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.

Evolution of the fine-structure constant in the non-linear regime

We study the evolution of the fine-structure constant, $\alpha$, induced by non-linear density perturbations in the context of the simplest class of quintessence models with a non-minimal coupling to the electromagnetic field, in which the two available free functions (potential and gauge kinetic function) are Taylor-expanded up to linear order. We show that the results obtained using the spherical infall model for an infinite wavelength inhomogeneity are inconsistent with the results of a local linearized gravity study and we argue in favour of the second approach. We also discuss recent claims that the value of $\alpha$ inside virialised regions could be significantly different from the background one on the basis of these findings.Comment: 5 pages, 3 figure

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

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

Valor de uso num contexto B2B na logística no sector alimentar

The main objective of this research is to understand the way a provider participates and contributes in the value co-creation process and identify the drivers that contribute to it. Given the nature of the phenomena under study a qualitative research approach was chosen to conduct this study. To reach a deep understanding about the phenomena in the B2B empirical context where it takes place, a case study was conducted and data was collected through semi-structured interviews to key informants involved in the process. A link between value-in-use dimensions emerged suggesting the importance to the logistic provider to adapt its operation and internal organization in order to better contribute to the value creation process. The mechanisms that influence the experience lived by the logistic provider’s customer were identified and point to the importance of interactions and building a strong relationship in order to create a trust and collaborative environment between companies.info:eu-repo/semantics/publishedVersio

Aplicação foliar de fertilizante organo mineral e soluções de ácido húmico em soja sob plantio direto.

O objetivo deste trabalho foi avaliar o efeito da aplicação foliar de produto à base de ácido húmico e da fração isolada sobre a produtividade de soja (Glycine max) em sistema de plantio direto no Cerrado.bitstream/CNPS-2010/14934/1/circtec35-2006-fertilizante.pd

First-order transition in small-world networks

The small-world transition is a first-order transition at zero density $p$ of shortcuts, whereby the normalized shortest-path distance undergoes a discontinuity in the thermodynamic limit. On finite systems the apparent transition is shifted by $\Delta p \sim L^{-d}$. Equivalently a ``persistence size'' $L^* \sim p^{-1/d}$ can be defined in connection with finite-size effects. Assuming $L^* \sim p^{-\tau}$, simple rescaling arguments imply that $\tau=1/d$. We confirm this result by extensive numerical simulation in one to four dimensions, and argue that $\tau=1/d$ implies that this transition is first-order.Comment: 4 pages, 3 figures, To appear in Europhysics Letter

Patterns of leprosy at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa, and review of current clinical practice

Background. The World Health Organization announced a strategy to eliminate childhood leprosy infections, visible deformities and discriminatory legislation against leprosy patients by 2020. However, challenges in achieving a leprosy-free world and preventing neurological sequelae still exist. HIV infection is a challenge in South Africa (SA). HIV-leprosy co-infection may result in an increase in the frequency of leprosy reactions without affecting the spectrum of leprosy. From 1921 to 1997, the prevalence of leprosy remained <1 patient per 10 000 population. Current SA literature has very scanty information regarding leprosy infections. Objectives. To describe the trend of new leprosy patients at Chris Hani Baragwanath Academic Hospital, Johannesburg, SA, from 1999 to 2015, including demographics, clinical spectrum and treatment outcomes. Methods. A retrospective review of patients’ clinical records was undertaken. Data on demographics, clinical spectrum including the leprosy classification, reactions, neurological involvement, association with HIV infection and treatment outcomes were extracted. Data analysis was performed using descriptive and inferential statistics and a time series analysis. Results. An upward trend from 1999 to 2001 was followed by a decline in the number of new patients. Eighty patients were registered over a period of 17 years, with a male-to-female ratio of 3:1. Thirty-six patients were immigrants, and 5 were children aged <15 years. Multibacillary leprosy was the most common type (n=71 patients). Thirty-six patients had the lepromatous leprosy subtype, 22 were borderline lepromatous, 13 were borderline tuberculoid, 6 were borderline borderline, and 3 had tuberculoid leprosy. Thirty-one patients presented with reactions, type 1 in 9 patients and type 2 in 21 patients, with both types in 1 patient. Grade 2 neurological deformities were diagnosed in 37 patients, of whom 2 were children. Eight patients were found to have HIV-leprosy co-infection. Of 52 patients who completed treatment, 26 were cured and 26 were lost to follow-up. Twenty-one patients defaulted from treatment, while 3 patients relapsed. Conclusions. This study highlights the current status of leprosy in a low-endemic centre with declining numbers of new patients. Multibacillary forms with grade 2 disabilities (G2Ds) are common. The constant emergence of leprosy in our population highlights shortfalls in our control campaigns. Furthermore, a high rate of G2Ds necessitates scrutiny of education directed at early patient detection and follow-up strategies