OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Vitelli” ,找到相关结果约98条。
Adolescências e identidades estéticas no cotidiano
Vitelli, Celso;
Educa??o em Revista , 2009, DOI: 10.1590/S0102-46982009000300004
Abstract: this article deals with the contemporary transformations that have put forward different views of important concepts, of which we highlight those of culture, consumption, esthetics, adolescence and art. these concepts, related to one another, have been approached having the adolescent as the center of the discussion. the study attempts to bring the quotidian of the adolescent to the center of the scene, valuing every action and speech as a means to enable the investigation of adolescence, whereas considering the speed of the changes that mark the present time and space. the investigation has unveiled a quotidian in which adolescence is celebrated in our culture, at the same time influenced by a society strongly directed towards consumption, interfering in the conception of social and cultural values constantly produced and reproduced.
Representa??es das masculinidades hegemónicas e subalternas no cinema
Análise Social , 2011,
Abstract: this article discusses part of the theory proposed by robert connell regarding masculinity as portrayed in the film crash, by paul haggis. we analyze two forms of masculinity in the film (hegemonic and subaltern) and their relationships to power, including the culture of the image, specifically, the language of film.
Representa es das masculinidades hegemónicas e subalternas no cinema Representations of masculine hegemony and subalterns in the cinema
Celso Vitelli
Análise Social , 2011,
Abstract: Este artigo discute parte da teoria proposta por Robert Connell sobre masculinidades, relacionando-a com situa es do filme Crash, de Paul Haggis. Analisam-se as diferentes masculinidades apresentadas no filme (hegemónica e subalterna) e as suas rela es com o poder, incluindo a cultura da imagem, especificamente na linguagem do cinema. This article discusses part of the theory proposed by Robert Connell regarding masculinity as portrayed in the film Crash, by Paul Haggis. We analyze two forms of masculinity in the film (hegemonic and subaltern) and their relationships to power, including the culture of the image, specifically, the language of film.
Attenuation of shear sound waves in jammed solids
Vincenzo Vitelli
Physics , 2010,
Abstract: We study the attenuation of long-wavelength shear sound waves propagating through model jammed packings of frictionless soft spheres interacting with repulsive springs. The elastic attenuation coefficient, $\alpha(\omega)$, of transverse phonons of low frequency, $\omega$, exhibits power law scaling as the packing fraction $\phi$ is lowered towards $\phi_c$, the critical packing fraction below which rigidity is lost. The elastic attenuation coefficient is inversely proportional to the scattering mean free path and follows Rayleigh law with $\alpha(\omega)\sim \omega^4 (\phi - \phi_c)^{-5/2}$ for $\omega$ much less than $\omega^* \sim (\phi - \phi_c)^{1/2}$, the characteristic frequency scale above which the energy diffusivity and density of states plateau. This scaling of the attenuation coefficient, consistent with numerics, is obtained by assuming that a jammed packing can be viewed as a mosaic composed of domains whose characteristic size $\ell^ * \sim (\phi-\phi_c) ^{-1/2}$ diverges at the transition.
Quantum Buckling
N. Upadhyaya,V. Vitelli
Physics , 2011, DOI: 10.1103/PhysRevE.84.040601
Abstract: We study the mechanical buckling of a two dimensional membrane coated with a thin layer of superfluid. It is seen that a singularity (vortex or anti-vortex defect) in the phase of the quantum order parameter, distorts the membrane metric into a negative conical singularity surface, irrespective of the defect sign. The defect-curvature coupling and the observed instability is in striking contrast with classical elasticity where, the in-plane strain induced by positive (negative) disclinations is screened by a corresponding positive (negative) conical singularity surface. Defining a dimensionless ratio between superfluid stiffness and membrane bending modulus, we derive conditions under which the quantum buckling instability occurs. An ansatz for the resulting shape of the buckled membrane is analytically and numerically confirmed.
