Rozprawy doktorskie na temat „Primitive elements”

The key result linking the additive and multiplicative structure of a finite field is the Primitive Normal Basis Theorem; this was established by Lenstra and Schoof in 1987 in a proof which was heavily computational in nature. In this thesis, a new, theoretical proof of the theorem is given, and new estimates (in some cases, exact values) are given for the number of primitive free elements. A natural extension of the Primitive Normal Basis Theorem is to impose additional conditions on the primitive free elements; in particular, we may wish to specify the norm and trace of a primitive free element. The existence of at least one primitive free element of GF(qn) with specified norm and trace was established for n ³ 5 by Cohen in 2000; in this thesis, the result is proved for the most delicate cases, n = 4 and n = 3, thereby completing the general existence theorem.

Ce travail est fondé sur la théorie des bigèbres bidendriformes, développée par Foissy, qui sont des algèbres de Hopf particulières où le produit et le coproduit peuvent être scindés en deux. Son théorème principal est: Une bigèbre bidendriforme est générée librement par ``l'espace des éléments totalement primitifs'' en tant qu'algèbre dendriforme. Une conséquence est l'auto-dualité des bigèbres bidendriformes.Parmi les nombreuses algèbres de Hopf, Hivert a défini l'algèbre des fonctions quasi-symétriques en mots, notée WQSym. En prouvant que WQSym est une bigèbre bidendriforme, Novelli-Thibon résolvent la conjecture de Duchamp-Hivert-Thibon sur l'auto-dualité de WQSym. Cependant, comme aucune construction générale de l'ensemble des totalement primitifs n'est formulée, nous n'avons pas d'auto-morphisme explicite pour le passage de la primale à la duale.La question centrale de cette thèse est donc de construire un isomorphisme bidendriforme entre WQSym et sa duale. Cette construction passe par la décomposition des mots tassés à l'aide de deux nouvelles opérations que nous avons définies. En outre, pour illustrer ces décompositions, nous avons créé une nouvelle famille d'objets combinatoires: les forêts d'arbres biplans. Certains sous-ensembles de mots tassés ne peuvent être décomposés par ces opérations. Nous avons prouvé que leurs séries génératrices sont égales aux dimensions de l'espace des éléments totalement primitifs. L'intérêt des forêts biplanes est de faire apparaître visuellement les sous-ensembles de mots tassés indécomposables.Ces forêts biplanes sont donc la forme idéale pour indexer des nouvelles bases, que nous avons créées, de l'algèbre WQSym et sa duale. En effet, il est aisé d'en extraire un sous-ensemble qui définit deux bases des espaces totalement primitifs de WQSym et sa duale. Enfin, des arbres biplans bicolores permettent d'obtenir un isomorphisme bidendriforme par un simple échange de couleurs, ce qui répond à notre question initiale et constitue le résultat principal de cette thèse.Après l'obtention de ce résultat, nous nous intéressons aux relations entre les opérations évoquées. Nous remarquons alors fortuitement que ces opérations vérifient des relations semblables à des opérades bien connues (dupliciale déformée, L-algèbre, bigraft) mais qui sont a priori sans lien avec l'opérade dendriforme. Nous prouvons que l'ensemble des mots tassés munis de ces opérations décrit une algèbre sur ces opérades et en donnons des sous-ensembles de générateurs.L'algèbre PQSym, indexée par les fonctions de parking, est très similaire à WQSym, mais aussi plus complexe et serait un premier pas vers la généralisation de notre résultat principal. La question de généraliser ce résultat aux fonctions de parking relève à la fois de la combinatoire et de l'algèbre. Nous présentons ce qui est sans doute le premier ingrédient de cette généralisation. Il s'agit du calcul d'un changement de base où le produit de mélange des valeurs est sans chevauchement.Nous terminons cette thèse par une partie expliquant notre démarche expérimentale de recherche utilisant SageMath. Nous décrivons les tutoriels que nous avons conçus sous la forme de notebooks et mis en ligne à disposition des autres chercheurs. Nous y présentons le code qui permet de vérifier tous nos résultats sur des exemples calculés par des algorithmes
This work is founded on the theory of bidendriform bialgebras, developped by Foissy, which are particular Hopf algebras where the product and the coproduct can be split into two parts. His main theorem is: A bidendriform bialgebra is freely generated by ``the space of totally primitive elements'' as a dendriform algebra. A consequence of this is the self-duality of bidendriform bialgebras.Among the many Hopf algebras, Hivert defined the algebra of word quasi-symmetric functions, denoted WQSym. By proving that WQSym is a bidendriform bialgebra, Novelli-Thibon solved the Duchamp-Hivert-Thibon conjecture on the self-duality of WQSym. However, since no general construction of the set of totally primitive was formulated, we do not have an explicit isomorphism between the primal and the dual.The central question of this thesis is the construction of a bidendriform isomorphism between WQSym and its dual. This construction goes through a decomposition of packed words using two new operations that we havedefined. Furthermore, to illustrate these decompositions, we have created a new family of combinatorial objects: forests of biplane trees. Some subsets of packed words cannot be decomposed by these operations. We proved that their generating series are equal to the dimensions of the space of the totally primitive elements. The interest of biplane forests is to visually reveal the subsets of indecomposable packed words.These biplane forests are therefore the ideal form for indexing the new bases, that we have created, of the algebra WQSym and its dual. In fact, it is easy to extract from them a subset which defines two bases of totally primitives spaces of WQSym and its dual. Finally, bicolored biplane trees allow us to obtain a bidendriform isomorphism by a simple exchange of colors, which answers our initial question and constitutes the main result of this thesis.After obtaining this result, we study the relationships between the aforementioned operations. We then remark fortuitously that these operations verify relations similar to well-known operads (skew-duplicial, L-algebra,bigraft) but which are unrelated to the dendriform operad. We prove that the set of packed words endowed with these operations describes an algebra over these operads and give subsets of generators.The PQSym algebra, indexed by parking functions, is very similar to WQSym, but also more complex and would be a first step towards a generalization of our main result. The question of generalizing this result to parking functions is both combinatorics and algebra. We present what is undoubtedly the first ingredient of this generalization. This is the calculation of a change of bases where the shuffle product on values is not overlapped.We end this thesis with a part explaining our experimental approach of research using SageMath. We describe the tutorials that we have designed in the form of notebooks and made available online for other researchers. We present the code that allows to check all our results on examples calculated by algorithms

