Submitted by Lucas Corrêa (lucasacorrea@hotmail.com) on 2014-12-05T00:50:31Z No. of bitstreams: 1 dissertação lucas corrêa.pdf: 852581 bytes, checksum: 12ca065efa2c5f8f924def0300d71a7f (MD5) / Approved for entry into archive by Rafael Aguiar (rafael.aguiar@fgv.br) on 2015-01-06T17:33:03Z (GMT) No. of bitstreams: 1 dissertação lucas corrêa.pdf: 852581 bytes, checksum: 12ca065efa2c5f8f924def0300d71a7f (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2015-01-07T17:23:13Z (GMT) No. of bitstreams: 1 dissertação lucas corrêa.pdf: 852581 bytes, checksum: 12ca065efa2c5f8f924def0300d71a7f (MD5) / Made available in DSpace on 2015-01-07T17:24:59Z (GMT). No. of bitstreams: 1 dissertação lucas corrêa.pdf: 852581 bytes, checksum: 12ca065efa2c5f8f924def0300d71a7f (MD5) Previous issue date: 2014-08-29 / CORRÊA, Lucas Andrade Sá. Um nome e um programa: Érico Sachs e a Política Operária. Esta dissertação pretende discutir a trajetória do militante marxista Érico Sachs. Austríaco, nascido em 1922, Érico chegaria ao Brasil em 1939, após viver na Áustria, União Soviética e França. Em 1961, Sachs seria um dos fundadores da Organização Revolucionária Marxista – Política Operária (ORM-POLOP). A ORM-POLOP ocupou um importante papel nos debates e nas lutas da esquerda nas décadas de 1960 e 1970. Apesar da sua influência na direção e formulação das linhas políticas da POLOP, Érico Sachs permanece quase desconhecido de militantes e historiadores. Usando o conceito de 'atualidade da revolução' de Lukacs, pretende-se entender a influência causada pela estratégia defendida por Sachs, especialmente nos anos 1960, e o seu isolamento, nos anos 1970 e 1980, assim como o seu posterior 'esquecimento'.

We firstly numerically recalculate the Ricci tensor of non-stationary axisymmetric space-times (originally calculated by Chandrasekhar) and we find some discrepancies both in the linear and non-linear terms. However, these discrepancies do not affect the results concerning linear perturbations of a Schwarzschild black hole. Secondly, we use these Ricci tensors to derive the Zerilli and Regge-Wheeler equations and use the Newman-Penrose formalism to derive the Bardeen-Press equation. We show the relation between these equations because they describe the same linear perturbations of a Schwarzschild black hole. Thirdly, we illustrate heuristically (when the angular momentum (l) is 2) the relation between the linearized solution of the Einstein vacuum equations obtained from the Bondi-Sachs metric and the Zerilli equation, because they describe the same linear perturbations of a Schwarzschild black hole. Lastly, by means of a coordinate transformation, we extend Chandrasekhar's results on linear perturbations of a Schwarzschild black hole to the Bondi-Sachs framework. / Mathematical Sciences / M. Sc. (Applied Mathematics)

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When calculating scattering amplitudes in gauge and gravitational theories one encounters infrared (IR) divergences associated with massless fields. These are known to be artifacts of constructing a quantum field theory starting with free fields, and the assumption that in the asymptotic limit (i.e. well before and after a scattering event) the incoming and outgoing states are non-interacting. In 1937, Bloch and Nordsieck provided a technical procedure eliminating the IR divergences in the cross-sections. However, this did not address the source of the problem: A detailed analysis reveals that, in quantum electrodynamics (QED) and in perturbative quantum gravity (PQG), the interactions cannot be ignored even in the asymptotic limit. This is due to the infinite range of the massless force-carrying bosons. By taking these asymptotic interactions into account, one can find a picture changing operator that transforms the free Fock states into asymptotically interacting Faddeev- Kulish (FK) states. These FK states are charged (massive) particles surrounded by a “cloud” of soft photons (gravitons) and will render all scattering processes infrared finite already at an S-matrix level. Recently it has been found that the FK states are closely related to asymptotic symmetries. In the case of QED the FK states are eigenstates of the large gauge transformations – U(1) transformations with a non-vanishing transformation parameter at infinity. For PQG the FK states are eigenstates of the Bondi-Metzner-Sachs (BMS) transformations – the asymptotic symmetry group of an asymptotically flat spacetime. It also appears that the FK states are related the Wilson lines in the Mandelstam quantization scheme. This would allow one to obtain the physical FK states through geometrical or symmetry arguments. We attempt to clarify this relation and present a derivation of the FK states in PQG from the gravitational Wilson line in the eikonal approximation, a result that is novel to this thesis.

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No description available.

