Highway subsoils in cold countries are subject to increased thermal conductivity, disruption of natural moisture circulation as well as dynamic loading and application of de-icing chemicals in the winter months. In this work, the moisture mass transfer in a state of vapour flow and the de-icing chemical migration were considered during unidirectional freezing. The moisture mass transfer in a gaseous state was previously widely neglected in the exploration of frost heave. To conduct freeze-thaw cycles with increased lengths of soil samples and a modified slow freezing technique, an environmental chamber of nine samples capacity was designed. Supplying the non-saline samples with either 11 or 22 g/L sodium chloride solution signified chemical mass transport over the sample length and a significant change in temperature-moisture distribution when compared to deionised water supplied test results. The presented conceptual model with vapour mass transfer was based on the thermodynamic equilibrium of vapour density with temperature change and the phase transition to ice during thermal energy withdrawal. Compared to the widely used coupled heat-mass models, the vapour flow based model clearly explained the driving forces and presented a much easier algorithm for calculation. The de-icing chemical displacement was explained as the migration of the dissolved ions together with hygroscopic water transport, which in turn, was driven by cryosuction forces. The reduction of hydraulic conductivity during the secondary salinisation with sodium chloride was caused by chemical osmosis, which tended to equalise the solute concentration in pore water over the sample length. The research outcomes indicate a significant contribution to the future perspectives on frost heave modelling and prognosis. Further research could extend this work by inclusion of the vapour mass transfer in quantitative analysis for soil freezing. The effect of secondary salinisation should be also foreseen in the long term prognosis for highway subsoils exploitation.

[pt] A formação de professores vem assumindo posição de destaque nas discussões relativas às políticas públicas, bem como nas investigações e publicações da área. O estudo da questão da formação continuada de professores envolve um número considerável de autores que aponta a insuficiência da formação inicial para o desenvolvimento profissional do professor e a necessidade de se levar em conta o saber do professor e a escola como lócus de formação docente. Esse consenso põe em destaque a necessidade de se pensar uma formação continuada que valorize tanto a prática realizada pelos docentes no cotidiano escolar quanto o conhecimento que provém das pesquisas realizadas na universidade, de modo a articular teoria e prática na formação e na construção do conhecimento profissional do professor. Tendo essa perspectiva como pano de fundo, procurei, neste trabalho, caracterizar a formação continuada de professores que acontece na escola fundamental pública do município do Rio de Janeiro. A suposição inicial é a de que essa formação acontece em experiências formalizadas de educação continuada, mas também, e, especialmente, no cotidiano do espaço escolar. Nesta perspectiva, o foco da pesquisa esteve dirigido à formação continuada que acontece no interior da escola, nos diferentes momentos e instâncias em que há trocas entre professores e destes com outros profissionais da escola. Para realizar o objetivo de caracterizar a formação continuada de professores, procurei investigar e cotejar a formação continuada de professores em escolas de ensino fundamental organizadas em ciclos, nas dimensões macro e mesossocial de análise. Na dimensão macrossocial, foram utilizados os dados do SAEB 2001 (Sistema Nacional de Avaliação da Escola Básica) para descrever e explorar algumas das características da formação continuada oferecida pelas escolas públicas municipais freqüentadas pelos alunos cariocas. Na dimensão mesossocial, foi feito um estudo de caso da formação continuada oferecida numa escola pública de ensino fundamental do nosso município. / [en] The teachers formation is assuming prominence position in the relative discussions to the public politics, as well as in the investigations and publications of the area. The study of the subject of the teachers continuous formation involves a considerable number of authors that point the inadequacy of the initial formation for the teacher s professional development and the need of considering the teacher s knowledge and the school as lócus of educational formation. That consent puts in prominence the need to think a continuous formation that values the practice developing by the teachers in the daily school as the knowledge that comes from the researches accomplished in the university, in way to join theory and practice in the formation and in the construction of the teacher s professional knowledge. In this perspective as backdrop, I sought, in this work, to characterize the teachers continuous formation that happens at the public fundamental school of the municipal district of Rio de Janeiro. The initial supposition is that formation happens in formalized experiences of continuous education, but also, and, especially, in the daily of the school space. In this perspective, the focus of the research was directed to the continuous formation that happens inside the school, in the different moments and levels in that there are changes among teachers and of these with other professionals of the school. To accomplish the objective of characterizing the teachers continuous formation, I investigate and to compare the teachers continuous formation in schools of fundamental teaching organized in cycles, in the dimensions macro and analysis mesossocial. In the dimension macrossocial, the data of SAEB 2001 were used (National System of Evaluation of the Basic School) to describe and to explore some of the characteristics of the continuous formation offered by the municipal public schools frequented by the students of Rio de Janeiro. In the dimension mesossocial, it was made a study of case of the continuous formation offered at a public school of fundamental teaching of our municipal district.