Un tema en l'estudi de l'adquisició del llenguatge que ha atret molt l'atenció és la naturalesa dels primers verbs. Als 2 anys, els nens comencen a combinar paraules i a produir els primers verbs. Els elements verbals apareixen més tard que els substantius i es refereixen als conceptes relacionals en el món que estan representats a la sintaxi a través de l'estructura argumental. Aquesta tesi té com a objectiu examinar les característiques de les primeres produccions verbals en italià. L'aparició dels verbs implica el domini d'un procediment d'assignació dels papers semàntics a les posicions sintàctiques. El tema objecte d'estudi té conseqüències no només per a la descripció de l’evolució de l'adquisició del lèxic, sinó també per a la definició d'un model general de la interfície entre la sintaxi i la semàntica lèxica en les primeres etapes. La proposta és que les característiques sintacticosemàntiques estan actives en la gramàtica del nen a l’hora de determinar la derivació oracional. Els verbs impliquen significats estructurals i idiosincràtics: mentre que el significat estructural es deriva dels marcs sintàctics (del nombre i característiques dels arguments) en què un verb pot aparèixer, el significat idiosincràtic es troba en les relacions en el món que cada arrel verbal denota. L'arquitectura de la interfície sintaxi-semàntica dels verbs implica un procediment de projecció des d'uns marcs sintàctics a moltes relacions en el món i viceversa. El significat estructural dels primers verbs s’explora mitjançant una anàlisi de la distribució dels arguments manifestos i dels auxiliars en un corpus de parla espontània de nens i adults. Els resultats mostren que les classes lèxiques dels verbs influeixen en la distribució dels subjectes nuls i en l'elecció de la posició oracional en la qual els subjectes s'expressen. Les classes de verbs són rellevants també per a la selecció i la distribució dels auxiliars: els nens seleccionen correctament els auxiliars en funció de la informació lèxica sintàctica codificada en els SV. Quan apareixen els primers verbs, els nens estan aprenent alhora les derivacions sintàctiques que impliquen el SFlexió i les projeccions del SComplementador. Es troben algunes diferències entre la gramàtica del nen i la dels adults en els dominis sintàctics utilitzats per a la expressió dels subjectes a la interfície sintaxi-fonologia: un spell-out inicial més baix pot dificultar les derivacions sintàctiques que impliquen les projeccions oracionals on es comproven els trets semàntics del discurs com a Tòpic i Focus. S’han dissenyat dues tasques experimentals per tal d’observar els efectes de la presència d'un objecte explícit dins el SV en la determinació de la lectura aspectual. La interacció entre l'aspecte perfectiu codificat en el pretèrit perfet (passato prossimo) i l'aspecte lèxic dels SV s’ha investigat en el context de la producció i comprensió dels temps compostos perfectius. Els resultats mostren que els nens no utilitzen el pretèrit perfet amb tots els verbs com els adults: la informació aspectual codificada en el SV, tant la que afecta el significat estructural vinculat a la projecció dels objectes com la que afecta el significat idiosincràtic de l'arrel verbal, influeix en la comprensió infantil de la morfologia aspectual perfectiva fins a l'edat de 7 anys. Les principals conclusions d'aquest treball mostren que les relacions en la interfície sintaxi-semàntica ja estan ben establertes quan els nens produeixen els primers verbs i tenen influència en la distribució dels arguments implícits, en la posició oracional dels arguments explícits i en la interpretació aspectual. Si bé no podem determinar si l’adquisició dels primers verbs està desencadenada per la representació sintàctica o semàntica, sí que podem argumentar que tant els significats estructurals com els idiosincràtics que estan codificats en els SV estan actius en les diferents etapes de l'adquisició d'una llengua.
An issue in the study of language acquisition that has attracted much attention is the nature of early verbs. At around the age of 2, children start to combine words and to produce the first verbs. Verbal items appear later than nouns and refer to the relational concepts in the world that are represented in syntax through the argument structure. This dissertation aims to examine the features of the first verbal productions in Italian. Since the appearance of verbs implies the mastery of a procedure of mapping between syntactic positions and semantic roles, the topic under examination has consequences not only for the description of the timeline of the acquisition of the lexicon, but also for the definition of a general model of the interface between syntax and lexical semantics in the early stages. The proposal is that syntactic-semantic features are at work early in child grammar in determining the clausal derivation. Verbs involve structural and idiosyncratic meaning: while structural meaning is derived by the few syntactic frames (number and features of the arguments) which a verb can appear in, idiosyncratic meaning is given by the relations in the world that each verbal root denotes. The architecture of the syntax-semantics interface for verbs implies a mapping procedure from few syntactic frames to many relations in the world and/or vice versa. The structural meaning of early verbs is explored through an analysis of the distribution of the overt arguments and the auxiliaries in a corpus of spontaneous speech of children and adults. The results will show that the lexical classes of verbs influence the distribution of null subjects and the choice of the position in which the subjects are expressed in the sentences. Verb classes also seem at work in the selection and the distribution of the auxiliaries: children properly select auxiliaries depending on the lexical-syntactic information encoded in the VP layer. At the age of the appearance of the first verbs, children are simultaneously learning the syntactic derivations that involve the IP and the CP layers. Some differences between child and target grammar are found in the syntactic domains used for the spell-out at syntax-phonology interface: a lower initial spell-out domain may disfavor the derivations to high clausal positions where scope discourse semantic features like Topic and Focus are checked. Two experimental tasks are designed to observe the effects of the presence of an overt object in the VP in determining the aspectual reading. The interaction between the perfective aspect encoded in the present perfect (passato prossimo) and the lexical aspect of the VPs is investigated in the production and comprehension of perfective compound tenses. The results show that children do not use the present perfect with all verbs like adults: the aspectual information encoded in the VP, both the structural meaning linked to the projection of the objects and the idiosyncratic meaning of the verbal root, influences children’s understanding of aspectual perfective morphology till the age of 7. The main conclusions of the present work show that the relations at syntax- semantics interface are already well established when the first verbs are uttered by children and influence the pattern of distribution of overt/null arguments, the clausal derivation to scope-discourse semantic position, and the aspectual interpretation. While we cannot determine whether the first verbs are bootstrapped by the semantic or the syntactic representations, we can argue that both the structural and idiosyncratic meanings encoded in the VPs are at work in the different stages of acquisition of a language.

