CULTURAL ISSUES IN SUSTAINABLE SUPPLY CHAIN MANAGEMENT

This paper aims at contributing to literature debate on sustainable supply chain management by including the cultural factors as a strategic element. The focus in is on the role role of culture in the relationships of sustanible supply chain. The analysis sheds light on the CSR practices followed by MNC and provide a first contribute to identify the consideration of cultural issues as central theme to Sustainable supply chain management

From perfect to fractal transmission in spin chains

Perfect state transfer is possible in modulated spin chains, imperfections however are likely to corrupt the state transfer. We study the robustness of this quantum communication protocol in the presence of disorder both in the exchange couplings between the spins and in the local magnetic field. The degradation of the fidelity can be suitably expressed, as a function of the level of imperfection and the length of the chain, in a scaling form. In addition the time signal of fidelity becomes fractal. We further characterize the state transfer by analyzing the spectral properties of the Hamiltonian of the spin chain.Comment: 8 pages, 10 figures, published versio

Evolutionary importance of intraspecific variation in sex pheromones

Sex pheromones in many insect species are important species-recognition signals that attract conspecifics and inhibit attraction between heterospecifics; therefore, sex pheromones have predominantly been considered to evolve due to interactions between species. Recent research, however, is uncovering roles for these signals in mate choice, and that variation within and between populations can be drivers of species evolution. Variation in pheromone communication channels arises from a combination of context-dependent, condition-dependent, or genetic mechanisms in both signalers and receivers. Variation can affect mate choice and thus gene flow between individuals and populations, affecting species' evolution. The complex interactions between intraspecific and interspecific selection forces calls for more integrative studies to understand the evolution of sex pheromone communication.Peer reviewe

Entanglement at the quantum phase transition in a harmonic lattice

The entanglement properties of the phase transition in a two dimensional harmonic lattice, similar to the one observed in recent ion trap experiments, are discussed both, for finite number of particles and thermodynamical limit. We show that for the ground state at the critical value of the trapping potential two entanglement measures, the negativity between two neighbouring sites and the block entropy for blocks of size 1, 2 and 3, change abruptly. Entanglement thus indicates quantum phase transitions in general; not only in the finite dimensional case considered in [Phys. Rev. Lett. {\bf 93}, 250404 (2004)]. Finally, we consider the thermal state and compare its exact entanglement with a temperature entanglement witness introduced in [Phys. Rev. A {\bf 77} 062102 (2008)].Comment: extended published versio

Inhomogeneous Kibble-Zurek mechanism: vortex nucleation during Bose-Einstein condensation

The Kibble-Zurek mechanism is applied to the spontaneous formation of vortices in a harmonically trapped thermal gas following a temperature quench through the critical value for Bose-Einstein condensation. While in the homogeneous scenario vortex nucleation is always expected, we show that it can be completely suppressed in the presence of the confinement potential, whenever the speed of the spatial front undergoing condensation is lower than a threshold velocity. Otherwise, the interplay between the geometry and causality leads to different scaling laws for the density of vortices as a function of the quench rate, as we also illustrate for the case of a toroidal trapping potential.Comment: 11 pages, 3 figure

Entanglement evolution after connecting finite to infinite quantum chains

We study zero-temperature XX chains and transverse Ising chains and join an initially separate finite piece on one or on both sides to an infinite remainder. In both critical and non-critical systems we find a typical increase of the entanglement entropy after the quench, followed by a slow decay towards the value of the homogeneous chain. In the critical case, the predictions of conformal field theory are verified for the first phase of the evolution, while at late times a step structure can be observed.Comment: 15 pages, 11 figure

recommendations to optimise reporting of epidemiological studies on antimicrobial resistance and informing improvement in antimicrobial stewardship