La Méditerranée est caractérisée par une grande variété de régimes trophiques qui s'explique par les apports fluviaux, les ratios azote/phosphore particulièrement élevés dans le bassin oriental, et par les processus hydrodynamiques en particulier le mélange vertical dans les régions situées au nord. Cette thèse qui s'inscrit dans le cadre du projet MerMEX, composante du chantier MISTRALS, a pour objectif l'étude des cycles biogéochimiques en Méditerranée. Elle s'appuie en particulier sur les observations acquises dans le cadre du projet DeWEx et sur la modélisation couplée physique biogéochimie 3D. À l'échelle du bassin et à l'échelle régionale du sous-bassin occidental. La première étude à l'échelle du bassin sur une période de 10 ans a permis d'effectuer une classification de régimes biogéochimiques, en fonction de leurs caractéristiques physiques et biogéochimiques. Les zones oligotrophes présentes au sud du bassin oriental et occidental sont caractérisées par une faible efflorescence et par de grandes profondeurs de nutriclines. Tandis qu'au nord du bassin, au large de Rhodes, en mer Adriatique et dans le bassin Liguro-provençal, le régime oligotrophe estival est suivi en hiver par une dynamique verticale intense, la convection profonde. Cette dernière est considérée comme le moteur de la circulation thermohaline. Elle entraine un enrichissement des eaux de surface en sels nutritifs qui permet une efflorescence rapide et intense au printemps. L'océan Atlantique représente une source de matière organique pour la Méditerranée. Cette mer représente en revanche une source de sels nutritifs pour l'Atlantique. Ensuite, un modèle à très haute résolution a été imbriqué dans le modèle de bassin pour quantifier les processus physiques et biologiques qui déterminent la variabilité temporelle de la disponibilité et de la stœchiométrie des sels nutritifs en Méditerranée nord-occidentale. La convection profonde hivernale entraîne une homogénéisation des propriétés biogéochimiques sur la colonne d'eau, et une stœchiométrie vers des valeurs estivales. Cette région bascule d'un régime d'eutrophie lors de la convection profonde vers un régime oligotrophe après le bloom de printemps. Lors du premier régime la production primaire est dominée par une production nouvelle en surface, alors que lors du deuxième régime la production phytoplanctonique de subsurface est essentiellement régénérée. Les masses d'eau adjacentes à la zone de convection et celles situées au sud sont caractérisées par une dominance de production régénérée toute l'année. Une partie de la matière organique particulaire est exportée en dessous de la couche épipélagique. Cet export de matière organique est variable et est fortement lié à la dynamique verticale des masses d'eau. / The Mediterranean Sea is characterized by various trophic regimes due to river inputs, as well as heterogeneous nitrogen to phosphorus ratios and hydrodynamic processes, in particular vertical mixing. The objective of this thesis that was performed in the framework of the MISTRALS program is the study of the biogeochemical cycles of these various regimes that composed the Mediterranean. It is mainly based on the in situ observations collected during DeWEx project and on 3D physical/biogeochemical modeling at the scale of the entire basin and at the regional of the western sub-basin. The first study is a ten-year basin scale study which allows an ecological classification, giving bioregions in function of their physical and biogeochemical properties. Southern oligotrophic areas in both eastern and western sub-basins are characterized by low efflorescence and deep nutriclines. While in the north, near Rhodes Island, in the southern Adriatic Sea and in the Liguro-Provencal sub-basin, the summer oligotrophic regime is altered annually by intense vertical dynamics, the deep convection. This process is considered as a driving force of the thermohaline circulation and entrains an enrichment of nutrients in surface layer which allows rapid and intense blooms in spring. The Mediterranean receives organic matter from the Atlantic Ocean, while, it is a source of inorganic matter for the Atlantic. In a second part of this thesis, a high resolution model on the western sub-basin was embedded in the basin model to quantify the physical and biological processes that determine the temporal variability of the nutrient stocks and their stoichiometry. The north-western Mediterranean turns from an eutrophic regime during deep convection to an oligotrophic regime after the spring bloom. During the eutrophic regime new production dominates the primary production at the surface while during the oligotrophic regime primary production is essentially associated to subsurface regenerated one. Adjacent water masses of the convection zone and west-southern regions are characterized by a dominance of regenerated production all over the year.

