During 2004 to 2008, weed surveys were conducted in 373 wheat fields of two different cropped areas (southwest [SW] and southeast [SE]) of the southern region of Buenos Aires Province of Argentina where different weed communities were expected because of changes in cropping practices over time, including tillage, crop sequence, fertilizers, and herbicides applied. Weed communities differed between regions, with greater numbers of native species for the SW. