531 resultados para Discontinuity


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En el presente trabajo intentaremos analizar cierta serie o tradición de reflexiones sobre el conocimiento científico que lo caracterizan por su discontinuidad en relación al conocimiento ordinario o sentido común. El origen de esta serie puede localizarse en la obra de Gaston Bachelard y su peculiar estudio de los actos epistemológicos con los que se rompe con el pasado en una disciplina científica. Estos actos contrastan con lo que este autor califica como el "mito continuista" del empirismo. Esta posición será apropiada por Althusser y desarrollada por sus discípulos Balibar y Pêcheux. Intentaremos mostrar que el factor común de la discontinuidad no constituye ;una posición monolítica, sino que cabe reconocer, en las posiciones que consideramos, maneras diversas de entender la naturaleza de la misma. En este sentido, la revisión de las posiciones que Althusser efectuó en su "autocrítica" constituye un punto de observación privilegiado del abanico de alternativas que algunos de sus discípulos desarrollarían sobre bases diversas

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En el presente trabajo intentaremos analizar cierta serie o tradición de reflexiones sobre el conocimiento científico que lo caracterizan por su discontinuidad en relación al conocimiento ordinario o sentido común. El origen de esta serie puede localizarse en la obra de Gaston Bachelard y su peculiar estudio de los actos epistemológicos con los que se rompe con el pasado en una disciplina científica. Estos actos contrastan con lo que este autor califica como el "mito continuista" del empirismo. Esta posición será apropiada por Althusser y desarrollada por sus discípulos Balibar y Pêcheux. Intentaremos mostrar que el factor común de la discontinuidad no constituye ;una posición monolítica, sino que cabe reconocer, en las posiciones que consideramos, maneras diversas de entender la naturaleza de la misma. En este sentido, la revisión de las posiciones que Althusser efectuó en su "autocrítica" constituye un punto de observación privilegiado del abanico de alternativas que algunos de sus discípulos desarrollarían sobre bases diversas

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Short-term spectral analysis was carried out on geochemical logging data from ODP Site 704. The FFT was used to compute the amplitude spectra of short-term overlapping segments to produce depth-period-amplitude spectrograms of the logging data. The spectrograms provided a means of evaluating the significance of the observed periodic components. The periodic components that were consistently present and prominent across a given record interval were considered to be significant. Changes in the spectrogram characteristics seem to reflect changes in either lithology, sedimentation rates, or hiatuses and may therefore provide useful information to aid in stratigraphic and paleoenvironmental studies. The dominant periodicity during the late Pleistocene and Brunhes Chron (0.97 to 0.47 Ma) was determined to be > 100,000 yr whereas the upper Matuyama Chron was dominated by the 41,000-yr periodicity. These periodicities suggest that the sedimentation patterns within the upper Matuyama Chron (0.98-1.78 Ma) were influenced by the Milankovitch obliquity cycle and those within the latest Matuyama-Brunhes Chron (<0.98 Ma) by the eccentricity cycle. The Brunhes/Matuyama boundary therefore represents a major discontinuity. Periodicities observed within the lower Matuyama and the upper Gauss Chron did not correlate with any of the periodicities within the Milankovitch frequency bands.

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Conventional K-Ar ages have been determined and inert-gas abundances have been measured on representative samples of altered rocks from Deep Sea Drilling Project Holes 501, 504B, and 505B in an attempt to correlate their degree of alteration with inert-gas and K-Ar data. Samples taken from the first 60 meters below the sediment/basalt interface give significantly higher ages than would be expected from the magnetic stratigraphy, though at greater depths the calculated ages are in broad agreement with the expected age. The inert gas ratios 20Ne/36Ar, 36Ar/84Kr, and 84Kr/130Xe also show a marked discontinuity at the 60-meter depth, and all these effects are interpreted as being a consequence of low-temperature alteration produced by burial metamorphism and by interaction with sea water (halmyrolysis).

