934 resultados para string breaking


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A realistic model describing a black string-like object in an expanding Universe is analyzed in the context of the McVittie's solution of the Einstein field equations. The bulk metric near the brane is provided analogously to previous solutions for black strings. In particular, we show that at least when the Hubble parameter on the brane is positive, a black string-like object seems to play a fundamental role in the braneworld scenario, generalizing the standard black strings in the context of a dynamical brane. © 2013 Elsevier B.V.

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We revisit the dynamical system-based approach of spherically symmetric vacuum braneworlds, pointing out and studying the existence of a transcritical bifurcation as the dark pressure parameter changes its sign, we analyze some consequences of not discard the brane cosmological constant. For instance, it is noteworthy that the existence of an isothermal state equation between the dark fluid parameters cannot be obtained via the requirement of a quasi-homologous symmetry of the vacuum. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica.

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Prepared by ECLAC for the twelfth session of the Regional Conference on Women in Latin America and the Caribbean, this document systematizes and describes various dimensions that shape the way the region's women participate in the labour market and how they access and use the different elements of the digital economy. Information and communications technologies (ICTs); provide essential support across all economic, political, cultural and social activity, as well as being a production sector in their own right. As such, they are potential allies in the drive to achieve equality by helping reduce the gender inequities which constitute not only a gender digital gap but also a social divide. Public policies on gender equality must take into account the key and interconnected dimensions of economy, well-being and technology if they are to be capable of providing an ambitious and innovative response to the challenges of today's society. The core argument in the reflection on ICTs and gender equality thus has to do with how women engage in processes of change and sustainable development in the countries, which cannot be achieved without equal participation by men and women. From this perspective, the gender digital gap offers a specific opportunity to tackle gender inequalities in the region.

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Prefacio Prepared by ECLAC for the twelfth session of the Regional Conference on Women in Latin America and the Caribbean, this document systematizes and describes various dimensions that shape the way the region's women participate in the labour market, and how they access and use the different elements of the digital economy. Information and communications technologies (ICTs) provide essential support across all economic, political, cultural and social activity, as well as being a production sector in their own right. As such, they are potential allies in the drive to achieve equality by helping reduce the gender inequities which constitute not only a gender digital gap but also a social divide. Public policies on gender equality must take into account the key and interconnected dimensions of economy, well-being and technology if they are to be capable of providing an ambitious and innovative response to the challenges of today's society. The core argument in the reflection on ICTs and gender equality thus has to do with how women engage in processes of change and sustainable development in the countries, which cannot be achieved without equal participation by men and women. From this perspective, the gender digital gap offers a specific opportunity to tackle gender inequalities in the region.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Física - IFT

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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We elucidate the close relationship between spontaneous time-reversal symmetry breaking and the physics of excitonic instabilities in strongly correlated multiband systems. The underlying mechanism responsible for the spontaneous breaking of time-reversal symmetry in a many-body system is closely related to the Cooper-like pairing instability of interband particle-hole pairs involving higher-order symmetries. Studies of such pairing instabilities have, however, mainly focused on the mean-field aspects of the virtual exciton condensate, which ignores the presence of the underlying collective Fermi-liquid excitations. We show that this relationship can be exploited to systematically derive the coupling of the condensate order parameter to the intraband Fermi-liquid particle-hole excitations. Surprisingly, we find that the static susceptibility is negative in the ordered phase when the coupling to the Fermi-liquid collective excitations are included, suggesting that a uniform condensate of virtual excitons, with or without time-reversal breaking, is an unstable phase at T = 0.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The evolution of surface water waves in finite depth under wind forcing is reduced to an antidissipative Korteweg-de Vries-Burgers equation. We exhibit its solitary wave solution. Antidissipation accelerates and increases the amplitude of the solitary wave and leads to blow-up and breaking. Blow-up occurs in finite time for infinitely large asymptotic space so it is a nonlinear, dispersive, and antidissipative equivalent of the linear instability which occurs for infinite time. Due to antidissipation two given arbitrary and adjacent planes of constant phases of the solitary wave acquire different velocities and accelerations inducing breaking. Soliton breaking occurs in finite space in a time prior to the blow-up. We show that the theoretical growth in amplitude and the time of breaking are both testable in an existing experimental facility.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)