Varying Alpha Monopoles

We study static magnetic monopoles in the context of varying alpha theories and show that there is a group of models for which the t'Hooft-Polyakov solution is still valid. Nevertheless, in general static magnetic monopole solutions in varying alpha theories depart from the classical t'Hooft-Polyakov solution with the electromagnetic energy concentrated inside the core seeding spatial variations of the fine structure constant. We show that Equivalence Principle constraints impose tight limits on the allowed variations of alpha induced by magnetic monopoles which confirms the difficulty to generate significant large-scale spatial variation of the fine structure constant found in previous works. This is true even in the most favorable case where magnetic monopoles are the source for these variations.Comment: 8 pages, 10 figures; Version to be published in Phys. Rev.

Deflection of (anti)ferromagnetic skyrmions at heterochiral interfaces

Devising magnetic nanostructures with spatially heterogeneous Dzyaloshinskii-Moriya interaction (DMI) is a promising pathway towards advanced confinement and control of magnetic skyrmions in potential devices. Here we discuss theoretically how a skyrmion interacts with a heterochiral interface using micromagnetic simulations and analytic arguments. We show that a heterochiral interface deflects the trajectory of ferromagnetic (FM) skyrmions, and that the extent of such deflection is tuned by the applied spin-polarized current and the difference in DMI across the interface. Further, we show that this deflection is characteristic for the FM skyrmion, and is completely absent in the antiferromagnetic (AFM) case. In turn, we reveal that the AFM skyrmion achieves much higher velocities than its FM counterpart, yet experiences far stronger confinement in nanoengineered heterochiral tracks, which reinforces AFM skyrmions as a favorable choice for skyrmion-based devices

Manipulation of Magnetic Skyrmions by Superconducting Vortices in Ferromagnet-Superconductor Heterostructures

Dynamics of magnetic skyrmions in hybrid ferromagnetic films harbors novel physical phenomena and holds promise for technological applications. In this work, we discuss the behavior of magnetic skyrmions when coupled to superconducting vortices in a ferromagnet-superconductor heterostructure. We use numerical simulations and analytic arguments to reveal broader possibilities for manipulating the skyrmion-vortex dynamic correlations in the hybrid system, that are not possible in its separated constituents. We explore the thresholds of particular dynamic phases, and quantify the phase diagram as a function of the relevant material parameters, applied current and induced magnetic torques. Finally, we demonstrate the broad and precise tunability of the skyrmion Hall-angle in presence of vortices, with respect to currents applied to either or both the superconductor and the ferromagnet within the heterostructure

A perceção do consumidor numa ótica relacional no contexto do consumo de produtos verdes

An exchange perspective of the relationship customer-grocery recognizes the important role that both the seller and the shopper assume in their relationships. Today consumers are increasingly considering green consumption, which has led to a situation where retailers expend substantial resources in response to this challenge. However, this consumption has remained lackluster justifying the need for greater knowledge about consumers’ behaviour. The purpose of this paper is to characterize groups of customers based on their perceptions of value, satisfaction with retailers as well as on risk perceived associated with their environmentally consumption practices. As a result of cluster analysis, we obtained a consumers’ typology differing in their relational benefits, satisfaction and risks perceptions. Some suggestions are given to retailers and also recommendations about the need to closely consider their product offerings to ascertain what aspects contribute to the value considered by shoppers.info:eu-repo/semantics/publishedVersio

Collective modes in relativistic npe matter at finite temperature

Isospin and density waves in neutral neutron-proton-electron (npe) matter are studied within a relativistic mean-field hadron model at finite temperature with the inclusion of the electromagnetic field. The dispersion relation is calculated and the collective modes are obtained. The unstable modes are discussed and the spinodals, which separate the stable from the unstable regions, are shown for different values of the momentum transfer at various temperatures. The critical temperatures are compared with the ones obtained in a system without electrons. The largest critical temperature, 12.39 MeV, occurs for a proton fraction y_p=0.47. For y_p=0.3 we get $T_{cr}$ =5 MeV and for y_p>0.495 $T_cr\lesssim 8$ MeV. It is shown that at finite temperature the distillation effect in asymmetric matter is not so efficient and that electron effects are particularly important for small momentum transfers.Comment: 10 pages, 6 figure

How costumers' way of life influence the value co-creation

Purpose: This article is a contribution to the understanding of how value arises in well-established markets, and under which circumstances actors integrate resources from different service ecosystems to generate value. To understand this phenomenon, it is fundamental to consider which practices are performed by customers to co-create value and how they do so. Design/Methodology/Approach: Using a qualitative approach, the study provides fresh empirical insight into well-established market processes of value creation. After a literature review an ethnographic approach was chosen in order to understand how co-creation processes occur in the empirical setting of an international restaurant chain. Several observations, conversations and semi-structured interviews were undertaken concerning the analysis of the topic under study. Findings: The results show that even in a well-established market, a provider must consider individual customers’ distinct needs, present in their daily practices, to be able to assist them in the value creation process. It is argued that the practice styles are the building blocks for prevailing ways of life that actors assume, according to the context in which they are, to integrate resources. Practical implications: The study includes implications for service providers of a well-founded market for facilitating value co-creation along with customers and fulfils the need to better understand this phenomenon. Originality/Value: Recent studies call for empirical evidence on co-creation processes in mature markets, accordingly, this study brings an additional understanding on how actors, depending on the context, adopt different ways of life that require unique resources, which activate to achieve what they want, in order to establish room for co-creation.info:eu-repo/semantics/publishedVersio