Boundary versus bulk behavior of time-dependent correlation functions in one-dimensional quantum systems

We study the influence of reflective boundaries on time-dependent responses of one-dimensional quantum fluids at zero temperature beyond the low-energy approximation. Our analysis is based on an extension of effective mobile impurity models for nonlinear Luttinger liquids to the case of open boundary conditions. For integrable models, we show that boundary autocorrelations oscillate as a function of time with the same frequency as the corresponding bulk autocorrelations. This frequency can be identified as the band edge of elementary excitations. The amplitude of the oscillations decays as a power law with distinct exponents at the boundary and in the bulk, but boundary and bulk exponents are determined by the same coupling constant in the mobile impurity model. For nonintegrable models, we argue that the power-law decay of the oscillations is generic for autocorrelations in the bulk, but turns into an exponential decay at the boundary. Moreover, there is in general a nonuniversal shift of the boundary frequency in comparison with the band edge of bulk excitations. The predictions of our effective field theory are compared with numerical results obtained by time-dependent density matrix renormalization group (tDMRG) for both integrable and nonintegrable critical spin-$S$ chains with $S=1/2$, $1$ and $3/2$.Comment: 20 pages, 12 figure

Gravitomagnetic Moments of the Fundamental Fields

The quadratic form of the Dirac equation in a Riemann spacetime yields a gravitational gyromagnetic ratio \kappa_S = 2 for the interaction of a Dirac spinor with curvature. A gravitational gyromagnetic ratio \kappa_S = 1 is also found for the interaction of a vector field with curvature. It is shown that the Dirac equation in a curved background can be obtained as the square--root of the corresponding vector field equation only if the gravitational gyromagnetic ratios are properly taken into account.Comment: 8 pages, RevTeX Style, no figures, changed presentation -- now restricted to fields of spin 0, 1/2 and 1 -- some references adde

Vertical force production in soccer: mechanical aspects and applied training strategies

Vertical force production (VFP) is widely recognized as a critical determinant of performance in a series of soccer-specific activities, such as sprinting, jumping, and changing direction. Therefore, practitioners are constantly seeking better and more effective strategies to improve VFP in professional soccer players. This article analyzes the mechanical aspects associated with the actual role played by VFP in elite soccer, and also examines and highlights the training considerations related to its appropriate and effective development during modern soccer seasons

Magnetically-controlled impurities in quantum wires with strong Rashba coupling

We investigate the effect of strong spin-orbit interaction on the electronic transport through non-magnetic impurities in one-dimensional systems. When a perpendicular magnetic field is applied, the electron spin polarization becomes momentum-dependent and spin-flip scattering appears, to first order in the applied field, in addition to the usual potential scattering. We analyze a situation in which, by tuning the Fermi level and the Rashba coupling, the magnetic field can suppress the potential scattering. This mechanism should give rise to a significant negative magnetoresistance in the limit of large barriers.Comment: 4 pages, 2 figure

Non universality of entanglement convertibility

Recently, it has been suggested that operational properties connected to quantum computation can be alternative indicators of quantum phase transitions. In this work we systematically study these operational properties in 1D systems that present phase transitions of different orders. For this purpose, we evaluate the local convertibility between bipartite ground states. Our results suggest that the operational properties, related to non-analyticities of the entanglement spectrum, are good detectors of explicit symmetries of the model, but not necessarily of phase transitions. We also show that thermodynamically equivalent phases, such as Luttinger liquids, may display different convertibility properties depending on the underlying microscopic model.Comment: 5 pages + references, 4 figures - improved versio

Optimal alarm systems for FIAPARCH processes

In this work, an optimal alarm system is developed to predict whether a financial time series modeled via Fractionally Integrated Asymmetric Power ARCH (FIAPARCH) models, up/downcrosses some particular level and give an alarm whenever this crossing is predicted. The paper presents classical and Bayesian methodology for producing optimal alarm systems. Both methodologies are illustrated and their performance compared through a simulation study. The work finishes with an empirical application to a set of data concerning daily returns of the Sao Paulo Stock Market

Lesion size, latent period and sporulation on leaf discs as indicators of resistance of Hevea to Microcyclus ulei.

This study investigated lesion sizes, latent periods and sporulation of leaf discs as indicators of resistance of Hevea to Microcyclus ulei. There were clonal differences in the rate of development of mycelium and appearance of lesions, sizes of lesions, latent period and the quantity of conidia produced on discs of Hevea leaves. There was a positive correlation between conidial production and lesion size, and negative correlations existed between conidial production and latent period and lesion size and latent period. Latent period and sporulation are also important components for assessment of resistance. Clones GT 711, RRIM 501, CNS AM 7701, SIAL 842 and SIAL 263 possessed relatively smaller lesions, longer latent periods and reduced sporulation. On these clones, the differences in lesion size were significant between clonesbut not between races of Microcyclus ulei. However, diffences in conidial production between clones, races and the interaction between clones and races were significant

Introduction: representations of India at home and abroad

This dossier makes an original contribution to the semantic analysis of the representations on India. It aims to broaden the academic debate on South Asian studies by focusing on the cultural practices of both Indians and migrants and on their representations of India, a much neglected subject in the literature. The five articles it comprises examine three dimensions of representations about India. One concerns the connection between tourism and religion, and the transformation of representations of Portuguese presence in Goa. Another dimension addresses the representations of the lifestyle migrants in India and the population in Portugal, notably regarding the consumption of an Indian and Bollywood lifestyle. A third dimension focuses on South Asian migrants in Portugal embeddedness, through economic processes. The main finding that brings these papers together is that the importance given by the different actors to the cultural representations about India is so strong that it defines decisions for their life experiences. These cultural representations are heterogeneous, circulating with divergent meanings in India and abroad, grounded on different images of past and present. The articles explore their production and uses in various settings