Integrins are major adhesion receptors for the extracellular matrix (ECM). This thesis focuses on the motifs and interactions within integrin cytoplasmic tails during integrin-mediated cell adhesion and spreading. The present study investigated the significance of the skelemin-αIIbβ3 interaction using Chinese Hamster Ovary (CHO) cells expressing wild-type or mutant αIIbβ3 receptors defective in skelemin binding. Most mutant cells displayed unimpaired adhesive capacity and spreading on immobilized fibrinogen at the early stages of cell spreading. In addition, they formed normal focal adhesions and stress fibers with no indication of impaired cell spreading. K716A and H722A mutant cells exhibited the greatest cell spreading, which was associated with enhanced p-Src activation. The K716 residue appeared to be the most important for skelemin binding in previous in vitro studies. Here, the protrusions of the leading edge of K716A cells showed strong colocalization of talin with αIIbβ3 which was associated with a loss in skelemin binding. These data suggest that the binding of skelemin to αIIbβ3 is not essential for normal cell spreading, but may act to exert contractile forces on cell spreading and coordinate the binding of talin to the membrane proximal region of integrin tails. The functional mode of peptides corresponding to the central motifs of the αIIb and αV tail, KRNRPPLEED (αIIb peptide) and KRVRPPQEEQ (αV peptide) was also investigated. Both peptides inhibited Mn2+-activated αIIbβ3 binding to soluble fibrinogen as well as the binding of αIIbβ3-expressing CHO cells to immobilized fibrinogen. Breast cancer progression has been linked to tumor cell interaction with ECM. Our αIIb and αV peptides also inhibited adhesion of two breast cancer cell lines (MDA-MB-435 and MCF7) to αV integrin ECM ligand vitronectin. Replacement of RPP with AAA significantly attenuated the inhibitory activity of the αIIb peptide. β-tubulin was identified as a potential αIIb peptide-binding partner, suggesting that microtubule cytoskeleton may participate in the regulation of integrin functions. These results provide insights into the mechanisms by which the central motifs of αIIb and αV tails regulate integrin activation and integrin-mediated cell adhesion

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One of the most challenging topics in financial time series analysis is the modeling of conditional variances of asset returns. Although conditional variances are not directly observable there are numerous approaches in the literature to overcome this problem and to predict volatilities on the basis of historical asset returns. The most prominent approach is the class of GARCH models where conditional variances are governed by a linear autoregressive process of past squared returns and variances. Recent research in this field, however, has focused on modeling asymmetries of conditional variances by means of non-linear models. While there is evidence that such an approach improves the fit to empirical asset returns, most non-linear specifications assume conditional normal distributions and ignore the importance of alternative models. Concentrating on the distributional assumptions is, however, essential since asset returns are characterized by excess kurtosis and hence fat tails that cannot be explained by models with suffcient heteroskedasticity. In this paper we take up the issue of returns' distributions and contrast it with the specification of non-linear GARCH models. We use daily returns for the Dow Jones Industrial Average over a large period of time and evaluate the predictive power of different linear and non-linear volatility specifications under alternative distributional assumptions. Our empirical analysis suggests that while non-linearities do play a role in explaining the dynamics of conditional variances, the predictive power of the models does also depend on the distributional assumptions. (author's abstract) / Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

For the purpose of modelling and prediction of volatility, the family of Stochastic Volatility (SV) models is an alternative to the extensively used ARCH type models. SV models differ in their assumption that volatility itself follows a latent stochastic process. This reformulation of the volatility process makes however model estimation distinctly more complicated for the SV type models, which in this paper is conducted through Markov Chain Monte Carlo methods. The aim of this paper is to assess the standard SV model and the SV model assuming t-distributed errors and compare the results with their corresponding GARCH(1,1) counterpart. The data examined cover daily closing prices of the Swedish stock index OMXS30 for the period 2010-01-05 to 2016- 03-02. The evaluation show that both SV models outperform the two GARCH(1,1) models, where the SV model with assumed t-distributed error distribution give the smallest forecast errors.