La formation et l’évolution de la phase métal dans les corps primitifs et les planétésimaux sont d’une importance majeure pour comprendre les premières étapes de l’évolution du Système Solaire primitif. Malgré de nombreuses études sur le métal des chondrites, les conditions de condensation à température intermédiaire, et les processus de chauffe et d’oxydation qui l’affectent dans le disque d’accrétion et dans les planétésimaux sont toujours mal compris. En utilisant une approche combinée des mesures in situ des éléments fortement sidérophiles (HSE) et modérément sidérophiles (MSE) et volatils (e.g. germanium), ainsi que de la composition isotopique du germanium du bulk et des phases séparées des chondrites, cette thèse vise à apporter des contraintes supplémentaires quant à : (1) la formation du métal via condensation et la fusion de précurseurs métalliques dans les chondrites carbonées de type CB (Bencubbinites), (2) l’évolution du métal avec le métamorphisme enregistrée dans la séquence H, L et LL des chondrites ordinaires. Le fractionnement isotopique du germanium permet de distinguer les deux groupes de chondrites carbonées CB et de tracer différentes étapes de condensation à l’équilibre et cinétique, et d’évaporation. Ces processus ne peuvent être enregistrés par les éléments majeurs et réfractaires (Fe, Ni) dont la température de condensation est plus élevée que celle du germanium. Dans le métal des chondrites ordinaires primitives (type H), les larges variations en éléments sidérophiles, ainsi que les valeurs positives du Δ74/70Gemetal-silicate, suggèrent des variations locales de l’état d’oxydation et des échanges métal-silicate, lors du métamorphisme sur les corps parents. Un des résultats majeurs est l’augmentation corrélée des valeurs δ74/70Ge et des anomalies isotopiques de l’oxygène Δ17O et %Fa dans la séquence H, L à LL des chondrites ordinaires. Ces observations sont interprétées et modélisés par l’accrétion graduelle d’un composant oxydant avec une composition élevée en δ74/70Ge et Δ17O des groupes H, à L et LL durant la formation des chondrites ordinaires. Ce composant à la fois riche en eau et en Ge pourrait être identifiée comme un phyllosilicate. Les conclusions de cette thèse soulignent le fort potentiel des isotopes du germanium pour enregistrer les processus de formation et d’évolution de la phase métal
The formation and subsequent chemical evolution of FeNi metal phases is critical for understanding the development of the early Solar System. Despite numerous studies on metal phases in chondrites, the effect of metal condensation at moderate temperatures, as well as of metal heating and oxidation in nebular and protoplanetary environment, is still under debate. By using a combined approach of germanium isotopic quantification and siderophile in–situ measurements in bulk and separated phases of Bencubbinites carbonaceous chondrites (CB) and ordinary chondrites, this thesis aims to provide new constraints on: (1) the formation of metal via condensation and metallic precursors melting and (2) the processes that can account for the elemental and isotopic difference between the H, L and LL chondrites and metal evolution with metamorphism. The results show that the two groups of CB are distinguishable using δ74/70Gebulk, providing insights into kinetic and equilibrium condensation processes. Variations in δ74/70Ge during metal condensation are shown to be the result of evaporation / recondensation processes that are not recorded by major or refractory elements. A large variation in siderophile element content in the metal of H primitive ordinary chondrites has been identified, as well as a positive Δ74/70Gemetal–silicates. This suggests local oxidation state variation and metal–silicate interactions during heating event(s) in the disk. The thesis also highlights that the H, L and LL groups are resolvable with δ74/70Ge of bulk and metal. These variations are positively correlated with Δ17O and %Fa across the ordinary chondrites sequence and suggests the accretion of an increasing proportion of oxidising components with a high δ74/70Ge and Δ17O composition from H to L to LL groups. Because the oxidising component contains Ge it suggests that it cannot be ice or water but more likely a silicate phase. These conclusions highlight the high potential of germanium isotopes to record processes leading to metal formation and evolution

La Terre s'est formée il y a 4,5 milliards d'années par accumulation de poussières, de roches et de gaz. La composition de ces matériaux primitifs est aujourd'hui enregistrée dans les météorites. Cependant, l'origine des éléments volatils présents dans l'atmosphère (e.g., H, C, N, O) reste incomprise. En combinant des approches expérimentales à l'étude d'échantillons naturels, je me suis intéressé aux objets célestes contenant les ingrédients nécessaires à la formation de l'atmosphère terrestre. Il s'agit principalement des éléments volatils contenus dans la matière organique des météorites et dans la glace des corps cométaires. Afin de reconstituer l'histoire de formation de la Terre et de son atmosphère, j'ai utilisé les gaz nobles (He, Ne, Ar, Kr, Xe) comme traceurs des processus physiques ayant eu lieu dans le Système Solaire jeune et sur la Terre primitive. Bien que les comètes aient significativement contribué à l'apport des gaz nobles lourds de l'atmosphère (~20%), la majorité des autres éléments volatils terrestres (incluant l'eau, le carbone et l'azote) aurait été apportée par des corps dits "chondritiques", similaires aux météorites. Une fois formée, l'atmosphère a évolué au cours des temps géologiques, conduisant à l'établissement des conditions environnementales propices au développement de la vie. Les processus majeurs ayant affecté la masse et la composition de l'atmosphère ancienne se reflètent dans l'évolution isotopique du Xe atmosphérique, de 4.5 Ga à ~2 Ga. Nous étudions la possibilité d'apporter des contraintes sur l'âge des matériaux organiques retrouvés dans les roches sédimentaires plus anciennes que 2 Ga, en utilisant la signature isotopique du Xe qu'ils ont piégé au moment de leur formation. Cette méthode pourrait avoir des implications vis-à-vis de l'âge présumé des plus anciennes traces de vie organique
The Earth formed some 4.5 Ga from the accumulation of dust, rocks and gas. The composition of these primitive materials is today recorded in meteorites. However, the origin of volatile elements within the atmosphere (e.g., H, C, N, O) remains poorly understood. By combining experimental approaches and the analysis of natural samples, I studied the composition of celestial objects comprising the ingredients required for the formation of the terrestrial atmosphere. These mainly correspond to volatile elements trapped in meteoritic organic materials and in the ice of cometary bodies. In order to better understand the timeline of Earth's formation and volatile accretion, I used noble gases (He, Ne, Ar, Kr, Xe) as tracers of the physical processes that occurred in the early Solar System and on primitive Earth. Whilst comets significantly contributed to the heavy noble gas budget of the terrestrial atmosphere (~20%), most of the other terrestrial volatile elements (including water, carbon and nitrogen) would have been supplied to Earth by chondrtitic bodies similar to meteorites. Once formed, the atmosphere evolved over geological periods of time, leading to the establishment of suitable environmental conditions for life to develop. The major processes that affected the mass and composition of the ancient atmosphere can be studied by investigating the isotopic evolution of atmospheric Xe, from 4.5 Ga to ~2 Ga. We investigate the possibility to bring constraints on the age of organic materials isolated from sedimentary ricks older than 2 Ga, using the isotopic signature of the Xe component that was trapped at the time of their formation. This method could have implications regarding the presumed age of the earliest remnants of organic life

