Terrestrial magma ocean solidification and formation of a candidate D" layer

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 31-34).In this thesis we investigate the solidification of early magma oceans on the Earth and the formation of a deep dense layer at the core-mantle boundary. We also study the concentrations and densities of the last layers of the solidified magma ocean and how they create a deep dense layer after solid-state overturn. The deep dense layer that forms in our model matches the bulk physical properties of the D" layer observed by other workers. This layer is also sufficiently dense that the bulk of its material is not reentrained by the mantle after the onset of convection, and that this layer is enriched in incompatible elements such as samarium and neodymium regardless of distribution coefficients used for incompatible elements in mantle minerals such as perovskite. However, we found that this probable D" layer is more enriched in samarium than is to be expected for a planet's mantle which evolves from an initially chondritic composition.by Alessondra Springmann.S.M

Transfer Learning for OCRopus Model Training on Early Printed Books

A method is presented that significantly reduces the character error rates for OCR text obtained from OCRopus models trained on early printed books when only small amounts of diplomatic transcriptions are available. This is achieved by building from already existing models during training instead of starting from scratch. To overcome the discrepancies between the set of characters of the pretrained model and the additional ground truth the OCRopus code is adapted to allow for alphabet expansion or reduction. The character set is now capable of flexibly adding and deleting characters from the pretrained alphabet when an existing model is loaded. For our experiments we use a self-trained mixed model on early Latin prints and the two standard OCRopus models on modern English and German Fraktur texts. The evaluation on seven early printed books showed that training from the Latin mixed model reduces the average amount of errors by 43% and 26%, respectively compared to training from scratch with 60 and 150 lines of ground truth, respectively. Furthermore, it is shown that even building from mixed models trained on data unrelated to the newly added training and test data can lead to significantly improved recognition results

Small is Successful!?

This paper provides experimental evidence on exit behavior of asymmetrically sized firms in a duopoly with declining demand. We conduct three treatments: (a) The basic model with indivisible real capital. The structure of this treatment represents the main findings of Ghemawat and Nalebuff (1985); (b) an extension of the basic model by introducing a bankruptcy constraint; (c) here we allow for divisible real capital (Ghemawat and Nalebuff (1990)). In all three treatments we find behavior that is, by and large, in line with subgame perfect Nash Equilibrium. However, there is a problem of multiplicity of equilibria in (b) and we find an anchor effect as well as learning effects in (c).Exit, duopoly, declining market, experimental economics

Profiling of OCR'ed Historical Texts Revisited

In the absence of ground truth it is not possible to automatically determine the exact spectrum and occurrences of OCR errors in an OCR'ed text. Yet, for interactive postcorrection of OCR'ed historical printings it is extremely useful to have a statistical profile available that provides an estimate of error classes with associated frequencies, and that points to conjectured errors and suspicious tokens. The method introduced in Reffle (2013) computes such a profile, combining lexica, pattern sets and advanced matching techniques in a specialized Expectation Maximization (EM) procedure. Here we improve this method in three respects: First, the method in Reffle (2013) is not adaptive: user feedback obtained by actual postcorrection steps cannot be used to compute refined profiles. We introduce a variant of the method that is open for adaptivity, taking correction steps of the user into account. This leads to higher precision with respect to recognition of erroneous OCR tokens. Second, during postcorrection often new historical patterns are found. We show that adding new historical patterns to the linguistic background resources leads to a second kind of improvement, enabling even higher precision by telling historical spellings apart from OCR errors. Third, the method in Reffle (2013) does not make any active use of tokens that cannot be interpreted in the underlying channel model. We show that adding these uninterpretable tokens to the set of conjectured errors leads to a significant improvement of the recall for error detection, at the same time improving precision

The optimization air separation plants for combined cycle MHD-power plant applications

Some of the design approaches being employed during a current supported study directed at developing an improved air separation process for the production of oxygen enriched air for magnetohydrodynamics (MHD) combustion are outlined. The ultimate objective is to arrive at conceptual designs of air separation plants, optimized for minimum specific power consumption and capital investment costs, for integration with MHD combined cycle power plants

Alteração de cor da coroa dental após a terapia endodôntica regenerativa: Revisão de literatura

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Odontologia.O objetivo deste estudo foi revisar, de modo sistematizado e por meio de casos clínicos, o efeito de materiais usados na terapia endodôntica regenerativa sobre a cor da coroa dental, bem como estudar os procedimentos para evitar ou reverter eventuais alterações de cor e os métodos utilizados para a determinação da cor. Para localização dos estudos, foi desenvolvida uma detalhada estratégia de busca para cada uma das seguintes bases de dados: Pubmed, Scopus e Web of Science. Foram utilizados termos de busca relacionados ao tema, tais como: alteração da cor dental, coloração, descoloração dental, estética, dente não vital, desvitalização pulpar, necrose pulpar, polpa dental, procedimento endodôntico regenerativo, regeneração, revitalização, revascularização, tratamento endodôntico regenerativo. As referências encontradas foram gerenciadas via software EndNoteTM Basic. Foram incluídos apenas estudos clínicos relacionados à cor da coroa de dentes humanos avaliados antes e após procedimentos endodônticos regenerativos. Cartas, capítulos de livros, resumos de conferências (anais) e revisões foram excluídos. Após a seleção por título/resumo, os artigos foram incluídos para leitura do texto completo, dos quais dados referentes à metodologia e aos resultados foram extraídos e sequencialmente analisados. Concluiu-se que a pasta triantibiótica, que contém minociclina, está mais relacionada à alteração de cor do que as demais medicações intracanal, e que a descoloração ocorreu independentemente do tipo de material utilizado no plug cervical, MTA branco ou MTA cinza. Nenhum método para prevenir ou reverter eventuais alterações de cor foi totalmente efetivo. O método mais utilizado para determinar a cor foi o visual