This thesis concerns the mathematical modelling of phase transformations with a special emphasis on martensitic phase transformations and their application to the modelling of steels. In Chapter 1, we develop a framework that determines the optimal transformation strain between any two Bravais lattices and use it to give a rigorous proof of a conjecture by E.C. Bain in 1924 on the optimality of the so-called Bain strain. In Chapter 2, we review the Ball-James model and related concepts. We present some simplification of existing results. In Chapter 3, we pose a conjecture for the explicit form of the quasiconvex hull of the three tetragonal wells, known as the three-well problem. We present a new approach to finding inner and outer bounds. In Chapter 4, we focus on highly compatible, so called self-accommodating, martensitic structures and present new results on their fine properties such as estimates on their minimum complexity and bounds on the relative proportion of each martensitic variant in them. In Chapter 5, we investigate the contrary situation when self-accommodating microstructures do not exist. We determine, whether in this situation, it is still energetically favourable to nucleate martensite within austenite. By constructing different types of inclusions, we find that the optimal shape of an inclusion is flat and thin which is in agreement with experimental observation. In Chapter 6, we introduce a mechanism that identifies transformation strains with orientation relationships. This mechanism allows us to develop a simpler, strain-based approach to phase transformation models in steels. One novelty of this approach is the derivation of an explicit dependence of the orientation relationships on the ratio of tetragonality of the product phase. In Chapter 7, we establish a correspondence between common phenomenological models for steels and the Ball-James model. This correspondence is then used to develop a new theory for the (5 5 7) lath transformation in low-carbon steels. Compared to existing theories, this new approach requires a significantly smaller number of input parameters. Furthermore, it predicts a microstructure morphology which differs from what is conventionally believed.

This study has collected and analysed a database of place-names containing potential ethnonymic elements. Competing models of ethnicity are investigated and applied to names about which there is reasonable confidence. A number of motivations for employment of ethnonyms in place-names emerge. Ongoing interaction between ethnicities is marked by reference to domain or borderland, and occasional interaction by reference to resource or transit. More superficial interaction is expressed in names of commemorative, antiquarian or figurative motivation. The implications of the names for our understanding of the history of individual ethnicities are considered. Distribution of Walh-names has been extended north into Scotland; but reference may be to Romance-speaking feudal incomers, not the British. Briton-names are confirmed in Cumberland and are found on and beyond the fringes of the polity of Strathclyde. Dumbarton, however, is an antiquarian coining. Distribution of Cumbrian-names suggests that the south side of the Solway Firth was not securely under Cumbrian influence; but also that the ethnicity, expanding in the tenth century, was found from the Ayrshire coast to East Lothian, with the Saxon culture under pressure in the Southern Uplands. An ethnonym borrowed from British in the name Cumberland and the Lothian outlier of Cummercolstoun had either entered northern English dialect or was being employed by the Cumbrians themselves to coin these names in Old English. If the latter, such self-referential pronouncement in a language contact situation was from a position of status, in contrast to the ethnicism of the Gaels. Growing Gaelic self-awareness is manifested in early-modern domain demarcation and self-referential naming of routes across the cultural boundary. But by the nineteenth century cultural change came from within, with the impact felt most acutely in west-mainland and Hebridean Argyll, according to the toponymic evidence. Earlier interfaces between Gaelic and Scots are indicated on the east of the Firth of Clyde by the early fourteenth century, under the Sidlaws and in Buchan by the fifteenth, in Caithness and in Perthshire by the sixteenth. Earlier, Norse-speakers may have referred to Gaels in the hills of Kintyre. The border between Scotland and England was toponymically marked, but not until the modern era. In Carrick, Argyll and north and west of the Great Glen, Albanians were to be contrasted, not necessarily linguistically, from neighbouring Gaelic-speakers; Alba is probably to be equated with the ancient territory of Scotia. Early Scot-names, recorded from the twelfth century, similarly reflect expanding Scotian influence in Cumberland and Lothian. However, late instances refer to Gaelic-speakers. Most Eireannach-names refer to wedder goats rather than the ethnonym, but residual Gaelic-speakers in east Dumfriesshire are indicated by Erisch­-names at the end of the fifteenth century or later. Others west into Galloway suggest an earlier Irish immigration, probably as a consequence of normanisation and of engagement in Irish Sea politics. Other immigrants include French estate administrators, Flemish wool producers and English feudal subjects. The latter have long been discussed, but the relationship of the north-eastern Ingliston-names to mottes is rejected, and that of the south-western Ingleston-names is rather to former motte-hills with degraded fortifications. Most Dane-names are also antiquarian, attracted less by folk memory than by modern folklore. The Goill could also be summoned out of the past to explain defensive remains in particular. Antiquarianism in the eighteenth century onwards similarly ascribed many remains to the Picts and the Cruithnians, though in Shetland a long-standing supernatural association with the Picts may have been maintained. Ethnicities were invoked to personify past cultures, but ethnonyms also commemorate actual events, typified by Sasannach-names. These tend to recall dramatic, generally fatal, incidents, usually involving soldiers or sailors. Any figures of secular authority or hostile activity from outwith the community came to be considered Goill, but also agents of ecclesiastical authority or economic activity and passing travellers by land or sea. The label Goill, ostensibly providing 178 of the 652 probable ethnonymic database entries, is in most names no indication of ethnicity, culture or language. It had a medieval geographical reference, however, to Hebrideans, and did develop renewed, early-modern specificity in response to a vague concept of Scottish society outwith the Gaelic cultural domain. The study concludes by considering the forms of interaction between ethnicities and looking at the names as a set. It proposes classification of those recalled in the names as overlord, interloper or native.