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En el presente trabajo intentaremos analizar cierta serie o tradición de reflexiones sobre el conocimiento científico que lo caracterizan por su discontinuidad en relación al conocimiento ordinario o sentido común. El origen de esta serie puede localizarse en la obra de Gaston Bachelard y su peculiar estudio de los actos epistemológicos con los que se rompe con el pasado en una disciplina científica. Estos actos contrastan con lo que este autor califica como el "mito continuista" del empirismo. Esta posición será apropiada por Althusser y desarrollada por sus discípulos Balibar y Pêcheux. Intentaremos mostrar que el factor común de la discontinuidad no constituye ;una posición monolítica, sino que cabe reconocer, en las posiciones que consideramos, maneras diversas de entender la naturaleza de la misma. En este sentido, la revisión de las posiciones que Althusser efectuó en su "autocrítica" constituye un punto de observación privilegiado del abanico de alternativas que algunos de sus discípulos desarrollarían sobre bases diversas

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Studying landscape evolution of the Earthís surface is difficult because both tectonic forces and surface processes control its response to perturbation, and ultimately, its shape and form. Researchers often use numerical models to study erosional response to deformation because there are rarely natural settings in which we can evaluate both tectonic activity and topographic response over appropriate time scales (103-105 years). In certain locations, however, geologic conditions afford the unique opportunity to study the relationship between tectonics and topography. One such location is along the Dragonís Back Pressure Ridge in California, where the landscape moves over a structural discontinuity along the San Andreas Fault and landscape response to both the initiation and cessation of uplift can be observed. In their landmark study, Hilley and Arrowsmith (2008) found that geomorphic metrics such as channel steepness tracked uplift and that hillslope response lagged behind that of rivers. Ideal conditions such as uniform vegetation density and similar lithology allowed them to view each basin as a developmental stage of response to uplift only. Although this work represents a significant step forward in understanding landscape response to deformation, it remains unclear how these results translate to more geologically complex settings. In this study, I apply similar methodology to a left bend along the San Andreas Fault in the Santa Cruz Mountains, California. At this location, the landscape is translated through a zone of localized uplift caused by the bend, but vegetation, lithology, and structure vary. I examine the geomorphic response to uplift along the San Andreas Fault bend in order to determine whether predicted landscape patterns can be observed in a larger, more geologically complex setting than the Dragonís Back Pressure Ridge. I find that even with a larger-scale and a more complex setting, geomorphic metrics such as channel steepness index remain useful tools for evaluating landscape evolution through time. Steepness indices in selected streams of study record localized uplift caused by the restraining bend, while hillslope adjustment in the form of landsliding occurs over longer time scales. This project illustrates that it is possible to apply concepts of landscape evolution models to complex settings and is an important contribution to the body of geomorphological study.

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Thesis (Master's)--University of Washington, 2016-06

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Background: It is generally assumed that fascial defects in the rectovaginal septum are the result of childbirth. However, rectoceles do occur in women who have never delivered vaginally. Aims: To determine the incidence of rectocele in a cohort of asymptomatic, young nulliparous women. Methods: Observational cohort study on 178 nulliparous caucasian women (aged 18-24) recruited for a twin study of pelvic floor dysfunction. All women were interviewed and examined by translabial ultrasound, supine and after voiding. In 52 women, 3D imaging was obtained and 171 datasets were complete and available for analysis. Ultrasound findings were reviewed for rectovaginal septal integrity by an assessor blinded against interview and demographic data for rectovaginal septal integrity. Results: A discontinuity of the anterior rectal wall with extrusion of rectal mucosa or contents (depth of ! 10 mm) was observed in 21/171 (12%). The depth of this herniation ranged from 10 to 25 mm and was filled with stool (n = 10) or rectal mucosa (n = 11). Defects were associated with a higher BMI (P = 0.049), with the complaint of constipation (P = 0.049) and non-significantly with straining at stool (P = 0.09). Descent of the ampulla to beyond the level of the symphysis pubis without fascial defect, that is, significant perineal relaxation, was observed in 23/171 (13%). Conclusions: Twelve percent of 171 young nulligravid caucasian women showed a defect of the rectovaginal septum. Associations were observed with higher body mass index and a history of constipation. It is hypothesised that in some women defects of the rectovaginal septum and perineal hypermobility may be congenital in nature.