M-theory, a generalization of string theory, motivates the search for examples of volume minimizing cycles in Riemannian manifolds of G2 holonomy. Methods of calibrated geometry lead to a system of four coupled nonlinear partial differential equations whose solutions correspond to associa- tive submanifolds of R7, which are 3-dimensional and minimize volume in their real homology classes. Several approaches to finding new solutions are investigated, the most interesting of which exploits the quaternionic structure of the PDE system. A number of examples of associative 3-planes are explicitly given; these may possibly be projected to nontrivial volume minimizing cycles in, for example, the G2-manifold R6 × S1.

acase@tulane.edu / Relative Sea-Level (RSL) change influences surface processes and stratigraphic architecture of deltaic systems and has been studied extensively for decades. However, we still lack a quantitative framework to define what constitutes a small vs. large or short vs. long RSL cycle. We explore these questions with a suite of physical experiments that shared identical forcing conditions with the exception of sea-level. We utilize two non-dimensional numbers that characterize the magnitude and period of RSL cycles. Magnitude is defined with respect to the maximum autogenic channel depth, while the periodicity is defined with respect to the time required to deposit one channel depth of sediment, on average, everywhere in the basin. The experiments include: 1) a control experiment lacking RSL cycles, used to define autogenic scales, 2) a low magnitude, long period (LMLP) stage, and 3) a high magnitude, short period (HMSP) stage. We observe clear differences in the response of deltas to the forcing in each experiment. The RSL cycles in the HMSP stage induce allogenic surface processes and stratigraphic products with scales that exceed the stochastic variability found in the control stage. These include the generation of rough shorelines and large temporal gaps in the stratigraphy. In contrast, the imprint of LMLP cycles on surface processes and stratigraphy is found in properties that define the mean state of a system. These include the mean shoreline location and extraction of sediment inbound of the mean shoreline. This work demonstrates the effectiveness of defining RSL cycle magnitude and period through autogenic scales and provides insights for generation of forward stratigraphic models influenced by RSL change. / 1 / Lizhu Yu

No description available.