Soft quantum vibrations of PT-symmetric nonlinear ion chain
Philipp Strack,Vincenzo Vitelli
Physics , 2013, DOI: 10.1103/PhysRevA.88.053408
Abstract: We theoretically study the quantum dynamics of transverse vibrations of a one-dimensional chain of trapped ions in harmonic potentials interacting via a Reggeon-type cubic nonlinearity that is nonunitary but preserves PT symmetry. We propose the notion of quantum fragility for the dissipative structural phase transition that spontaneously breaks the PT symmetry. In the quantum fragile regime, the nonlinearity dominates the response to mechanical perturbations and the chain supports neither the ordinary quantum phonons of a Luttinger liquid, nor the supersonic solitons that arise in classical fragile critical points in the absence of fluctuations. Quantum fluctuations, approximately captured within a one-loop renormalization group, give rise to mechanical excitations with a strongly momentum-dependent phonon velocity and dissipative spectral behavior. Observable signatures of the quantum fragile chain in trapped ion systems are discussed.
Anomalous coupling between topological defects and curvature
Vincenzo Vitelli,Ari Turner
Physics , 2004, DOI: 10.1103/PhysRevLett.93.215301
Abstract: We investigate a counterintuitive geometric interaction between defects and curvature in thin layers of superfluids, superconductors and liquid crystals deposited on curved surfaces. Each defect feels a geometric potential whose functional form is determined only by the shape of the surface, but whose sign and strength depend on the transformation properties of the order parameter. For superfluids and superconductors, the strength of this interaction is proportional to the square of the charge and causes all defects to be repelled (attracted) by regions of positive (negative) Gaussian curvature. For liquid crystals in the one elastic constant approximation, charges between 0 and $4\pi$ are attracted by regions of positive curvature while all other charges are repelled.
Crystals and liquid crystals confined to curved geometries
Vinzenz Koning,Vincenzo Vitelli
Physics , 2014,
Abstract: This review introduces the elasticity theory of two-dimensional crystals and nematic liquid crystals on curved surfaces, the energetics of topological defects (disclinations, dislocations and pleats) in these ordered phases, and the interaction of defects with the underlying curvature. This chapter concludes with two cases of three-dimensional nematic phases confined to spaces with curved boundaries, namely a torus and a spherical shell.
Geometric background charge: dislocations on capillary bridges
William Irvine,Vincenzo Vitelli
Physics , 2012,
Abstract: Recent experiments have shown that colloidal crystals confined to weakly curved capillary bridges introduce groups of dislocations organized into `pleats' as means to relieve the stress caused by the Gaussian curvature of the surface. We consider the onset of this curvature-screening mechanism, by examining the energetics of isolated dislocations and interstitials on capillary bridges with free boundaries. The boundary provides an essential contribution to the problem, akin to a background charge that "neutralizes" the unbalanced integrated curvature of the surface. This makes it favorable for topologically neutral dislocations and groups of dislocations - rather than topologically charged disclinations and scars - to relieve the stress caused by the unbalanced gaussian curvature of the surface. This effect applies to any crystal on a surface with non-vanishing integrated Gaussian curvature and stress-free boundary conditions. We corroborate the analytic results by numerically computing the energetics of a defected lattice of springs confined to surfaces with weak positive and negative curvature
Sparse Clustering of Functional Data
Davide Floriello,Valeria Vitelli
Statistics , 2015,
Abstract: We consider the problem of clustering functional data while jointly selecting the most relevant features for classification. This problem has never been tackled before in the functional data context, and it requires a proper definition of the concept of sparsity for functional data. Functional sparse clustering is here analytically defined as a variational problem with a hard thresholding constraint ensuring the sparsity of the solution. First, a unique solution to sparse clustering with hard thresholding in finite dimensions is proved to exist. Then, the infinite dimensional generalization is given and proved to have a unique solution. Both the multivariate and the functional version of sparse clustering with hard thresholding exhibits improvements on other standard and sparse clustering strategies on simulated data. A real functional data application is also shown.

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