caractérise par une dynamique de crise avec disparition de nombreux taxa.The Late Ordovician (Hirnantian) is a transition period in the history of life. Deep environmental perturbations, including the development of a large icecap on North-Gondwana, are marked by the first of the “Big Five Extinctions” of the Phanerozoic. A detailed review of literature data shows that direct correlations between biological and climatic events and the base of the Hirnantian Stage are based on many approximations. Microphytoplankton (acritarchs) biostratigraphy and dynamics across the Ordovician-Silurian boundary are thereafter studied. Published palynological data resulting from the study of high latitudes (Gondwana) localities are completed by a detailed taxonomical analysis of 136 rock samples of low latitude carbonate platforms from Laurentia (Anticosti Island, Québec) and Baltica (Valga, Estonia). Eighty-two acritarch species identified in the Anticosti sections, and 52 from the Valga borehole permit to establish a new biostratigraphic correlative chart in the Anticosti Basin. Moreover, the phytoplankton palaeogeographical distribution shows the existence of two distinct Hirnantian latitudinal phytoplanctonic provinces (Laurentian/Baltic and Gondwanan), accounting for the difficulties to establish a precise scenario of the crisis at a global scale. Finally, phytoplankton dynamics are described in the two regions during two glacial phases. The first one records a turn-over in populations concomitantly to a positive carbon isotope excursion. The second one, larger and paired with a second stronger excursion, is characterized by a crisis marked by the disappearances of numerous taxa

Ontogeny of an ordovician trinucleid (Trilobita) from Armorica, France: a morphometric approach

8 fig., 2 tabl.A large number of well-preserved immature exoskeletons enable the first detailed quantitative description of the ontogeny of the trinucleid Marrolithus bureaui (Oehlert, 1895) from the Lower Caradoc of the Armorican Massif (Armorica, northwest France). For the accurate description of cephalic features, a landmark-based approach was adopted in order to recognize ontogenetic instars and to establish the patterns of size increase and shape change during ontogenetic development. The quantitative analysis permitted the demonstration of a progressive shape change in agreement with ontogenetic ordination and a comparison of the timing of size and shape changes. Changes that took place during the meraspid period included, in particular, the development of a more pronounced sub-quadrangular cephalic outline, a compression (sag.) of the glabella and a size decrease until disappearance of the alae in late stages. This quantitative ontogenetic reconstitution of Marrolithus bureaui might be considered as a reference for the better understanding of phylogenetic affinities between other trinucleid species

The end-Ordovician glaciation and the Hirnantian Stage: A global review and questions about Late Ordovician event stratigraphy

This paper proposes a global review of Hirnantian event stratigraphy. The Hirnantian GSSP in south China is tentatively correlated with latest Ordovician strata from the peri-Gondwanan "glacial" regions. Problems of biostratigraphical correlation are highlighted. At a worldwide scale, the major biostratigraphically useful fossil groups (graptolites, chitinozoans, brachiopods, conodonts, acritarchs) are analysed and their limits for global correlation of the uppermost Ordovician are discussed. Palaeobiogeographical disparities are invoked as the primary cause of the difficulty in establishing an effective Late Ordovician global biostratigraphical scheme. As an alternative correlative tool, the HICE (Hirnantian Isotopic Curve Excursion) event is often put forward in the literature. However, carbon isotope chemostratigraphy shows, like biostratigraphy, some limits to the present state of knowledge. No good independent biostratigraphical control of the HICE exists in both shallow carbonate deposits and deeper shaly ones. Recent studies have also demonstrated inconsistencies between carbon isotopic signals obtained from organic (delta(13)C(org)) and inorganic (delta(13)C(carb)) carbon species, further complicating the use of the HICE as an isochronous benchmark. All of these difficulties for Hirnantian event stratigraphy are discussed in detail in order to enable them to be overcome in the future. Precise Late Ordovician and early Silurian event stratigraphies are essential for the understanding of the mechanisms linked to the first of the "Big Five" extinctions. (C) 2009 Elsevier B.V. All rights reserved

Acritarchs from the Ordovician-Silurian boundary beds of the Valga-10 drill core, southern Estonia (Baltica) and their stratigraphical and palaeobiogeographical implications

Fourteen samples of the Valga-10 drill core, south Estonia, from the lower Jelgava Formation (middle Pirgu Regional Stage, Upper Katian) to the lowermost Ohne Formation (lowermost Juuru Regional Stage, Lower Rhuddanian) were investigated for acritarchs. The section is biostratigraphically and chemostratigraphically well constrained; it comprises the rugata, taugourdeaui and scabra chitinozoan zones, the ordovicicus and giradeauensis conodont zones and the Hirnantian Isotopic Carbon Excursion (HICE). The good preservation allowed the identification of three prasinophyte phycomata and 52 acritarch species including the four new species Evittia porkuniensis, Helosphaeridium tongiorgii, Nexosarium leherissei and ?Veryhachium bulliferum. One new combination is proposed: Poikilofusa obliquipunctata (Uutela & Tynni 1991) comb. nov. Comparison with contemporaneaous palynofloras shows that eastern Laurentia and Baltica share a high number of species during the latest Katian-Hirnantian. Some of these species show a potential for future improvement of biostratigraphical correlation between the uppermost Katian-Hirnantian strata of low to mid-latitude carbonate platforms in eastern Laurentia and Baltica. Conversely, significant taxonomic differences exist between the assemblage studied and typical Gondwanan palynofloras. These results suggest that the Laurentian/Baltic and Gonwanan phytoplanktonic palaeoprovinces existed during latest Ordovician times. Published data reveal similar distribution pattern for chitinozoans and graptolites during the Hirnantian. A bathymetric ridge rise associated with the opening of the Rheic Ocean, coupled with the Hirnantian glacially-driven sea-level fall might have prevented water mass exchange and mixing/migration of phytoplankton between Gondwana and Laurentia/Baltica, thus being at the origin of the observed acritarch bioprovincialism. Additionally, distribution and diversity patterns of acritarchs are compared to those of other microfossils in the Valga-10 section. Near the base of the Hirnantian (Porkuni Regional Stage), benthic organisms (ostracods and scolecodonts) and phytoplankton (acritarchs) show increasing diversity with appearances of new taxa and new morphologies. Planktonic (chitinozoans) and nektonic (conodonts) organisms show a different pattern, with a decline in diversity during the earliest Hirnantian and a marked increase in the later part of the stage. Two alternative hyptotheses are proposed to explain these differences in diversification patterns: (1) the development of a shallower, proximal environment in the locality studied during the Hirnantian glaciation may have been more favourable to the diversification of benthonic organisms; (2) the planktonic and nektonic organisms suffered the effects of glaciation more than benthonic ones