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Short proteins play key roles in cell signalling and other processes, but their abundance in the mammalian proteome is unknown. Current catalogues of mammalian proteins exhibit an artefactual discontinuity at a length of 100 aa, so that protein abundance peaks just above this length and falls off sharply below it. To clarify the abundance of short proteins, we identify proteins in the FANTOM collection of mouse cDNAs by analysing synonymous and nonsynonymous substitutions with the computer program CRITICA. This analysis confirms that there is no real discontinuity at length 100. Roughly 10% of mouse proteins are shorter than 100 aa, although the majority of these are variants of proteins longer than 100 aa. We identify many novel short proteins, including a dark matter'' subset containing ones that lack detectable homology to other known proteins. Translation assays confirm that some of these novel proteins can be translated and localised to the secretory pathway.

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The particle-based lattice solid model developed to study the physics of rocks and the nonlinear dynamics of earthquakes is refined by incorporating intrinsic friction between particles. The model provides a means for studying the causes of seismic wave attenuation, as well as frictional heat generation, fault zone evolution, and localisation phenomena. A modified velocity-Verlat scheme that allows friction to be precisely modelled is developed. This is a difficult computational problem given that a discontinuity must be accurately simulated by the numerical approach (i.e., the transition from static to dynamical frictional behaviour). This is achieved using a half time step integration scheme. At each half time step, a nonlinear system is solved to compute the static frictional forces and states of touching particle-pairs. Improved efficiency is achieved by adaptively adjusting the time step increment, depending on the particle velocities in the system. The total energy is calculated and verified to remain constant to a high precision during simulations. Numerical experiments show that the model can be applied to the study of earthquake dynamics, the stick-slip instability, heat generation, and fault zone evolution. Such experiments may lead to a conclusive resolution of the heat flow paradox and improved understanding of earthquake precursory phenomena and dynamics. (C) 1999 Academic Press.

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Rotational degrees of freedom in Cosserat continua give rise to higher fracture modes. Three new fracture modes correspond to the cracks that are surfaces of discontinuities in the corresponding components of independent Cosserat rotations. We develop a generalisation of J- integral that includes these additional degrees of freedom. The obtained path-independent integrals are used to develop a criterion of crack propagation for a special type of failure in layered materials with sliding layers. This fracture propagates as a progressive bending failure of layers – a “bending crack that is, a crack that can be represented as a distribution of discontinuities in the layer bending. This situation is analysed using a 2D Cosserat continuum model. Semi-infinite bending crack normal to layering is considered. The moment stress concentrates along the line that is a continuation of the crack and has a singularity of the power − 1/4. A model of process zone is proposed for the case when the breakage of layers in the process of bending crack propagation is caused by a crack (microcrack in our description) growing across the layer adjacent to the crack tip. This growth is unstable (in the moment-controlled loading), which results in a typical descending branch of moment stress – rotation discontinuity relationship and hence in emergence of a Barenblatt-type process zone at the tip of the bending crack.

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A importância das micro e pequenas empresas na economia brasileira já é sentida desde há muito tempo, pois esse segmento é fundamental na geração de riqueza para a sociedade. Apesar da importância econômica, ainda persiste um elevado grau de descontinuidade nas mesmas, o que lhes outorga dificuldades de transporem os dois primeiros e mais críticos anos de existência. Esta pesquisa visa identificar os fatores determinantes da sobrevivência das micro e pequenas empresas do setor industrial na cidade de Santos. A relevância do estudo se intensifica em decorrência da cidade de Santos estar vivenciando um momento de desenvolvimento econômico impulsionado pelas descobertas de petróleo na camada do pré-sal. Isso poderá aumentar ainda mais o número de criação de MPEs, principalmente no setor industrial, e que provavelmente necessitarão de informações nas quais possam se espelhar. O estudo é de caráter exploratório e descritivo. Os dados foram colhidos por meio de uma pesquisa de campo com aplicação de um questionário baseado em quatro dimensões: empreendedorismo, ambiental, recursos financeiros e organização interna. A pesquisa apresentou como principais fatores de sobrevivência o tempo dedicado à empresa; a adequação dos produtos a demanda; a capacidade de assumir riscos e a liderança do gestor. A amostra de estudo foi definida por conveniência, constituída de MPEs pertencentes ao setor econômico industrial, pois é o mais aderente à cadeia de exploração de petróleo. Foram consideradas as empresas que ultrapassaram os dois primeiros anos de existência, de acordo com os critérios de avaliação de sobrevivência adotado pelo SEBRAE (2011).

