Friedel sum rule for an interacting multiorbital quantum dot

A generalized Friedel sum rule is derived for a quantum dot with internal orbital and spin degrees of freedom. The result is valid when all many-body correlations are taken into account and it links the phase shift of the scattered electron to the displacement of its SPECTRAL density into the dot.Comment: RevTeX 4.0, 5 page

Users' social-interaction needs while shopping via online sales configurators

The growing adoption of social web technologies such as social software (SSW) in online configuration environments has enabled the possibility of supporting configurator users in interacting digitally with real people while they are shopping for customized products. Previous research has identified that online sales configurators (OSCs) are currently connected to SSW with different modalities to provide configurator users with a variety of options to digitally interact with real people. Enriching the configuration environment with social-interaction tools has engendered the phenomenon of social-product customization. Recent studies considered the social product-customization by investigating the impact that community feedback and social comparisons has on configurator user. However, the OSCs users' need to interact with different referents during their configuration process, and whether the SSW-OSCs connections respond to this need are still unsearched. To address this gap, the present study explores (a) whether users experience the need to interact with different referents while shopping via OSCs and (b) which interaction modalities users are looking for. By considering 943 configuration experiences from 189 users of 378 OSCs for various consumer goods, the present study finds that the need for social interaction by OSC users is highly relevant. Moreover, OSC users perceive the need to interact with different referents during different stages of the configuration process, and, depending on the referent with whom they wish to interact, they are interested in different interaction modalities in terms of how and where those interactions take place. These findings imply that mass customizers may leverage their customers' need to interact with real people while shopping online via OSCs in order to better engage their actual and potential customers

The gap exponent of XXZ model in a transverse field

We have calculated numerically the gap exponent of the anisotropic Heisenberg model in the presence of the transverse magnetic field. We have implemented the modified Lanczos method to obtain the excited states of our model with the same accuracy of the ground state. The coefficient of the leading term in the perturbation expansion diverges in the thermodynamic limit (N --> infinity). We have obtained the relation between this divergence and the scaling behaviour of the energy gap. We have found that the opening of gap in the presence of transverse field scales with a critical exponent which depends on the anisotropy parameter (Delta). Our numerical results are in well agreement with the field theoretical approach in the whole range of the anisotropy parameter, -1 < Delta < 1.Comment: 6 pages and 4 figure

Genetic algorithm optimization of entanglement

We present an application of a genetic algorithmic computational method to the optimization of the concurrence measure of entanglement for the cases of one dimensional chains, as well as square and triangular lattices in a simple tight-binding approach in which the hopping of electrons is much stronger than the phonon dissipationComment: 26 pages with 13 figures, based on Chapter 3 of the Master thesis of the first author defended at IPICyT, San Luis Potosi, Mx, on 22nd of February 2006, similar to the published version [Fig. 5 left out but contains the Appendix figure

Correlated Nanoscopic Josephson Junctions

We discuss correlated lattice models with a time-dependent potential across a barrier and show how to implement a Josephson-junction-like behavior. The pairing occurs by a correlation effect enhanced by the symmetry of the system. In order to produce the effect we need a mild distortion which causes avoided crossings in the many-body spectrum. The Josephson-like response involves a quasi-adiabatic evolution in the time-dependent field. Besides, we observe an inverse-Josephson (Shapiro) current by applying an AC bias; a supercurrent in the absence of electromotive force can also be excited. The qualitative arguments are supported by explicit exact solutions in prototype 5-atom clusters with on-site repulsion. These basic units are then combined in ring-shaped systems, where one of the units sits at a higher potential and works as a barrier. In this case the solution is found by mapping the low-energy Hamiltonian into an effective anisotropic Heisenberg chain. Once again, we present evidence for a superconducting flux quantization, i.e. a Josephson-junction-like behavior suggesting the build-up of an effective order parameter already in few-electron systems. Some general implications for the quantum theory of transport are also briefly discussed, stressing the nontrivial occurrence of asymptotic current oscillations for long times in the presence of bound states.Comment: 12 pages, 2 figures, to appear in J. Phys. - Cond. Ma

A user-centric execution environment for <em>CineGrid</em> workloads

The abundance and heterogeneity of IT resources available, together with the ability to dynamically scale applications poses significant usability issues to users. Without understanding the performance profile of available resources users are unable to efficiently scale their applications in order to meet performance objectives. High quality media collaborations, like CineGrid, are one example of such diverse environments where users can leverage dynamic infrastructures to move and process large amounts of data. This paper describes our user-centric approach to executing high quality media processing workloads over dynamic infrastructures. Our main contribution is the CGtoolkit environment, an integrated system which aids users cope with the infrastructure complexity and large data sets specific to the digital cinema domain

PM emissions from a BR basin and impact assessment on air quality

The article deals with the emission of fugitive dust from a major BR (Bauxite Residue) basin located in the south-west of Sardinia, where the prospect of a change in the storage practices is likely to cause the increase of PM (Particulate Matter) pollution in the surrounding region. In fact, other natural and anthropic sources already provide a variable contribution in terms of airborne dust concentration in the same territory. In accordance with the procedures established by the Directive 2011/92 (EIA Directive - Environmental Impact Assessment), the data recorded by a monitoring network located in the SulcisIglesiente sub-region has been taken into consideration in order to define the ante-operam condition of the potential impact area. The additional contribution of the red mud basin has been simulated with the atmospheric dispersion model proposed by US EPA (Environmental Protection Agency). The expected whole concentration of the PM10, which includes both the pre-existing sources and the additional contribution of the red mud basin, has been estimated and compared with the limit values established by the Directive 2008/50/EC (Ambient air quality and cleaner air for Europe)