Jusqu’à peu, Mars était vue comme une planète à substrat crustal homogène, dominé par des basaltes à olivine. Les missions in situ ont contribué à bouleverser cette vision si simpliste. Le rover Curiosity qui sillonne le cratère d’impact de Gale formé à l’Hespérien (3.5-3.8 Ga) creusé dans des roches noachiennes (> 3.8 Ga), a ainsi découvert, grâce aux analyses LIBS (‘laser induced breakdown spectroscopy’) de l’instrument ChemCam, des roches ignées alcalines felsiques noachiennes, révélant un magmatisme primitif évolué (Sautter et al., 2016) : ce résultat est en accord avec l’identification récente de clastes ignés felsiques d’âge Noachien observés dans la brèche martienne NWA 7533 et ses paires. Une croûte primitive martienne évoluée de type ‘continentale’ aurait-elle existé ? C’est ce que suggère ce travail de par l’observation orbitale GRS de plusieurs terrains noachiens felsiques enrichis en K et Th et abondants en feldspaths. Par ailleurs, du fait de l’identification de feldspaths peu calciques dans les roches et clastes de Gale et de la brèche, il est envisagé ici que la croûte primitive martienne ait pu se former selon un modèle différent de l’océan de magma défini sur la Lune. De plus, la quantification de Li, Rb, Sr et Ba dans l’ensemble des matériaux ignés de Gale analysés par la LIBS ainsi que leurs concentrations dans les clastes ignés de la brèche, suggèrent l’existence de plusieurs réservoirs magmatiques primitifs. En parallèle, la quantification du Cu à partir des données LIBS effectuée dans cette étude, met en évidence des abondances anormalement élevées dans des roches potassiques de la région de Kimberley. Majoritairement associées à des silicates détritiques ignés, ces phases de cuivre proviendraient d’une source magmatique primitive siliceuse localisée dans le flanc Nord de Gale. Au Noachien, la circulation hydrothermale dans un magma évolué aurait formé un gisement métallifère de cuivre aux alentours du cratère. Finalement, la Terre et Mars sont géologiquement plus proches que jamais
Until recently, Mars was considered as a planet with a homogeneous crust dominated by olivine-rich basalts. This simplistic vision has been largely disrupted especially with results of recent in situ missions. In this way, the Curiosity rover that travels in Gale crater, which formed by impact during the Hesperian period (3.5-3.8 Gyr) within igneous basement rocks dated at 4.2 Gyr, discovered Noachian alkaline igneous rocks (> 3.8 Gyr) using the ChemCam LIBS instrument (‘laser induced breakdown spectroscopy’): this observation along with the recent identification of Noachian igneous felsic clasts within the breccia meteorite NWA 7533 and subsequent paired stones, revealed an evolved primitive magmatic system (Sautter et al., 2016). Would an evolved ‘continental’ primitive crust have ever existed on Mars? This is favored in this work by orbital GRS observations showing several Si-K-Th-rich Noachian terrains displaying abundant feldspars. Besides, the identification of low-Ca feldspars within the clasts of the breccia and Gale rocks, suggests that the primitive martian crust may have formed according to a model that differs from the lunar magma ocean. In addition, the LIBS quantification of Li, Rb, Sr and Ba presented in this work in igneous rocks, along with the distribution of alkali trace elements within the igneous clasts of the breccia, suggests the potential occurrence of several magmatic reservoirs. Concurrently, in the Kimberley formation, copper quantification using LIBS data, reveals anomalously elevated abundances within potassic rocks: these Cu-phases mainly associated with detrital igneous silicates, would come from a primitive felsic igneous source located in the northern rim. During the Noachian period, the hydrothermal circulation within an evolved magmatic chamber favored the formation of a Cu-bearing deposit in Gale vicinity. After all, the Earth and Mars are geologically closer than ever

Les cherts, roches siliceuses, sont souvent considérés comme des marqueurs des conditions environnementales de la Terre primitive. Ces roches sont constituées de quartz sous différentes formes dont le quartz microcristallin ou microquartz est la forme majoritaire. Le but de cette thèse est d'étudier à l'échelle micrométrique les compositions isotopiques de l'oxygène et du silicium des différentes formes de silice dans des cherts d'âges variés, allant de 3,5 à 1,9 Ga afin de mieux comprendre l'origine et le mode de formation de ces roches et d'essayer d'améliorer les reconstructions des températures océaniques du Précambrien. Les mesures isotopiques, réalisées à la sonde ionique ims 1270, ont une précision meilleure que 0,2 ‰ pour le [delta]18O et de l'ordre de 0,3 ‰ pour le [delta]30Si. Ces analyses isotopiques ont été combinées avec l'analyse des éléments traces (B, Na, Mg, Al, K, Ca, Ti, Fe) avec la sonde ionique 3f, avec une étude pétrographique détaillée du microquartz et avec l'analyse des inclusions fluides des veines de quartz. Le résultat principal est la mise en évidence de grandes gammes de variation du [delta]18O (entre 1 ‰ et 14?‰) et du [delta]30Si (entre 2 ‰ et 5 ‰) à l'échelle micrométrique dans le microquartz. La gamme de variation du [delta]18O a pu être interprétée dans les échantillons datés de 1,9 Ga comme témoignant de l'histoire diagenètique de ces roches. Cette gamme permet, en corrigeant de l'effet de la diagenèse, de reconstruire des températures océaniques à 1,9 Ga entre 37 et 52°C, ce qui laisse suggérer un océan assez chaud au Précambrien si ces échantillons sont représentatifs de conditions globales. Dans le cas des échantillons datés à 3,5 Ga, les variations de [delta]30Si et de concentrations en éléments traces apportent des informations sur les origines variées des cherts. Enfin, l'effet des circulations fluides sur les compositions isotopiques du microquartz a été caractérisé par l'analyse isotopique du [delta]18O et du [delta]30Si et par l'étude des inclusions fluides. Il est démontré que dans certains cas le [delta]18O du microquartz peut être entièrement rééquilibré avec les fluides hydrothermaux ou métamorphiques. L'approche développée dans cette thèse devra dans le futur être appliquée systématiquement à l'étude des cherts aux fins de reconstructions paléo-environnemantales
Cherts, which are siliceous rocks, are considered as possible proxies of paleo-environmental conditions of the Early Earth. These rocks contain various forms of quartz, microquartz being the predominant one. The study of oxygen and silicon isotopic composition in the various forms of silica in cherts of different ages, from 3,5 Ga to 1,9 Ga, allowed to better understand the origin and the formation of these rocks and allowed to try to reconstruct paleo-temperatures for Precambrian seawater. Isotopic measurements were obtained with the ims 1270 multicollector ion microprobe with a precision better than 0,2 ‰ for [delta]18O and of ˜ 0,3 ‰ for [delta]30Si. These analyses were combined with the measurement of traces elements concentrations (B, Na, Mg, Al, K, Ca, Ti, Fe) with the ims 3f ion microprobe, with a petrographical study of microquartz and with the study of fluid inclusions in quartz veins. The major result is the existence at a micrometer scale of a large range of variations for [delta]18O (between 1 ‰ to 14?‰) and [delta]30Si (between 2‰ to 5‰). In the Gunflint cherts, the range of [delta]18O variation has been interpreted as due to diagenesis and has been used to reconstruct oceanic paleo-temperatures. The calculated temperatures range from +37°C to +52°C, suggesting an hot ocean during the Precambrian era if Gunflint cherts are representative of global environmental conditions. The [delta]30Si variations associated with that of trace elements concentrations allow to constrain the various origins of these cherts. The effect of fluid circulations on the isotopic compositions has been characterized by [delta]18O and [delta]30Si analyses and by fluid inclusions study. It is shown that in some cases the [delta]18O value of microquartz can be totally re-equilibrated with the hydrothermal or metamorphic fluids. The approach developed in this thesis will be decisive in future studies of Archean cherts for paleotemperature reconstructions

