Mapping Public Relations in Europe: Writing National Histories against the US Paradigm

The purpose of this paper is to recall the early historical development of public relations (PR) in five European countries so as to trace the emergence of the study and teaching of PR as a profession in Europe as compared to the United States. In light of recent accounts of the history of PR, the main goal of this study is to contribute to a comparative, international historical narrative by providing an overview of the main events that shaped the early stages of the profession in the United Kingdom, Italy, France, Germany and Spai

Evolving wormhole geometries within nonlinear electrodynamics

In this work, we explore the possibility of evolving (2+1) and (3+1)-dimensional wormhole spacetimes, conformally related to the respective static geometries, within the context of nonlinear electrodynamics. For the (3+1)-dimensional spacetime, it is found that the Einstein field equation imposes a contracting wormhole solution and the obedience of the weak energy condition. Nevertheless, in the presence of an electric field, the latter presents a singularity at the throat, however, for a pure magnetic field the solution is regular. For the (2+1)-dimensional case, it is also found that the physical fields are singular at the throat. Thus, taking into account the principle of finiteness, which states that a satisfactory theory should avoid physical quantities becoming infinite, one may rule out evolving (3+1)-dimensional wormhole solutions, in the presence of an electric field, and the (2+1)-dimensional case coupled to nonlinear electrodynamics.Comment: 17 pages, 1 figure; to appear in Classical and Quantum Gravity. V2: minor corrections, including a referenc

The development of public relations in dictatorships - Southern and Eastern European perspectives from 1945 to 1990

The progressive version of public relations history present it as a by-product of pluralist political systems or a democratic dividend. It has been claimed that public relations thrives within open media systems and market economies but struggles in highly controlled governmental systems (dictatorships, juntas, and closed economies). This paper considers how political history and political systems affected the formation of public relations practices in regions of Europe that, after 1945, were under military dictatorships (Spain and Portugal), a military junta (Greece) and were contained in the Soviet bloc. Using comparative history methodology, the notion that public relations operates solely in democracies is challenged, although it is conceded that practice thrived in post-war Western Europe but struggled to develop in parts of southern and eastern Europe

Traversable wormholes coupled to nonlinear electrodynamics

In this work we explore the possible existence of static, spherically symmetric and stationary, axisymmetric traversable wormholes coupled to nonlinear electrodynamics. Considering static and spherically symmetric (2+1) and (3+1)-dimensional wormhole spacetimes, we verify the presence of an event horizon and the non-violation of the null energy condition at the throat. For the former spacetime, the principle of finiteness is imposed, in order to obtain regular physical fields at the throat. Next, we analyze the (2+1)-dimensional stationary and axisymmetric wormhole, and also verify the presence of an event horizon, rendering the geometry non-traversable. Relatively to the (3+1)-dimensional stationary and axisymmetric wormhole geometry, we find that the field equations impose specific conditions that are incompatible with the properties of wormholes. Thus, we prove the non-existence of the general class of traversable wormhole solutions, outlined above, within the context of nonlinear electrodynamics.Comment: 9 pages, Revtex4. V2: major change in title; considerable additions in the Introduction and in the rotating solution, no physics changes; correction of a reference, one reference added; now 10 pages. This version to appear in Classical and Quantum Gravit

Entomological characterization of malaria in northern Colombia through vector and parasite species identification, and analyses of spatial distribution and infection rates

Background: Malaria remains a worldwide public health concern and, in Colombia, despite the efforts to stop malaria transmission, the incidence of cases has increased over the last few years. In this context, it is necessary to evaluate vector diversity, infection rates, and spatial distribution, to better understand disease transmission dynamics. This information may contribute to the planning and development of vector control strategies. Results: A total of 778 Anopheles mosquitoes were collected in fifteen localities of Córdoba from August 2015 to October 2016. Six species were identified and overall, Anopheles albimanus was the most widespread and abundant species (83%). Other species of the Nyssorhynchus subgenus were collected, including Anopheles triannulatus (13%), Anopheles nuneztovari (1%), Anopheles argyritarsis (< 1%) and two species belonging to the Anopheles subgenus: Anopheles pseudopunctipennis (3%) and Anopheles neomaculipalpus (< 1%). Four species were found naturally infected with two Plasmodium species: Anopheles nuneztovari was detected naturally infected with Plasmodium falciparum and Anopheles pseudopunctipennis with Plasmodium vivax, whereas An. albimanus and An. triannulatus were found infected with both parasite species and confirmed by nested PCR. Conclusions: In general, the obtained results were contrasting with previous studies in terms of the most abundant and widespread collected species, and regarding infection rates, which were higher than those previously reported. A positive relationship between mosquito local abundance at the locality level and human infection at the municipality level was found. Mosquito local abundance and the number of houses with mosquitoes in each village are factors explaining malaria human cases in these villages. The obtained results suggest that other factors related to the apparent variation in malaria eco-epidemiology in northern Colombia, must be identified, to provide health authorities with better decision tools aiming to design control and prevention strategies

Exact solutions of f(R) gravity coupled to nonlinear electrodynamics

In this work, exact solutions of static and spherically symmetric space-times are analyzed in f(R) modified theories of gravity coupled to nonlinear electrodynamics. Firstly, we restrict the metric fields to one degree of freedom, considering the specific case of g_tt\g_rr = -1. Using the dual P formalism of nonlinear electrodynamics an exact general solution is deduced in terms of the structural function H_P. In particular, specific exact solutions to the gravitational field equations are found, confirming previous results and new pure electric field solutions are found. Secondly, motivated by the existence of regular electric fields at the center, and allowing for the case of g_tt\g_rr \= -1, new specific solutions are found. Finally, we outline alternative approaches by considering the specific case of constant curvature, followed by the analysis of a specific form for f(R).Comment: 14 pages, 6 figures, revtex4; minor changes & details added, conclusions remain; accepted for publication in Phys. Rev.

Spatial Clustering of Dark Matter Halos: Secondary Bias, Neighbor Bias, and the Influence of Massive Neighbors on Halo Properties

We explore the phenomenon commonly known as halo assembly bias, whereby dark matter halos of the same mass are found to be more or less clustered when a second halo property is considered, for halos in the mass range $3.7 \times 10^{11} \; h^{-1} \mathrm{M_{\odot}} - 5.0 \times 10^{13} \; h^{-1} \mathrm{M_{\odot}}$. Using the Large Suite of Dark Matter Simulations (LasDamas) we consider nine commonly used halo properties and find that a clustering bias exists if halos are binned by mass or by any other halo property. This secondary bias implies that no single halo property encompasses all the spatial clustering information of the halo population. The mean values of some halo properties depend on their halo's distance to a more massive neighbor. Halo samples selected by having high values of one of these properties therefore inherit a neighbor bias such that they are much more likely to be close to a much more massive neighbor. This neighbor bias largely accounts for the secondary bias seen in halos binned by mass and split by concentration or age. However, halos binned by other mass-like properties still show a secondary bias even when the neighbor bias is removed. The secondary bias of halos selected by their spin behaves differently than that for other halo properties, suggesting that the origin of the spin bias is different than of other secondary biases.Comment: 14 pages, LaTeX; minor revisions, and added references; results unchange