Le cadre de cette thèse est l'étude de l'anneau des cycles algébriques de la jacobienne d'une courbe lisse, tensorisé par Q. Les cycles sont étudiés sous l'angle de la décomposition de Beauville, c'est-a-dire celle en espaces propres pour les opérateurs k_* et k^* associés aux homothéties k : x -> kx . Plus précisément, on s'intéresse aux cycles tautologiques, ceux dans le plus petit sous-anneau contenant (le plongement de) la courbe, stable par les opérations élémentaires : intersection, produit de Pontryagin, opérateurs k_* et k^*.<br /><br /> L'objectif de cette thèse est de montrer comment calculer de nouvelles relations entre cycles modulo équivalence algébrique en fonction des systèmes linéaires admis par la courbe. <br /><br />Le point de départ de ces calculs est une formule obtenue par Elisabetta Colombo et Bert van Geemen précisant la classe algébrique d'un pinceau (considéré comme sous-variété du produit symétrique de la courbe) dont ils déduisent de premiers résultats d'annulation. On étend cette formule aux systèmes linéaires de dimension supérieure (et à l'anneau de Chow) pour obtenir d'autres résultats d'annulation.

Dans cette thèse, je relie la théorie, plutôt arithmétique, des modules de cycles de M.Rost à la théorie plus géométrique des faisceaux avec transferts invariants par homotopie de V.Voevodsky. Je montre précisément que cette dernière catégorie est une localisation de la catégorie des modules de cycles. De plus, en s'inspirant de la construction des spectres de la topologie algébrique, j'introduit la notion de module homotopique avec transferts à partir des faisceaux invariants par homotopie avec transferts. La catégorie formée par ces modules est équivalente à la catégorie des modules de cycles, prolongeant ainsi l'affirmation concernant les faisceaux homotopiques. Ceci me permet de redémontrer à l'aide des résultats de M.Rost que les faisceaux invariants par homotopie avec transferts ont une cohomologie invariante par homotopie, résultat déjà obtenu par V.Voevodsky. Par ailleurs, j'en déduis que la catégorie des modules de cycles est abélienne de Grothendieck, et munie d'une structure monoïdale telle que la K-théorie de Milnor est l'élément neutre. Par ailleurs, nous montrons comment les techniques employées se prolongent à la catégorie des motifs, obtenant ainsi des formules qui mettent en jeu les triangles de Gysin. On donne ainsi un lemme qui permet d'interpréter géométriquement la ramification au sens des anneaux de valuations discrètes d'égales caractéristiques. Le travail s'achève sur la définition de certains pro-motifs baptisés motifs génériques. Ce sont des pro-objets de la catégorie dérivée des motifs mixtes, associés à des extensions de type fini du corps de base (supposé parfait). On considère aussi que ces motifs peuvent être "twistés" par le motif Z(1)[1] ou une de ses puissances par un entier relatif n quelconque. De manière surprenante, chacune des données des pré-modules de cycles a en fait son analogue en tant que morphisme de motifs génériques. Et par ailleurs, les relations structurales sur les données des pré-modules de cycles sont vraies dans la catégorie des motifs génériques, réalisant ainsi l'incarnation géométrique des axiomes plutôt arithmétiques des pré-modules de cycles.

Since the end of World War Two, the US unemployment rate has remained constant while the EU unemployment rate started to increase at the beginning of the 1970s. This increase in aggregate unemployment hides dramatic differences across skill groups: the increase has remained fairly small for high-skilled workers, while it is usually considerable for the least skilled workers. What caused these developments still remains a debated issue. A possible explanation is the size of the labor market institutions, much more developed on this side of the Atlantic. To study this question, we construct an intertemporal general equilibrium model. We start from the standard Real Business Cycle (RBC) model and we extend it by adding labor market frictions and institutions (minimum wage, employment protection and unemployment benefits). We also further develop the model along the skill dimension, by assuming that the population is composed of low- and high-skilled workers. The main conclusion is that rigid institutions, and especially rigid wages, may well play an important role, direct or indirect through the interactions with exogenous shocks, to explain the relative rise in the European unemployment rate, and especially the low-skilled unemployment rate. We also show that reductions in employer's contributions, targeted at the minimum wage, lead to a fall in the destruction of the less productive jobs and therefore strongly stimulate low-skilled employment, while increasing the welfare of all individuals.

Thesis (D.M.A.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references.