Orientador: Antonio Paques
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
Made available in DSpace on 2018-08-03T19:13:26Z (GMT). No. of bitstreams: 1 Bagio_Dirceu_D.pdf: 448817 bytes, checksum: 160c3b2a0ae39e2870be16fd08c01a85 (MD5) Previous issue date: 2004
Resumo: Um dos teoremas clássicos da teoria de Galois para corpos é o teorema do elemento primitivo. Na teoria de Galois para anéis comutativos com unidade, tal teorema não é válido em geral. Nesse trabalho encontramos condições necessarias e suficientes para a existencia de elemento primitivo para uma extensão fortemente separavel de um anel comutativo com unidade e cujos unicos idempotentes são os triviais. Além disso, apresentamos uma forma fraca deste teorema e provamos que esta forma fraca é valida para anéis conexos cujo quociente pelo radical de Jacobson é von Neumann regular e localmente uniforme. Analisamos também o fecho separável de um anel comutativo conexo. Obtemos alguns resultados que relacionam, em particular, o fecho separável do anel com o fecho separável de cada um de seus corpos residuais
Abstract: One of the classic theorems of the Galois theory of fields is the ¿Primitive Element Theorem¿. In Galois theory of commutative rings, such a theorem does not hold, in general. In this work we give necessary and sufficient conditions for the existence of a primitive element in an strongly separable extension of a connected commutative ring. Furthermore we present a weak form of the Primitive Element Theorem and we prove that this theorem holds for strongly separable extensions of connected commutative rings whose quotient by its Jacobson radical is a von Neumann regular and locally uniform ring. We also obtain some new results about the separable closure of a connected commutative ring. In particular, we describe a relation between the separable closure of such a ring and the separable closure of each one of its residual fields
Doutorado
Doutor em Matemática

Les abondances en éléments sidérophiles du manteau terrestre indiquent une ségrégation du noyau dans un océan magmatique profond. Il est néanmoins difficile de contraindre les conditions d’oxydation prévalant lors de l’accrétion planétaire, en se basant sur les traceurs géochimiques, en raison du nombre important de paramètres qui affectent leurs partages entre métal et silicate. D’autre part, l’état d’oxydation des planètes peut évoluer au cours de l’accrétion. Par conséquent, la nature des matériaux accrétés lors de la formation des planètes reste incertaine. Afin d’apporter de nouveaux éléments de réponses à cette problématique, nous avons modélisé les équilibres chimiques ayant lieu dans la Terre primitive. Ces équilibres peuvent évoluer (i) en augmentant les conditions de pression et de température de la ségrégation du noyau lors de la croissance de la planète, (ii) en raison de la cristallisation de l’océan magmatique et (iii) à travers l’accrétion de matériaux hétérogènes de compositions et états redox différents. Nous avons exploré le rôle potentiel de l’érosion collisionnelle dans le contexte de l’accrétion de la Terre à partir de chondrites à enstatite. Pour cela, nous avons déterminé expérimentalement les compositions chimiques des liquides pseudo-eutectiques en fonction de la pression jusqu’à 25 GPa. Nous avons montré que ces premiers liquides sont très enrichis en SiO2 (jusqu’à 75 wt% SiO2) et en éléments alcalins (Na et K). Par conséquent, l’érosion collisionnelle de proto-croutes de planétésimaux formés de chondrites EH peut de manière efficace augmenter le rapport final Mg/Si du manteau terrestre et réduire ses concentrations en éléments alcalins volatils. Ce mécanisme peut donc concilier les différences compositionnelles entre la Terre et les chondrites à enstatite. Nous avons également déterminé expérimentalement le partage du soufre entre métal riche en fer et silicate. La concentration en soufre du manteau terrestre peut être expliquée par un équilibre entre manteau et noyau dans un océan magmatique profond. L’hypothèse de l’ajout de soufre dans un vernis tardif (Rose-Weston et al., 2009) n’est pas à exclure, mais il n’est pas indispensable pour atteindre la concentration en soufre du manteau. Ces résultats sont en accord avec les compositions isotopiques non chondritiques du soufre dans le manteau (Labidi et al., 2013). Le partage des éléments légers (S, Si, O) entre manteau et noyau a été modélisé à hautes pressions et températures en prenant compte de leurs interactions chimiques mutuelles et celles avec le carbone. En considérant 2 wt% S et jusqu’à 1.2 wt% C (comme il est suggéré par les études cosmochimiques), nous trouvons une solubilité de l’O comprise entre 1 et 2.4 wt%. Cette insertion de l’O dans le noyau n’est pas suffisante pour permettre à la Terre d’être à la fois accrétée de matériaux météoritiques oxydés et de posséder un noyau métallique d’une masse équivalente au tiers de la planète ainsi que 8 wt% FeO dans le manteau. Des conditions relativement réduites lors de la ségrégation du noyau sont également requises pour augmenter le taux de Si dans le noyau et expliquer le rapport Mg/Si super-chondritique de la Terre silicatée (Allègre et al., 1995; O’Neill et al. 1998). Ainsi, la Terre s’est plus probablement accrétée à partir de matériaux réduits comme les chondrites à enstatites, conduisant à un noyau constitué de 2 wt% S, 0 à 1.2 wt% C, 1 wt% O et 5.5 à 7 wt% Si. Nous avons également exploré le comportement du Fe lors de la cristallisation de la pérovskite magnésienne (le minéral le plus abondant du manteau terrestre) et son rôle sur l’état redox du manteau terrestre lors du refroidissement de l’océan magmatique. Nous avons montré que sa cristallisation induit une diminution du FeO dans le manteau solide, lors d’un équilibre avec un alliage de fer liquide à une fO2 de IW-2 en raison du caractère incompatible du Fe dans la pérovskite. (...)
Abundances of siderophile elements in the mantle indicate that the Earth’s core segregated in a deep magma ocean. Yet, it is unfortunately difficult to constrain the oxidation conditions prevailing during planetary accretion based on geochemical tracers due to the number of parameters playing a role in metalsilicate partitioning. In addition, the oxidation state of terrestrial planets can evolve during accretion. The nature of the accreted material during the formation of the terrestrial planets remains then still uncertain. Our strategy to improve our knowledge in this domain is to model the chemical equilibria taking place in the primitive Earth. The equilibria can evolve (i) as P-T conditions of core-mantle segregation increase with the size of the planet, (ii) due to crystallization of the magma ocean and (iii) with accretion of heterogeneous material of different composition and oxidation state. We explored the potential role of collisional erosion in the context of Earth’s accretion from Enstatite Chondrites. For this, we refined experimentally the chemical composition of pseudo-eutectic melts as a function of pressure up to 25 GPa. We show that the first melts are highly enriched in SiO2 (up to 75 wt% SiO2) and alkali elements (Na and K). Therefore, collisional erosion of proto-crusts on EH-planetesimals can efficiently increase their final Mg/Si ratio and decrease their alkali elements budget. It can help to reconcile compositional differences between bulk silicate Earth and Enstatite Chondrites. We performed new experiments on metal-silicate partitioning of sulphur. We show that the present-day sulphur concentration of the Earth’s mantle can be explained by core-mantle equilibration in a deep magma ocean. S-addition in a late veneer (Rose-Weston et al., 2009) cannot be excluded; however, it is not required in order to reach the S-mantel abundance. Our results are consistent with the non-chondritic S-isotopic nature of the mantle (Labidi et al., 2013). We modeled the core-mantle partitioning of the light elements (S, Si, O) at high pressures and temperatures, by taking into account of their mutual chemical interactions and that with C. With 2 wt% S in the core and a C concentration ranging 0 to 1.2 wt% (as evidenced with cosmochemical studies), we found the O solubility from 1 to 2.4 wt%. This O incorporation to the core is insufficient to both allow an Earth accretion from an oxidized meteoritic material and result in a planet composed of a core with a mass equivalent to the third of its mass and a mantle with 8 wt% FeO content. Reduced conditions during coremantle segregation are also required to enhance the Si content in the core, possibly up to 5 wt% Si, to explain the super chondritic Mg/Si of the bulk silicated Earth (Allègre et al., 1995; O’Neill et al. 1998). Altogether, we find that the Earth was most likely accreted from a reduced material, such as enstatite chondrites, leading to a core composed of 2 wt% S, 0 to 1.1 wt% C, 1 wt% O and 5.5 to 7 wt% Si. We investigated the role of Mg-perovskite (the most abundant mineral of the mantle) crystallization on the oxidation state of Earth’s mantle during cooling of the magma ocean. We show that its crystallization induces a decrease of FeO content of the solid mantle as Fe is incompatible in perovskite, when it is in equilibrium with a liquid Fe-alloy at an fO2 of IW-2. At these conditions, the Fe3+ insertion is also low and constant (Fe3+/ Fetot of 21 ±4 %). Hence, the Mg-Pv crystallization cannot be responsible for a substantial increase of the Earth’s mantle oxygen fugacity during core segregation. (...)

