Standard map in magnetized relativistic systems: fixed points and regular acceleration

We investigate the concept of a standard map for the interaction of relativistic particles and electrostatic waves of arbitrary amplitudes, under the action of external magnetic fields. The map is adequate for physical settings where waves and particles interact impulsively, and allows for a series of analytical result to be exactly obtained. Unlike the traditional form of the standard map, the present map is nonlinear in the wave amplitude and displays a series of peculiar properties. Among these properties we discuss the relation involving fixed points of the maps and accelerator regimes.Comment: Work to appear in Phys. Rev. E. 2 figure

Plano de gestão para a Embrapa Meio-Norte.

bitstream/item/97671/1/DOC910001.pd

Leucena: alternativa forrageira de alta qualidade para caprinos e ovinos.

bitstream/item/53179/1/Folder-Leucena.pf.pd

Networks, [Mis]trust, and Pentecostal Conversion: narratives of divergent pathways among small Black entrepreneurs in Tshwane

This thesis is an exploration of the cultural meanings, practices, and discourse that impinge upon the workings of social capital and trust among small black entrepreneurs. Entrepreneurs need to draw on social networks to get advice and resources to launch and manage a business. The contacts that lead to successful outcomes are their social capital and they are a key component of entrepreneurial networks. Structural economic sociologists tend to emphasise 'structural holes', whereby a social actor who is in a position to bridge two actors with no direct ties to each other can parlay control over information into strategic advantage. Recent sociological literature highlights questions of meaning in networks and brings to the fore concerns with the larger cultural framework within which social networks are embedded. Relational economic sociologists contend that networks can be understood as composed of culturally constituted processes. Studies on the networks of South African entrepreneurs are few and far between, and they seem to suggest that African entrepreneurs don't mobilise social capital as well as their Indian and white counterparts. The research used qualitative approaches, relying on a combination of in-depth open-ended unstructured interviews and prolonged ethnographic immersion which generated rich understandings of entrepreneurs' lived experiences, subjective meanings, and contexts. The findings underscore the cultural contingency of social ties and network structure, suggesting that an entrepreneur's proneness to join particular types of associations and networks, and their ability to generate particular types of social ties and generalised trust has something to do with a range of cultural contingencies. The research devoted special attention to the cultural contingency of religion, bringing to light the entrepreneurial consequences of Pentecostal conversion. These intersect with, and extend far beyond, the networks of small black entrepreneurs, affecting issues at the very heart of entrepreneurship such as risk taking and proactiveness. I borrow the concept of 'cultural holes' to illustrate the contingencies of meaning that shape the networks and the entrepreneurial orientation of small black entrepreneurs and, ultimately, drive their divergent entrepreneurial trajectories. Finally, the study adumbrates a typology of small black entrepreneurs, arguing for the possibility that multiple cultural contingencies may open up alternate understandings of entrepreneurship

Guia politicamente incorreto da história do Brasil.

Os problemas envolvidos na classificação e na padronização da vida social têm sido alvo de minhas preocupações de estudo há quase uma década. De fato, venho escrevendo um livro sobre esse assunto. Nele, a classificação e a padronização são discutidas dentro de contextos interativos que ressaltam suas características de automatismo, de hábito, de reprodução de valores e de comportamento. Classificar é seguir uma regra adrede preparada no intuito de oferecer coerência a um corpo de ideias, buscando fortalecê‑lo. Para se ter um breve exemplo da importância e das implicações da classificação na vida social, basta lembrar alguns acontecimentos dos séculos 17 e 18 com relação aos estudos dos naturalistas. Sabe-se que, naquele período, a dominação europeia sobre a América carecia de uma teoria científica (classificatória) que desse fundamentos lógicos e empíricos à supremacia europeia pela inevitável ?demonstração? da inferioridade do Novo Mundo. Toda a diversa paisagem natural da América foi alvo desse veículo classificatório: seu ar, seu clima, seus pântanos, seus habitantes, seus animais, sua vegetação, suas terras, suas montanhas, seus vulcões.Obra resenhada: NARLOCH, Leandro. Guia politicamente incorreto da história do Brasil. São Paulo: Leya, 2009. 319 p