Remplacer un routeur par un serveur Linux : retour d'expérience des passerelles d'accès à Grid'5000

National audienceGrid'5000 est une infrastructure pour la recherche en informatique distribuée (Clouds, réseau, HPC…). La plateforme est composée d'environ 700 noeuds, mis à disposition des chercheurs, répartis sur 8 sites reliés entre eux par un réseau 10Gbits/s fourni par Renater. L'interconnexion de Grid'5000 avec Internet est réalisée par 2 routeurs.Jusqu'en 2018, des équipements réseaux traditionnels étaient utilisés mais les performances de ces routeurs n'étaient pas suffisantes pour répondre aux besoins des chercheurs, qui téléchargent des données de plus en plus volumineuses depuis Internet (images Docker, grands jeux de données, ...)Les débits plafonnaient en effet à 150Mbits/s bien loin du Gigabit/s qu'ils sont supposés atteindre. Les devis réalisés pour les remplacer par des équipements plus performant ayant un coût trop élevé (entre 29k€ et 38k€), nous avons fait le pari de changer à moindre coûts les équipements actuels pour des serveurs Linux classiques, fonctionnant sous Debian.Pari réussi : les performances sont convaincantes, nous saturons sans problème le lien 1G et depuis, avons même basculé notre accès internet à 10Gbit/s avec succès.De plus, l'utilisation d'un système Linux simplifie la configuration de l'équipement : gestion via Puppet, mise en place d'un proxy cache, développement de nouveaux services réseaux pour les chercheurs, ...Nous vous proposons donc un retour d'expérience sur cette migration vers des serveurs Linux. Nous présenterons la configuration matérielle et logicielle utilisée, comment sont effectuées les fonctions de routage et de filtrage, les services mis en place qui n'auraient pas pu l'être sur des équipements traditionnels, ainsi que les performances obtenues

Cryptospore assemblages from Upper Ordovician (Katian-Hirnantian) strata of Anticosti Island, Quebec, Canada, and Estonia: Palaeophytogeographic and palaeoclimatic implications

Rich palynological assemblages have been recovered from deposits of Hirnantian age in Anticosti Island (Quebec, Canada), and in borehole Valga-10 in southern Estonia. The assemblages are well preserved, and include acritarchs, chitinozoans. and cryptospores. The age of the deposits is well constrained by means of palynomorphs (acritarchs and chitinozoans) as well as sequence stratigraphic and chemostratigraphic correlations. Cryptospore assemblages from the two localities are similar and are also broadly comparable to the few known coeval assemblages described elsewhere. They include 11 genera and 20 species, and testify to the presence of an extended and diverse flora during Hirnantian times in Laurentia and, for the first time, also in Baltica. The present findings contribute to an improved knowledge of origin and early development of vegetative cover. The recovery of diverse and abundant cryptospores in Himantian deposits may be related to increased input of land-derived sediment during the global sea-level fall linked to the Late Ordovician glaciation, but it also demonstrates that the early land plants may have tolerated a wide range of climatic conditions. (C) 2011 Elsevier B.V. All rights reserved

Abnormal forms of acritarchs (phytoplankton) in the upper Hirnantian (Upper Ordovician) of Anticosti Island, Canada

A detailed study of Late Ordovician-early Silurian acritarchs (Palaeozoic phytoplankton) from Anticosti Island (Quebec, Canada) revealed an unusually high abundance of abnormal forms from the upper Hirnantian carbonate strata (uppermost Ordovician) of the Ellis Bay Formation in the western part of the island (member 6, Spinachitina taugourdeaui chitinozoan Biozone). The objective of this paper is to describe these abnormal forms in detail. Two species are particularly affected: Disparifusa psakadoria Loeblich and Tappan, 1978 presents abnormally hypertrophied central vesicles, whereas Peteinosphaeridium laframboisepointense nov. sp. has appendices that are fused along their length. The abnormal forms of acritarchs occur in rocks deposited during periods that are near time-equivalents to those of maximum ice-sheet extensions on Gondwana during the Hirnantian glaciation. Although this stratigraphic level corresponds to an interval of strong perturbations of the global carbon cycle, the exact factors causing the observed malformations remain unknown. (C) 2011 Published by Elsevier B.V