Neste trabalho apresentamos várias demonstrações do Teorema da Base Normal para certos tipos de extensões galoisianas de corpos, algumas existenciais e outras construtivas, destacando as diferenças e dificuldades de cada situação. Apresentamos também generalizações de tal teorema e mostramos que toda extensão galoisiana de grau ímpar de corpos admite uma base normal autodual com respeito µa forma bilinear traço
In this work we present several demonstrations of The Normal Basis Theorem for certain kinds of galoisian extensions of fields, some of them existential and others constructive, pointing the diffculties and differences in each situation. We also present generalizations of such theorem and show that every odd degree galoisian extension of fields admits a self-dual normal base with respect to the trace bilinear map

Made available in DSpace on 2016-04-26T18:17:11Z (GMT). No. of bitstreams: 1 Priscila Goncalves Magossi.pdf: 313138 bytes, checksum: 6a4f37f763065065bd4ccaf83514dec0 (MD5) Previous issue date: 2008-05-08
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The research is dedicated to the study and applications of some ritual elements in the mass media, as an attempt to fulfill the emptiness of existence, occasioned by the arrival of consciousness in the primordial man. Justification for this topic is based on the perception that the primitive man, with his mythic thoughts, and the modern man, straight thoughts formulated, have the same collective ritual dimensional base. Ritual must be read as a group of actions defined by their symbolic importance to a specific society. The actions and symbols aren't freely chosen by individuals, they are imposed by an external source. For the primordial man, the source is the ceremonial priests. For the modern man, the source is the influence of mass media. Showing how media uses the archetypical and sacred aspect of the ritual, manipulating its core for their own needs and satisfaction: fascination, enchantment, infiltration and stereotyping. By the Cultural Semiotic prism, the thesis aspires to contribute to studies and cultural communication, aiming for the rescue of complexity in the means of communication. How primitive rituals formats still survive in modern media, albeit in a saturated way, is the question this study addresses. Adopted methodological procedure was a research of qualitative character, involving analysis and bibliographical survey. As the theorical board of references are the authors B. Cyrulink, D. Kamper, E. Morin, H. Pross, I. Bystrina, J. Hillman, K. Lorenz, M. Berman, M. S. Contrera, N. Baitello Jr., N. Sevcenko, V. Flusser, V. Romano e Z. Bauman. The conclusion is that, even if banalized and distorted, the principles of symbolic reorganization of the ritual still exert considerable influence in the media and in the mindset of the modern man
A pesquisa está dedicada ao estudo da aplicação de alguns elementos rituais pela mídia de massa, como tentativa de suprir o vazio existencial, proporcionado pelo surgimento da consciência no homem genérico. A justificativa da escolha do tema repousa na percepção de que tanto o homem primitivo, com sua estrutura de pensamento mítico, quanto o homem atual, com seu pensamento linearmente formulado, alimentam-se do ritual de dimensão coletiva. Entende-se por ritual um conjunto de ações, caracterizadas por seu valor simbólico, para determinado grupo social. Tanto as ações quanto o simbolismo não são escolhidos livremente pelo indivíduo, mas ditados por uma fonte externa. No caso do homem primordial, a fonte relaciona-se aos mestres da cerimônia religiosa. No caso do homem atual, a fonte refere-se ao poder de influência da mídia de massa. Nesse sentido, a intenção do trabalho de pesquisa é mostrar como a mídia utiliza o recurso arquetípico e sagrado do ritual, transportando seu núcleo de sentido para a satisfação dos seus interesses imediatos: fascínio, encanto, infiltração e estereotipagem. Sob a vertente da Semiótica da Cultura, a dissertação objetiva contribuir para os estudos de comunicação e cultura, visando o resgate da complexidade nos meios de comunicação. O problema de pesquisa diz respeito à questão de como o formato do ritual primitivo sobrevive, de modo saturado, nos meios de comunicação de massa, e de que modo lhes foi incorporado. Referente às questões metodológicas, o procedimento adotado foi uma pesquisa de caráter qualitativo, envolvendo crítica e levantamento bibliográfico. Para estabelecer a relação desejada entre conteúdo arcaico e mídia de massa foram selecionadas como referencial teórico a semiótica da cultura (centradas nos autores I. Bystrina, M. S. Contrera e N. Baitello Jr), a teoria da comunicação (de B. Cyrulink, K. Lorenz, V. Flusser e V. Romano), as teorias da mídia e do imaginário (baseadas nos textos de D. Kamper e H. Pross), entre outras áreas do conhecimento e outros autores, tais como, E. Morin, J. Hillman, M. Berman, N. Sevcenko e Z. Bauman. A conclusão do estudo foi a de que, apesar de distorcido e banalizado, os princípios de reorganização simbólica do ritual continuam a exercer notável influência na mídia e na mentalidade do homem atual

Cette thèse est consacrée à l'histoire des solides du système solaire primitif. Nous étudions la dynamique des composants chondritiques et trouvons que leur préservation pendant plusieurs Ma dans le disque protoplanétaire nécessite une zone morte. Cette dynamique est essentiellement gouvernée par un paramètre de découplage gaz-solide S que nous conjecturons avoir été <1 et >1 lors de l'accrétion des chondrites carbonées et non carbonées, respectivement. Nous étudions aussi des modèles réduits pour l'interaction entre la turbulence magnétohydrodynamique et la sédimentation de la poussière ainsi que l'instabilité d'écoulement linéaire. Nous mesurons la concentration d'éléments en trace dans les phases des chondres dans Vigarano, Renazzo, Acfer 187, Bishunpur et Sahara 97096. L'olivine dans les chondres de type I semble résulter d'une cristallisation à l'équilibre tandis que le pyroxène enregistre des taux de refroidissement rapides et est compatible avec une interaction gaz-liquide.