Despite its recent advent, value at risk (VaR) became the most widely used technique for measuring future expected risk for both financial and non-financial institutions. VaR, the measure of the worst expected loss over a given horizon at a given confidence level, depends crucially on the distributional aspects of trading revenues. Existing VaR models do not capture adequately some empirical aspects of financial data such as the tail thickness, which is vital in VaR calculations. Tail thickness in financial variables results basically from stochastic volatility and event risk (jumps). Those two sources are not totally separated; under event risk, volatility updates faster than under normal market conditions. Generally, tail thickness is associated with hyper volatility updating. Existing VaR literature accounts partially for tail thickness either by including stochastic volatility or by including jump diffusion, but not both. Additionally, this literature does not account for fast updating of volatility associated with tail thickness. This dissertation fills the gap by developing analytical VaR models account for the total (maximum) tail thickness and the associated fast volatility updating. Those aspects are achieved by assuming that trading revenues are evolving according to a mixed non-affine stochastic volatility-jump diffusion process. The mixture of stochastic volatility and jumps diffusion accounts for the maximum tail thickness, whereas the nonaffine structure of stochastic volatility captures the fast volatility updating. The non-affine structure assumes that volatility dynamics are non-linearly related to the square root of current volatility rather than the traditional linear (affine) relationship. VaR estimates are obtained by deriving the conditional characteristic function, and then inverting it numerically via the Fourier Inversion technique to infer the cumulative distribution function. The application of the developed VaR models on a sample that contains six U.S banks during the period 1995-2002 shows that VaR models based on the non-affine stochastic volatility and jump diffusion process produce more reliable VaR estimates compared with the banks' own VaR models. The developed VaR models could significantly predict the losses that those banks incurred during the Russian crisis and the near collapse of the LTCM in 1998 when the banks' VaR models fail.

El presente trabajo de investigación busca identificar y analizar los principales problemas relacionados a la exportación de cola de langostino de acuicultura con destino a EEUU durante los años 2013-2018; se trabajó una investigación cualitativa longitudinal, utilizando herramientas como el análisis de documentos y entrevistas a profundidad semi estructuradas. La estructura establecida para el presente trabajo fue en primer lugar, el análisis del marco teórico, donde se buscó estudios pasados que sustenten y acrediten nuestro problema de investigación; en segundo lugar, se realizó un análisis documental; para ello se emplearon fuentes como SUNAT, VERITRADE y TRADEMAP, que proporcionan información real de toda la actividad económica del país ya sea importación o exportación del producto a investigar; y por último, en tercer lugar, fue la realización de entrevistas a profundidad; las mismas que fueron realizadas a profesionales del rubro que tienen en promedio 10 años de experiencia y laboran en las principales empresas del sector. Se tomó una muestra de un total de 14 entrevistas semiestructuradas, dado a que se llegó al punto de saturación. Finalmente, se realizó un análisis en triangulación, ya que se contrastó lo expresado en el marco teórico, con lo hallado en los documentos, y el resultado de las entrevistas; obteniendo nuevas categorías, que servirán como base para otros investigadores que desarrollen un tema relacionado. / This research seeks to identify and analyze the main problems related to the export of shrimp tail of aquaculture to the US during the years 2013-2018; a longitudinal qualitative research was carried out, using tools such as document analysis and semi-structured in-depth interviews. The structure established for the present work was, first of all, the analysis of the theoretical framework, where past studies were sought to sustain and accredit our research problem; Secondly, a documentary analysis was carried out; For this, sources such as SUNAT, VERITRADE and TRADEMAP were used, which provide real information on all the economic activity of the country, whether it is import or export of the product to be investigated; and finally, it was conducting in-depth interviews; the same ones that were carried out to professionals of the sector that have on average 10 years of experience and work in the main companies of the sector. A sample of a total of 14 semi-structured interviews was taken, given that the point of saturation was reached. Finally, an analysis was carried out in triangulation, since what was expressed in the theoretical framework was contrasted with what was found in the documents and the results of the interviews; obtaining new categories, which will serve as a basis for other researchers to develop a related topic. / Tesis

All living hominoids are characterized by taillessness and adaptations to orthograde (upright) trunk posture. Accordingly, these features have importance for our understanding of ape origins, evolutionary relationships and positional behaviors. Despite extensive study of the hominoid postcranial skeleton, researchers continue to face difficulty identifying taillessness and orthogrady from fossil material. In part, difficulties persist because although the Miocene fossil record indicates that the evolution of tail loss and orthogrady was decoupled, previous research has focused primarily on how the skeletal anatomy of extinct apes resembles that of living apes, in which these traits appear in conjunction. The remarkable diversity in tail lengths and positional behaviors exhibited by other mammals presents a valuable opportunity to employ the strength of the comparative method for testing functional hypotheses. The goal of this dissertation is to identify anatomical correlates of tail length and positional behaviors from sacral and caudal vertebral morphology among primates and other mammals in three studies. The first study examines the relationship between trabecular structure in the first sacral vertebra and positional behaviors (N= 78 primates). The second study quantifies aspects of internal (N=78 primates) and external (N= 472 mammals) sacral anatomy for correlates of relative tail length. The third study evaluates the functional morphology of caudal vertebrae among nonprehensile-tailed primates and other mammals that vary in relative tail length, offering additional insight into the anatomy associated with tail loss (N=333). The relationship between trabecular structure in the proximal sacrum and positional behaviors among living primates is somewhat unclear. Some trabecular parameters in the distal sacrum appear to have a relationship with tail length. Results support the functional links between previously and newly defined metrics from the external morphology of sacra and caudal vertebrae, and relative tail length, among primates and other mammals. Identified anatomical correlates from the extant primate sample are used to reconstruct the tail lengths of extinct primates. From the sacral data, Proconsul is reconstructed as tailless, Archaeolemur likely possessed a long tail, and Palaeopropithecus, Megaladapis and Epipliopithecus had short tails. From the caudal vertebrae data, Archaeolemur is reconstructed as possessing a long tail and Palaeopropithecus is reconstructed as having a short tail. / text

