957 resultados para Sublattice symmetry breaking


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With over 30 years of tradition, breaking in Germany provides fascinating insights into the learning of dance in Hip Hop culture, reaching from informal street learning to the introduction of courses in educational institutions. This article draws information from a qualitative empirical study based on the Grounded Theory Methodology. The study asked subjects ranging from first-generation German B-Boys and B-Girls to teenage students about how they have learned and currently learn to break. The interview material reveals a rich and self-regulated learning culture with strong impact on protagonists. A synergy of social, aesthetic, and ethical principles seems to be characteristic, creating a gravitational field of learning with a unique and complex form of imitation at its core. (DIPF/Orig.)

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Aiming at the evaluation of the impact of the ionic liquids (ILs) cation symmetry on their phase behaviour, in this work, novel mutual solubilities with water of the symmetric series of [C(n)C(n)im][NTf2] (with n=1-5) were determined and compared with their isomeric forms of the asymmetric [C(n)C(1)im][NTf2] group. While the solubility of isomeric ILs in water was found to be similar, the solubility of water in ILs follows the same trend up to a maximum cation alkyl side chain length. For n >= 4 in [C(n)C(n)im][NTf2] the solubility of water in the asymmetric ILs is slightly higher than that observed in the symmetric counterparts. The thermodynamic properties of solution and solvation derived from the experimental solubility data of ILs in water at infinite dilution, namely the Gibbs energy, enthalpy and entropy were used to evaluate the cation symmetry effect on the ILs solvation. It is shown that the solubility of ILs in water is entropically driven and highly influenced by the cation size. Accordingly, it was found that the ILs solubility in water of both symmetric and asymmetric series depends on their molecular volume. Based on these findings, a linear correlation between the logarithm of the solubility of ILs in water and their molar volume is here proposed for the [NTf2]-based ILs at a fixed temperature.

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In this article we consider the a posteriori error estimation and adaptive mesh refinement of discontinuous Galerkin finite element approximations of the bifurcation problem associated with the steady incompressible Navier-Stokes equations. Particular attention is given to the reliable error estimation of the critical Reynolds number at which a steady pitchfork or Hopf bifurcation occurs when the underlying physical system possesses reflectional or Z_2 symmetry. Here, computable a posteriori error bounds are derived based on employing the generalization of the standard Dual-Weighted-Residual approach, originally developed for the estimation of target functionals of the solution, to bifurcation problems. Numerical experiments highlighting the practical performance of the proposed a posteriori error indicator on adaptively refined computational meshes are presented.

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Breaking through the Margins: Pushing Sociopolitical Boundaries Through Historic Preservation” explores the ways in which contemporary grassroots organizations are adapting historic preservation methods to protect African American heritage in communities that are on the brink of erasure. This project emerges from an eighteen-month longitudinal study of three African American preservation organizations—one in College Park, Maryland and two in Houston, Texas—where gentrification or suburban sprawl has all but decimated the physical landscape of their communities. Grassroots preservationists in Lakeland (College Park, Maryland), St. John Baptist Church (Missouri City, Texas), and Freedmen’s Town (Houston, Texas) are involved in pushing back against preservation practices that do not, or tend not, to take into consideration the narratives of African American communities. I argue, these organizations practice a form of preservation that provides immediate and lasting effects for communities hovering at the margins. This dissertation seeks to outline some of the major methodological approaches taken by Lakeland, St. John, and Freedmen’s Town. The preservation efforts put forth by the grassroots organizations in these communities faithfully work to remind us that history without preservation is lost. In taking on the critical work of pursuing social justice, these grassroots organizations are breaking through the margins of society using historic preservation as their medium.

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Horacio Quiroga (1878-1937) es uno de los escritores más logrados por sus cuentos y sigue siendo aclamado por la crítica en el mundo de habla hispana. Sus obras son consideradas parte del canon dentro de la tradición literaria sudamericana. Algunas de sus historias más renombradas circulan para la audiencia más global, publicadas en diversas colecciones y antologías que han sido posibles por haber sido traducidas al inglés. La versión más disponible en inglés es la traducción realizada por Margaret Sayers Peden ((1976) 2004), Quiroga habla por medio de las elecciones que realizó la traductora. Sin embargo, cabe preguntarse: ¿es este el Horacio Quiroga que las generaciones anteriores conocieron, apreciaron y alabaron? ¿Han logrado sobrevivir a la operación traductológica en inglés su prosa exquisita y su narrativa fotográfica para los lectores en inglés? Este artículo intenta abordar temas centrales de la traducción literaria en cuanto los textos de Quiroga y de Sayers Peden. También trata sobre las estrategias de domesticación, sobre cómo la manipulación del original puede traer consecuencias para la legibilidad, además la importancia de conocer bien los rasgos sociopolíticos y las características geográficas y, no menor, la responsabilidad profesional implícita en el rol del traductor como mediador cultural ya que selecciona, edita y publica literatura que no pertenece a lo convencional y establecido.