No presente trabalho estudam-se diferentes técnicas explícitas, em diferenças finitas, no emprego de algoritmos do tipo velocidade-pressão para simulação de escoamentos incompressíveis. O método de resolução da pressão de maneira direta e explícita, introduzido por Bravo e Claeyssen [BRA 97a], é analisado. Faz-se uma aproximação para o erro causado por esta técnica, e verifica-se como isto afeta a equação da continuidade. As simulações são realizadas na cavidade quadrada, comparando-se os diferentes métodos e validando as aproximações realizadas no estudo do método de resolução da pressão. Além disso, simula-se o escoamento em cavidades profundas e rasas, observandose a formação de vórtices e distribuição de energia cinética. Simulações do escoamento na cavidade cúbica também são apresentadas.
In this work different explicit technics in finite defferences in the application of velocity-pressure algorithm to simulate incompressible flows have been studied. The direct and explicit method of pressure resolution, introduced by Bravo anel Claeyssen [BRA 97a] is analyzed. An approximation to the error caused by this method is made, anel how this affects the continuity equation is verified. The simulations are maele in a square cavity, comparing the differents methoels anel valielating the approximations maele in the study of the pressure resolution method. Besieles this, flow in eleep and shallow cavities is simulateel, observing the formation of vortices and kinetic energy distribution. Simulations of the flow in the cubical cavity are also considered.

As the solar nebula condensed, evaporated and fractionated to form the nascent Earth, the bulk elemental composition of the Earth was established. To first order, the Earth is a devolatilized sample of the solar nebula. Similarly, rocky exoplanets are also likely devolatilized samples of the stellar nebulae out of which they and their host stars formed. If this assumption holds, we can estimate the chemical composition of rocky exoplanets by applying a devolatilization algorithm based on the elemental abundances of their host stars. This thesis is an investigation of this potentially universal devolatilization pattern, from which exoplanetary chemistry and habitability are then derived. To quantify (in broad terms) the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. The key to comparing Earth’s composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of un- certainties. We present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, by compiling, combining, and renormalizing a large set of heterogeneous literature values of the primitive mantle and of the core. The weighting factor for the concordance estimates comes from our new estimate of the core mass fraction of the Earth: 32.5±0.3 wt% (weight percent). The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models made under various geochemical and geophysical assump- tions. We then extend our assessment of terrestrial abundances to the modeling of pro- tosolar abundances based on the latest estimates of solar photospheric abundances and primitive meteoritic abundances. We compare our new protosolar abundances with our estimates of bulk Earth composition, thereby quantifying the devolatiliza- tion of the solar nebula that led to the formation of the Earth. As a function of elemental 50% condensation temperatures (TC), we fit the Earth-to-Sun abundance ratios f to the linear trend log( f ) = a log(TC ) + b. The best fit coefficients are: a = 3.676 ± 0.142 and b = 11.556 ± 0.436. The quantification of the slope a provides an empirical observation upon which modeling of the devolatilization processes can be based. These coefficients determine a critical devolatilization temperature for the Earth TD(E) = 1391 ± 15 K. The resultant devolatilization pattern allows inferences to be made concerning the depletions of elements in the early solar system and is potentially useful for estimating the chemical composition of rocky exoplanets from their known host stellar abundances. We apply the devolatilization pattern to nearby planetary systems to infer the bulk elemental composition of rocky exoplanets – particularly those within the cir- cumstellar habitable zones – from the known host stellar elemental abundances. The estimated bulk planetary composition (rather than the host stellar abundances) is then used as a principal constraint to model the interior composition and structure of such exoplanets. We apply these constraints to four planet host stars: Kepler-10, Kepler-20, Kepler-21 and Kepler-100, to model the interiors including the mantle and core compositions as well as core mass fraction for potential terrestrial exoplanets orbiting these host stars. With respect to the estimates of the interiors, we conclude that a potential terrestrial exoplanet orbiting Kepler-21 would be the most Earth-like while one orbiting Kepler-10 would be the least.

Background: MPLC represents a diagnostic challenge. Topic of the discussion is how to distinguish these patients as a metastatic or a multifocal disease. While in case of the different histology there are less doubt on the opposite in case of same histology is mandatory to investigate on other clinical features to rule out this question. Matherials and Methods: A retrospective review identified all patients treated surgically for a presumed diagnosis of SPLC. Pre-operative staging was obtained with Total CT scan and fluoro-deoxy positron emission tomography and mediastinoscopy. Patients with nodes interest or extra-thoracic location were excluded from this study. Epidermal growth factor receptor (EGFR) expression with complete immunohistochemical analisis was evaluated. Survival was estimated using Kaplan-Meyer method, and clinical features were estimated using a long-rank test or Cox proportional hazards model for categorical and continuous variable, respectively. Results: According to American College Chest Physician, 18 patients underwent to surgical resection for a diagnosis of MPLC. Of these, 8 patients had 3 or more nodules while 10 patients had less than 3 nodules. Pathologic examination demonstrated that 13/18(70%) of patients with multiple histological types was Adenocarcinoma, 2/18(10%) Squamous carcinoma, 2/18(10%) large cell carcinoma and 1/18(5%) Adenosquamosu carcinoma. Expression of EGFR has been evaluated in all nodules: in 7 patients of 18 (38%) the percentage of expression of each nodule resulted different. Conclusions: MPLC represent a multifocal disease where interactions of clinical informations with biological studies reinforce the diagnosis. EGFR could contribute to differentiate the nodules. However, further researches are necessary to validate this hypothesis.