For the first time the interfacial properties of nonionic hydrocarbon surfactants at both the air-water and CO₂-water interfaces are investigated in terms of surfactant structure to determine the changes in surfactant efficiency (negative of the logarithm of the surfactant concentration to create a surface pressure of 20 mN/m). At the air-water interface, linear surfactant tails are more efficient due to the higher packing ability of the straight chains in the dense surfactant monolayer. However, at the CO₂-water interface, surfactant adsorption is small and tails can be solvated. Thus, branching which increases both tail solvation and tail hydrophobicity also enlarges the hard disk area of the surfactant to ultimately increase the efficiency of the surfactant at the CO₂-water interface. CO₂-in-water concentrated emulsions (foams) are studied over short and long times to evaluate the foam stability as a function of both surfactant structure and foam conditions using in-situ optical microscopy. The surface pressure measured at the CO₂- water interface is correlated with the short time stability of coalescing foams with very small cell sizes (under 0.4 [mu]m in diameter). Long time stability of bubbles to coalescence is shown under a variety of conditions. The rheology of these bulk CO₂-in-water foams under high-pressure conditions are also evaluated through measurements of the pressure drop over a capillary tube. Viscosities in excess of 200 cP are measured, an increase of over 1000 time that of pure CO₂ (0.09 cP at 24 °C and 2000 psia). The viscosity of the C/W foams are found to correlate with bubble size, continuous phase viscosity, shear rate, and interfacial tension. Hydrophobic silica particles adsorbed at the interface are also used to stabilize water-in-CO₂ emulsions as an alternative to surfactant stabilizers. The difficulties of tail solvation associated with many hydrocarbon surfactants in CO₂ can be removed by using particles instead of surfactant. A porous cross-linked shell is formed about the hydrophilic (colloidal and fumed) silica to render the particles CO₂-philic and the crosslinking removes ligand tails from the particle surface. / text