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Dust attenuation affects nearly all observational aspects of galaxy evolution, yet very little is known about the form of the dust-attenuation law in the distant universe. Here, we model the spectral energy distributions of galaxies at z ~ 1.5–3 from CANDELS with rest-frame UV to near-IR imaging under different assumptions about the dust law, and compare the amount of inferred attenuated light with the observed infrared (IR) luminosities. Some individual galaxies show strong Bayesian evidence in preference of one dust law over another, and this preference agrees with their observed location on the plane of infrared excess (IRX, L_TIR/L_UV) and UV slope (β). We generalize the shape of the dust law with an empirical model, A_ λ,σ =E(B-V)k_ λ (λ / λ v)^ σ where k_λ is the dust law of Calzetti et al., and show that there exists a correlation between the color excess E(B-V) and tilt δ with δ =(0.62±0.05)log(E(B-V))+(0.26±0.02). Galaxies with high color excess have a shallower, starburst-like law, and those with low color excess have a steeper, SMC-like law. Surprisingly, the galaxies in our sample show no correlation between the shape of the dust law and stellar mass, star formation rate, or β. The change in the dust law with color excess is consistent with a model where attenuation is caused by scattering, a mixed star–dust geometry, and/or trends with stellar population age, metallicity, and dust grain size. This rest-frame UV-to-near-IR method shows potential to constrain the dust law at even higher redshifts (z>3).

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This thesis investigates the place-names of four parishes in Berwickshire and compares coastal and inland naming patterns. Berwickshire is a large county that borders on northern England and historically formed part of Anglo-Saxon Northumbria. Partly due to the survival of extensive archives from the medieval priory of Coldingham, preserved in Durham Cathedral Archives, this county holds some of Scotland’s earliest recorded place- names. The parishes that form the research area are grouped together in the north-east of the county. Two of these parishes, Abbey St Bathans and Bunkle & Preston, are inland, and two, Cockburnspath and Coldingham, have extensive coastlines. The diversity of this group of parishes allows a comparative study of the place-names of coastal and inland areas to be undertaken. The topography of Berwickshire’s thirty-two parishes is very varied, and the four parishes have been chosen to reflect this range of landscapes. The place-names within the four parishes examined in this thesis derive almost exclusively from Old English, Older Scots, Modern Scots including Standard Scottish English, with a small minority derived from Old Norse, Gaelic, and Brittonic. The chronology of Old English, Older Scots, and Modern Scots is defined as given in the Concise Scots Dictionary: Old English is the period up to 1100, Older Scots is the period 1100-1700, and Modern Scots is the period 1700 onwards (CSD, 1985: xiii). Often with place-names it is not possible to give a precise dating for the coining of a toponym. For the purposes of this study, the language label given for a toponym is that of the date of the earliest record of the place-name with earlier linguistic evidence supplementing discussion. This thesis focuses on the names of topographic features, for example hills, rocks and woodland, and the role of perception in their naming. In order to compare the role of perception in inland and coastal naming, this thesis includes a diachronic study of the toponymy of the research area, along with two case studies. The first of these is a study of the toponymy of relief features, which focuses on generic elements in order to compare the perception of one type of referent in the two environments. The second is a study of the ‘colour’ category, which focuses on qualifying elements in order to compare the use of colour terms in the two environments. This thesis is the first comparative study of inland and coastal place-names, and it is one of the first to investigate new ways of using fieldwork as a central part of its methodology. In doing so it proposes innovative and nuanced ways to understand the toponymy of diverse landscapes within a community.

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Either with words or images, the expression of feelings results, in a work of art, in communication. If this was not the case, the work would not require a spectator or a reader. And if words suggest images from what its author refers to and a countless number of figurations may happen, the images from a film reveal what you can see. We are often left with "just" the space for those facts to shape up as possible meanings to which we react with emotion or with a particular intellectualization, finding exactly what we call readings or interpretations. Starting from a definition of literature that we see spilled in the work prospected from the polysystem theory by Itamar Even-Zohar from the Porter Institute for Poetics and Semiotics (University of Tel-Aviv), we consider the dynamic character of every cultural moment/object. This is how a literary reading, that is to apply some of the methodologies in the interpretation of a literary work, is allowed to extend to other cultural objects. This is what we are going to do with Lars von Trier's Breaking the Waves, a landmark in cinema for what the movement and manifest Dogma 95 represents, but that for a literature reader particularly focused on the narration of love in its different manifestations - in which sex and faith are included - a corpus is revealed, filled with interpretative possibilities and emotional reactions, important condiments particularly to the spectator and/or interested reader.