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A discussão sobre a formação de Professores sempre foi um desafio, especialmente em se tratando dos caminhos e descaminhos acerca das práticas cotidianas e, muito mais, ainda hoje, com a inserção da tecnologia dentro das salas de aula. A pesquisa investigou se o uso da tecnologia favorece a interação professor-aluno e se isso se torna um facilitador na busca de novos conhecimentos, colaborando para a alteração da prática cotidiana. Para desenvolver tais discussões realizamos uma revisão da literatura e da legislação sobre a formação de professores no contexto brasileiro e sobre a formação de professores e as tecnologias. Elaboramos análises das ações do Governo Federal, privilegiando o contexto do Estado de São Paulo por ser o foco da nossa investigação. Para a realização da pesquisa de campo contamos com a colaboração de professores do Ensino Fundamental II e do Ensino Médio de Escolas Estaduais e os responsáveis das Oficinas Pedagógicas das Diretorias de Ensino dos Municípios de Santo André e Mauá para a aplicação de um questionário e realização de entrevistas de aprofundamento. Verificamos que os esforços de implantação de projetos desenvolvidos pela rede estadual esbarram na burocracia e na descontinuidade, provocadas pela mudança de administração, onde se priorizam os interesses pessoais em detrimento dos interesses coletivos. Em contrapartida, encontramos os formadores nas Diretorias de Ensino, que precisam atender todas as questões administrativas e políticas, e, ao mesmo tempo, darem conta da formação continuada dos professores, resolvendo problemas que, muitas vezes, estão longe de suas possibilidades e verificamos também que o uso da tecnologia na atividade docente ainda não é o esperado, ou seja, estes professores não fazem uso pedagógico do computador, porém, o uso aumentou sistematicamente, mas trazê-lo para a sala de aula ainda é um desafio e reflete a forma de agir e de pensar dos professores envolvidos no processo desta pesquisa.

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The blood types determination is essential to perform safe blood transfusions. In emergency situations isadministrated the “universal donor” blood type. However, sometimes, this blood type can cause incom-patibilities in the transfusion receptor. A mechatronic prototype was developed to solve this problem.The prototype was built to meet specific goals, incorporating all the necessary components. The obtainedsolution is close to the final system that will be produced later, at industrial scale, as a medical device.The prototype is a portable and low cost device, and can be used in remote locations. A computer appli-cation, previously developed is used to operate with the developed mechatronic prototype, and obtainautomatically test results. It allows image acquisition, processing and analysis, based on Computer Visionalgorithms, Machine Learning algorithms and deterministic algorithms. The Machine Learning algorithmsenable the classification of occurrence, or alack of agglutination in the mixture (blood/reagents), and amore reliable and a safer methodology as test data are stored in a database. The work developed allowsthe administration of a compatible blood type in emergency situations, avoiding the discontinuity of the“universal donor” blood type stocks, and reducing the occurrence of human errors in the transfusion practice.

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Gaussian Processes provide good prior models for spatial data, but can be too smooth. In many physical situations there are discontinuities along bounding surfaces, for example fronts in near-surface wind fields. We describe a modelling method for such a constrained discontinuity and demonstrate how to infer the model parameters in wind fields with MCMC sampling.