Background: MPLC represents a diagnostic challenge. Topic of the discussion is how to distinguish these patients as a metastatic or a multifocal disease. While in case of the different histology there are less doubt on the opposite in case of same histology is mandatory to investigate on other clinical features to rule out this question. Matherials and Methods: A retrospective review identified all patients treated surgically for a presumed diagnosis of SPLC. Pre-operative staging was obtained with Total CT scan and fluoro-deoxy positron emission tomography and mediastinoscopy. Patients with nodes interest or extra-thoracic location were excluded from this study. Epidermal growth factor receptor (EGFR) expression with complete immunohistochemical analisis was evaluated. Survival was estimated using Kaplan-Meyer method, and clinical features were estimated using a long-rank test or Cox proportional hazards model for categorical and continuous variable, respectively. Results: According to American College Chest Physician, 18 patients underwent to surgical resection for a diagnosis of MPLC. Of these, 8 patients had 3 or more nodules while 10 patients had less than 3 nodules. Pathologic examination demonstrated that 13/18(70%) of patients with multiple histological types was Adenocarcinoma, 2/18(10%) Squamous carcinoma, 2/18(10%) large cell carcinoma and 1/18(5%) Adenosquamosu carcinoma. Expression of EGFR has been evaluated in all nodules: in 7 patients of 18 (38%) the percentage of expression of each nodule resulted different. Conclusions: MPLC represent a multifocal disease where interactions of clinical informations with biological studies reinforce the diagnosis. EGFR could contribute to differentiate the nodules. However, further researches are necessary to validate this hypothesis.

abstract: The objective of this research is to develop methods for generating the Tolerance-Map for a line-profile that is specified by a designer to control the geometric profile shape of a surface. After development, the aim is to find one that can be easily implemented in computer software using existing libraries. Two methods were explored: the parametric modeling method and the decomposed modeling method. The Tolerance-Map (T-Map) is a hypothetical point-space, each point of which represents one geometric variation of a feature in its tolerance-zone. T-Maps have been produced for most of the tolerance classes that are used by designers, but, prior to the work of this project, the method of construction required considerable intuitive input, rather than being based primarily on automated computer tools. Tolerances on line-profiles are used to control cross-sectional shapes of parts, such as every cross-section of a mildly twisted compressor blade. Such tolerances constrain geometric manufacturing variations within a specified two-dimensional tolerance-zone. A single profile tolerance may be used to control position, orientation, and form of the cross-section. Four independent variables capture all of the profile deviations: two independent translations in the plane of the profile, one rotation in that plane, and the size-increment necessary to identify one of the allowable parallel profiles. For the selected method of generation, the line profile is decomposed into three types of segments, a primitive T-Map is produced for each segment, and finally the T-Maps from all the segments are combined to obtain the T-Map for the given profile. The types of segments are the (straight) line-segment, circular arc-segment, and the freeform-curve segment. The primitive T-Maps are generated analytically, and, for freeform-curves, they are built approximately with the aid of the computer. A deformation matrix is used to transform the primitive T-Maps to a single coordinate system for the whole profile. The T-Map for the whole line profile is generated by the Boolean intersection of the primitive T-Maps for the individual profile segments. This computer-implemented method can generate T-Maps for open profiles, closed ones, and those containing concave shapes.
Dissertation/Thesis
M.S. Mechanical Engineering 2013

Peridotites occuring in orogenic massifs provide important insights into geochemical processes of the Earth's upper mantle by providing direct evidence of mantle evolution throughout Earth history. It has been previously demostrated (e.g. Medaris et al., 1990, 2005) that the uppermost tectonic unit of the Bohemian Massif - the Gföhl Nappe hosts a variety of peridotites that originated from different sources, including subcontinental lithosphere, suboceanic asthenosphere, and possible ultramafic layered intrusive complex. The Czech peridotites of the Gföhl Nappe has been divided into three groups, defined by Medaris et al. (1999), according to their chemical compositions, identity and relations of the aluminous phases, ortopyroxen compositions and estimated P-T conditions. According to Medaris et al. (2005) "Type I" peridotites - represented by Mohelno and Biskoupky bodies - equilibrated in low P-T regime (recording the highest equilibration temperatures - up to 1335 ⁰C at 29 kbar - among the Gföhl peridotites) consist of spinel peridotite with garnet appearing only at its margins. Peridotites are enclosed in granulites that have been extensively recrystallized mostly at amphibolite-facies conditions. Many studies have been done on this locality and a wide range of mineralogy and P-T histories has...

Defining the timescales of magma storage and ascent beneath active volcanoes is a fundamental tool in volcanological investigation of the last decade to constrain pre-eruptive magmatic processes and magma chamber dynamics, since it is able to provide the basis for volcanic hazard assessment. This Ph.D. project focuses on the investigation of the deep portion of the Campi Flegrei Volcanic District plumbing system (crustal-mantle boundary; ~25 km of depth), in correspondence of which the presence of a possible crystallization zone has been hypothesized on the basis of melt inclusion studies, seismic data interpretations, gravimetric and petrological modelling and experimental data. The Campi Flegrei Volcanic District, which includes the Campi Flegrei and the islands of Ischia and Procida, represents one of the most active volcanic areas in the Mediterranean region and one of the most dangerous volcanic complexes on Earth owing to the intense urbanization of the area. Many petrological, geochemical and geophysical surveys were carried out in the Campania Active Volcanic Area that have helped to define the main architecture and the development of the sub-volcanic system. Nevertheless, the dynamic processes that operate during the earliest, deepest differentiation steps of primitive magmas that fed all Campi Flegrei eruptions are yet poorly constrained. The knowledge of the dynamics and residence and ascent timescales of magma at deep levels, indeed, may be the key to understand the triggering mechanisms of volcanic eruptions, and are essential for understanding the rates at which magmas are supplied to volcanic complexes. In this thesis, the investigation of the kinetic and rheological properties of a K-basaltic magma at Moho depth, together with the partitioning of trace elements between crystal and melts, has allowed to fill some gaps relative to the knowledge of the deep portion of the Campi Flegrei Volcanic District plumbing system, providing magma residence time and ascent timescales, and models for deep magmatic differentiation processes.

The traditional riverside communities of Amazonia are human groups that live mostly from subsistence fishing and populate the Amazon River banks and its tributaries. Such communities use simple and primitive fishing elements in everyday life and they experience deficiencies at various levels since they lack infrastructures. The fishing elements are responsible for the survival of the community and to the fishermen mean their intimacy, their home, the positive energies and life, something that is the extension of the community and without which they do not exist. Thus, the general objective of the investigation sought to understand the relation and the meaning of the fishing elements for the Iri community and vice versa, in this case, its function for everyday life and for the subsistence of this community. The choice of this community was due to the researcher's membership in one of these Amazonian communities, in the case of the Iri Community of the Guajará river, located in the Municipality of Prainha (State of Pará-Brazil). The realization of this study is based on this artistic look for the traditional and primitive objects with another sensitivity, which transported us to the artistic movements of the twentieth century that used the resignification. From the methodological point of view, the study follows a qualitative-descriptive approach based on a theoretical perspective (supported by authors such as Bachelard, Beuys, Clark, Tostes or Salles) and practice, on the production process of fourteen contemporary sculptures between december 2015 and june 2016 in the community, these sculptures in wood, re-signifying certain subsistence fishing elements (canoes, rowing, rod, gourds, bow (cuia), arrow, reed, fishing line, harpoon) of the Iri Community. As a result, the investigation has given us a phenomenological and polysemic resignification of its fishing elements and its transformation into "artistic objects", that allow the identification of the Iri community not only by its inhabitants as well as by the general public