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A broad sector of literature focuses on the relationship between fluid dynamics and gravitational systems. This thesis presents results that suggest the existence of a new kind of fluid/gravity duality not based on the holographic principle. The goal is to provide tools that allow us to systematically unearth hidden symmetries for reduced models of cosmology. The focus is on the field space of these models, i.e. the superspace. In fact, conformal isometries of the supermetric leave geodesics in the field space unaltered; this leads to symmetries of the models. An innovative aspect is the use of the Eisenhart-Duval’s lift. Using this method, systems constrained by a potential can be treated as free ones. Moreover, charges explicitly dependent on time, i.e. dynamical, can be found. A detailed analysis is carried out on three basic models of homogenous cosmology: i) flat Friedmann-Lemaître-Robertson-Walker’s isotropic universe filled with a massless scalar field; ii) Schwarzschild’s black hole mechanics and its extension to vacuum (A)dS gravity; iii) Bianchi’s anisotropic type I universe with a massless scalar field. The results show the presence of a hidden Schrödinger’s symmetry which, being intrinsic to both Navier-Stokes’ and Schrödinger’s equations, indicates a correspondence between cosmology and hydrodynamics. Furthermore, the central extension of this algebra explicitly relates two concepts. The first is the number of particles coming from the fluid picture; while the second is the ratio between the IR and UV cutoffs that weighs how much a theory has of “classical” over “quantum”. This suggests a spacetime that emerges from an underlying world which is described by quantum building blocks. These quanta statistically conspire to appear as gravitational phenomena from a macroscopic point of view.

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The role of orbital differentiation on the emergence of superconductivity in the Fe-based superconductors remains an open question to the scientific community. In this investigation, we employ a suitable microscopic spin probe technique, namely Electron Spin Resonance (ESR), to investigate this issue on selected chemically substituted BaFe2As2 single crystals. As the spin-density wave (SDW) phase is suppressed, we observe a clear increase of the Fe 3d bands anisotropy along with their localization at the FeAs plane. Such an increase of the planar orbital content is interestingly independent of the chemical substitution responsible for suppressing the SDW phase. As a consequence, the magnetic fluctuations in combination with this particular symmetry of the Fe 3d bands are propitious ingredients for the emergence of superconductivity in this class of materials.

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The premature fusion of unilateral coronal suture can cause a significant asymmetry of the craniofacial skeleton, with an oblique deviation of the cranial base that negatively impacts soft tissue facial symmetry. The purpose of this study was to assess facial symmetry obtained in patients with unilateral coronal synostosis (UCS) surgically treated by 2 different techniques. We hypothesized that nasal deviation should not be addressed in a primary surgical correction of UCS. Consecutive UCS patients were enrolled in a prospective study and randomly divided into 2 groups. In group 1, the patients underwent total frontal reconstruction and transferring of onlay bone grafts to the recessive superior orbital rim (n = 7), and in group 2, the patients underwent total frontal reconstruction and unilateral fronto-orbital advancement (n = 5). Computerized photogrammetric analysis measured vertical and horizontal axis of the nose and the orbital globe in the preoperative and postoperative periods. Intragroup and intergroup comparisons were performed. Intragroup preoperative and postoperative comparisons showed a significant (all P < 0.05) reduction of the nasal axis and the orbital-globe axis in the postoperative period in the 2 groups. Intergroup comparisons showed no significant difference (all P > 0.05). Facial symmetry was achieved in the patients with UCS who underwent surgery regardless of surgical approach evaluated here. Our data showed a significant improvement in nasal and orbital-globe deviation, leading us to question the necessity of primary nasal correction in these patients.

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We report a combined study of external pressure and Cu-substitution on BaFe2As2 single crystals grown by the in-flux technique. At ambient pressure, the Cu-substitution is known to suppress the spin density wave (SDW) phase in pure BaFe2As2(TSDW ≈ 140 K) and to induce a superconducting (SC) dome with a maximum transition temperature [Formula: see text]. This [Formula: see text] is much lower than the Tc ∼ 15-28 K achieved in the case of Ru, Ni and Co substitutions. Such a lower Tc is attributed to a Cu(2+) magnetic pair-breaking effect. The latter is strongly suppressed by applied pressure, as shown herein, Tc can be significantly enhanced by applying high pressures. In this work, we investigated the pressure effects on Cu(2+) magnetic pair-breaking in the BaFe2-xCuxAs2 series. Around the optimal concentration (xopd = 0.11), all samples showed a substantial increase of Tc as a function of pressure. Yet for those samples with a slightly higher doping level (over-doped regime), Tc presented a dome-like shape with maximum Tc ≃ 8 K. Remarkably interesting, the under-doped samples, e.g. x = 0.02 display a maximum pressure induced Tc ≃ 30 K which is comparable to the maximum Tc's found for the pure compound under external pressures. Furthermore, the magnetoresistance effect as a function of pressure in the normal state of the x = 0.02 sample also presented an evolution consistent with the screening of the Cu(2+) local moments. These findings demonstrate that the Cu(2+) magnetic pair-breaking effect is completely suppressed by applying pressure in the low concentration regime of Cu(2+) substituted BaFe2As2.

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Crystalline structures of zeolites can be studied using different representations: the internal symmetry obtained by X-Ray or neutron diffraction crystallography techniques or a systematic analysis of the basic structural units which can be arranged to build the geometries of each kind of zeolite. In this work the basic concepts of three building units, SBU (Secondary Building Units), SSU (Structural SubUnits) and PBU (Periodic Building Units) are presented. The properties of the resulting crystalline structures are discussed (pores, cavities, channels), describing the influence of each one of these properties in processes of physical-chemical interest. Representative case studies of known zeolite crystalline structures are also discussed in terms of their space group classification.

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Universidade Estadual de Campinas . Faculdade de Educação Física