Objectives To explore the accuracy of application of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) tool in epidemiological studies focused on the evaluation of the role of antibiotics in selecting resistance, and to derive and test an extension of STROBE to improve the suitability of the tool in evaluating the quality of reporting in these area. Methods A three-step study was performed. First, a systematic review of the literature analysing the association between antimicrobial exposure and acquisition of methicillin-resistant Staphylococcus aureus and/or multidrug-resistant Acinetobacter baumannii was performed. Second, articles were reviewed according to the STROBE checklist for epidemiological studies. Third, a set of potential new items focused on antimicrobial-resistance quality indicators was derived through an expert two-round RAND-modified Delphi procedure and tested on the articles selected through the literature review. Results The literature search identified 78 studies. Overall, the quality of reporting appeared to be poor in most areas. Five STROBE items, comprising statistical analysis and study objectives, were satisfactory in <25% of the studies. Informative abstract, reporting of bias, control of confounding, generalisability and description of study size were missing in more than half the articles. A set of 21 new items was developed and tested. The new items focused particularly on the study setting, antimicrobial usage indicators, and patients epidemiological and clinical characteristics. The performance of the new items in included studies was very low (<25%). Conclusions Our paper reveals that reporting in epidemiological papers analysing the association between antimicrobial usage and development of resistance is poor. The implementation of the newly developed STROBE for antimicrobial stewardship (AMS) tool should enhance appropriate study design and reporting, and therefore contribute to the improvement of evidence to be used for AMS programme development and assessment

Optimal control of atom transport for quantum gates in optical lattices

By means of optimal control techniques we model and optimize the manipulation of the external quantum state (center-of-mass motion) of atoms trapped in adjustable optical potentials. We consider in detail the cases of both non interacting and interacting atoms moving between neighboring sites in a lattice of a double-well optical potentials. Such a lattice can perform interaction-mediated entanglement of atom pairs and can realize two-qubit quantum gates. The optimized control sequences for the optical potential allow transport faster and with significantly larger fidelity than is possible with processes based on adiabatic transport.Comment: revised version: minor changes, 2 references added, published versio

Adiabatic dynamics of an inhomogeneous quantum phase transition: the case of z > 1 dynamical exponent

We consider an inhomogeneous quantum phase transition across a multicritical point of the XY quantum spin chain. This is an example of a Lifshitz transition with a dynamical exponent z = 2. Just like in the case z = 1 considered in New J. Phys. 12, 055007 (2010) when a critical front propagates much faster than the maximal group velocity of quasiparticles vq, then the transition is effectively homogeneous: density of excitations obeys a generalized Kibble-Zurek mechanism and scales with the sixth root of the transition rate. However, unlike for z = 1, the inhomogeneous transition becomes adiabatic not below vq but a lower threshold velocity v', proportional to inhomogeneity of the transition, where the excitations are suppressed exponentially. Interestingly, the adiabatic threshold v' is nonzero despite vanishing minimal group velocity of low energy quasiparticles. In the adiabatic regime below v' the inhomogeneous transition can be used for efficient adiabatic quantum state preparation in a quantum simulator: the time required for the critical front to sweep across a chain of N spins adiabatically is merely linear in N, while the corresponding time for a homogeneous transition across the multicritical point scales with the sixth power of N. What is more, excitations after the adiabatic inhomogeneous transition, if any, are brushed away by the critical front to the end of the spin chain.Comment: 10 pages, 6 figures, improved version accepted in NJ

Excitations in two-component Bose-gases

In this paper, we study a strongly correlated quantum system that has become amenable to experiment by the advent of ultracold bosonic atoms in optical lattices, a chain of two different bosonic constituents. Excitations in this system are first considered within the framework of bosonization and Luttinger liquid theory which are applicable if the Luttinger liquid parameters are determined numerically. The occurrence of a bosonic counterpart of fermionic spin-charge separation is signalled by a characteristic two-peak structure in the spectral functions found by dynamical DMRG in good agreement with analytical predictions. Experimentally, single-particle excitations as probed by spectral functions are currently not accessible in cold atoms. We therefore consider the modifications needed for current experiments, namely the investigation of the real-time evolution of density perturbations instead of single particle excitations, a slight inequivalence between the two intraspecies interactions in actual experiments, and the presence of a confining trap potential. Using time-dependent DMRG we show that only quantitative modifications occur. With an eye to the simulation of strongly correlated quantum systems far from equilibrium we detect a strong dependence of the time-evolution of entanglement entropy on the initial perturbation, signalling limitations to current reasonings on entanglement growth in many-body systems