Orientador: Carmen Zink Bolonhini / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem / Made available in DSpace on 2018-08-14T10:21:25Z (GMT). No. of bitstreams: 1 Goldstein_MariaSuelyOliveira_D.pdf: 7907811 bytes, checksum: 726cb0d6333465b9ac30ca46be8cc127 (MD5) Previous issue date: 2009 / Resumo: Esta Tese se respalda nas seguintes premissas: a) estudos que evidenciem questões culturais e enunciativas devem ocupar um lugar constitutivo no ensino-aprendizagem de língua; b) consideramos que um lugar de destaque para a inserção desses componentes é no currículo de línguas. Uma das vias que propomos, para que esse objetivo seja alcançado, é que se leve em consideração a memória discursiva, que é dada, por exemplo, pela junção entre a literatura e o ensino de língua. No nosso caso, as compilações de contos populares se mostraram muito apropriadas para tal fim, pelo fato de elas registrarem parte da memória e da história dos povos. Essa reivindicação se respalda no postulado de que a "enunciação em outras línguas, ou em variantes diversas da própria língua materna, é uma experiência que mobiliza questões de identidade, e paulatinamente culturais, sejam elas implícitas ou explícitas, presentes em toda aula de língua" (Revuz, 1998). Naquele ambiente, o professor deve, de acordo com o quadro teórico aqui adotado, estar atento aos conflitos de identidade e sociais que se apresentam nas práticas da língua em sala de aula, que são determinados pela própria língua, que materializa a cultura dos sujeitos. Esse professor, observador da discursividade, deve estar alerta para as diferenças enunciativas, no que tange, por exemplo, às inter-relações que ali acontecem. Tal providência visa, entre outras coisas, propiciar, por exemplo, a diluição de mal-entendidos interculturais, provocados pelas diferenças de formação discursiva dos sujeitos. Para contemplar essa proposta, investigamos os currículos bilíngües de dois colégios alemães particulares, situados no Estado de São Paulo. A pesquisa que nesses ambientes é empreendida trata, em grandes linhas, por um lado, do tratamento dado aos domínios sociocultural e literário, nos currículos da educação bilíngüe desses colégios, e, por outro, das compilações em foco e do discurso de professor e alunos - investigando o debate oral, desencadeado pela leitura de contos populares, na construção de práticas letradas orais, em aulas de línguas, do nível II, do Ensino Fundamental, de uma dessas escolas bilíngües. Além disso, também examinamos questões sobre as relações socioculturais do sujeito, aqui especificamente com o meio ambiente, que aparecem nas aulas e nos contos populares pesquisados, observando, além de repetições discursivas (Pêcheux, 1983) sobre esse tema naqueles ambientes e de outros aspectos discursivos que se mostram ali relevantes, a diluição de mal-entendidos interculturais em práticas letradas, mediadas pelo professor e a mobilização de questões de identidade e culturais que ali acontecem. / Abstract: This work is based on the following premises: a) studies that focus on cultural and enunciation issues must have a constitutive place in the teaching-learning of languages; b) we consider the language curriculum to be a central and significant place for the insertion of such components. One of the paths proposed to achieve this objective is to take into consideration the discursive memory, brought about, for instance, by the combination of literature and the teaching of languages. In our case, compilations of popular tales have proven to be very appropriate to this end, as they register part of the memory and history of the people. This affirmation is founded in the assertion that enunciation in other languages, or the many variants of the mother tongue, is an experience that mobilizes issues of identity and culture, either implicit or explicit, throughout the language class (Revuz, 1998). According to the theoretical framework adopted in this study, in that situation, the teacher must be aware of the identity and social conflicts present in the practice of language within the class, determined by the language itself, which materializes the culture of the subjects involved. Such a teacher, observant of discursiveness, must be aware of enunciation differences in relation, for example, to the inter-relations that occur in those circumstances. Among other things, this action aims at promoting, for instance, the clarification of intercultural misunderstandings, resulting from the different discursive background of the subjects. In order to contemplate this proposal, we investigated the curricula of two bilingual (German/Portuguese) private schools in the state of São Paulo. In broad terms, the study conducted in such settings includes, on one hand, the treatment given to the sociocultural and literary domains, in the bilingual education curricula of those schools, and, on the other hand, the compilations mentioned as well as the discourse of both teacher and students, thus investigating oral debates, resultant from the reading of popular tales, in the construction of oral literacy practices, in the language classes of Level II, in Elementary School, in one of the bilingual schools mentioned. In addition to that, issues related to the sociocultural relationships of the subjects, in this case specifically with the environment, which appear in the classes and in the popular tales studied were also examined. Discursive repetitions (Pêcheux, 1983) about the theme in those contexts, as well as other discursive aspects that seemed relevant, the dissolution of intercultural misunderstandings in literacy practices mediated by the teacher, and the mobilization of identity and cultural issues present in the situation were also observed. / Doutorado / Multiculturalismo, Plurilinguismo e Educação Bilingue / Doutor em Linguística Aplicada

The Wide-field Infrared Survey Explorer (WISE) mission surveyed the sky in four infrared wavelength bands (3.4, 4.6, 12 and 22 μm) between January 2010 and February 2011. During the mission, WISE serendipitously observed 160 comets, including 21 newly discovered objects. About 89 of the comets observed by WISE displayed a significant dust tail in the 12 and 22 μm (thermal emission) bands, showing a wide range of activity levels and dust morphology. Since the observed objects are a mix of both long-period comets (LPCs) and short-period comets (SPCs), differences in their activity can be used to better understand the thermal evolution that each of these populations has undergone. For the comets that displayed a significant dust tail, we have estimated the sizes and ages of the particles using dynamical models based on the Finson-Probstein method [Finson and Probstein, 1968]. For a selection of 40 comets, we have then compared these models to the data using a novel tail-fitting method that allows the best-fit model to be chosen analytically rather than subjectively. For comets that were observed multiple times by WISE, the particle properties were estimated separately, and then compared. We find that the dust tails of both LPCs and SPCs are primarily comprised of ~mm-cm sized particles, which were the result of emission that occurred several months to several years prior to the observations. The LPCs nearly all have strong emission close to the comet*s perihelion distance, and the SPCs mostly have strong emission close to perihelion, but some have strong emission well before perihelion.