Random Primordial Magnetic Fields and the Gas Content of Dark Matter Halos

We recently predicted the existence of random primordial magnetic fields (RPMF) in the form of randomly oriented cells with dipole-like structure with a cell size $L_0$ and an average magnetic field $B_0$. Here we investigate models for primordial magnetic field with a similar web-like structure, and other geometries, differing perhaps in $L_0$ and $B_0$. The effect of RPMF on the formation of the first galaxies is investigated. The filtering mass, $M_F$, is the halo mass below which baryon accretion is severely depressed. We show that these RPMF could influence the formation of galaxies by altering the filtering mass and the baryon gas fraction of a halo, $f_g$. The effect is particularly strong in small galaxies. We find, for example, for a comoving B_0=0.1\muG, and a reionization epoch that starts at $z_s=11$ and ends at $z_e=8$, for $L_0=100\,\text{pc}$ at $z=12$, the $f_g$ becomes severely depressed for M<10^7\msun, whereas for $B_0=0$ the $f_g$ becomes severely depressed only for much smaller masses, M<10^5\msun. We suggest that the observation of $M_F$ and $f_g$ at high redshifts can give information on the intensity and structure of primordial magnetic fields.Comment: 7 pages, 10 figures, accepted for publication in MNRAS (several improvements after suggestions of the referee

JEGUATÁ: O CAMINHAR ENTRE OS GUARANI

In this article the guarani ‘walk’ is elected as reflection’s object as from ethnographical frequentation in some spaces where mbyá and nhandeva groups can be actually found and circulating in eastern Rio Grande do Sul. As a specific form of mobility based on differentiated lecture of the elements in space, jeguatá or just guatá, (walk in the guarani idiom) will be here analyzed in interface with shamanism, as a cosmopolitical form through whichspaces are understood, forefront the presence and absence, and consequently alterity’s influence as identified by these groups.RESUMO: Neste artigo o ‘caminhar’ guarani é eleito como objeto de reflexões a partir da freqüentação etnográfica de alguns espaços onde se encontram e circulam atualmente grupos mbyá e nhandeva na região leste do Rio Grande do Sul. Enquanto forma de mobilidadeespecífica pautada por leituras diferenciadas dos elementos do espaço, o jeguatá ou somente guatá (caminhar no idioma guarani) será aqui analisado em sua interface com o xamanismo, enquanto forma de cosmopolítica através da qual os espaços são entendidos, frente à presença e ausência, e conseqüente influência, das alteridades identificadas por estes grupos

Evaluation of sampling techniques and influence of environmental variables on ants in forest fragments in an oil extraction area in the Amazon

Around the world, urban landscapes are environments modified by man, generally related to low diversity. The efficiency of a biodiversity inventory is linked to the choice of the sampling technique since the taxonomic and ecological responses of the taxons vary between methods. Here we investigate differences in the ant’s composition sampled using three different techniques in two fragments of the urban forest in the Brazilian Amazon. We also assessed whether the different techniques maintained the same ecological responses. We sampled 12 collection points at each fragment, at vegetation, and manual collection and Winkler extractor on the ground. At the same points, soil samples were collected to determine their granulometry, pH, and concentrations of organic matter, sodium, phosphorus, and potassium. We collected 115 taxa and 4720 ants. The Cururu was the richest site with more species in general, as well as in the techniques of manual collection and Winkler. We detected a complementary effect on sampling techniques, which collected different ants’ assemblages. The potassium concentration positively influenced the assemblage’s composition, but its effect varies according to the sampling techniques used. The studied fragments revealed diversity very similar to those registered in continuous Amazonian forests. The use of sampling techniques together improves the representation of the diversity of ants in the studied fragments. Edaphic environmental variables seem to have a predominant effect on ants, affecting their distribution in the landscape even in urban fragments. This highlights the importance of urban forest fragments and their inherent ecological processes

Devotion and resistance: the tactics of the Folia de Reis Hosts in the metropolitan region of the State of Rio de Janeiro

As Folias de Reis realizam circuitos de visitações às casas dos devotos em um período conhecido como giros ou jornadas, ocorrendo nas madrugadas dos fins de semana entre os dias 24 de dezembro e 6 de janeiro, dia dos Santos Reis. Para elaborar um estudo etnográfico que abarque a complexidade desse empreendimento devocional, divido este artigo em três partes: a primeira visa discutir quem são os devotos da Folia de Reis e seus papéis na execução da devoção; a segunda parte explora a ocupação dos espaços da casa e da rua no momento da realização dos giros da folia; e a parte final pauta-se na exploração das “táticas” (Certeau, 1994) praticadas pelos devotos anfitriões da bandeira para a garantia da integridade física e moral dos foliões e seus familiares durante o circuito ritual realizado na periferia da Região Metropolitana do Estado do Rio de Janeiro.The Folias de Reis organize visits to the homes of the devotees in a period known as giros or journeys, taking place at dawn on weekends between December 24 and January 6, the day of the Santos Reis. In order to carry out an ethnographic study that encompasses the complexity of this devotional endeavor, this article is divided into three parts: a first part that discusses who are the devotees of the Folia de Reis and their roles in the execution of devotion, a second part explores the availability of the spaces of home and street at the time of the revelry tours, and the final part of exploring the “tactics” (CERTEAU, 1994) practiced by the devout hosts of the flag to guarantee the physical and moral integrity of the revelers and their families during the ritual circuit carried out on the periphery of the Metropolitan Region of the State of Rio de Janeiro

Entre o Planejamento Estratégico Formal e Informal: um Estudo de Caso Exploratório sobre a Prática de Estratégia nas Organizações

Most studies on strategy formation have a constitutive contingency element that defines variables through which one could sort organizations into a certain order to indicate what type of strategy formation is more suitable for each (e.g. Mintzberg & McHugh, 1985). This almost prescriptive ordinance concerning the content, process and practice of strategy in organizations can lead one to the perception that it is possible to determine the pattern of strategy of formation in organizations through the simple analysis of some predetermined variables. Guided by the strategy-as-practice approach (Jarzabkowski, 2005, 2008; Whittington, 1996, 2006), this paper explores the practice of strategic planning based on an exploratory single case study in a project-based organization, through which it was possible to identify change processes that shaped different stages of the strategic planning practice over the years with distinct characteristics regarding its (in)formality. These processes were analyzed using an approach inspired on the structuration theory (Giddens, 1984), indicating that the adequate level of strategic planning formalization should be defined by the structuration of practice in its social dynamic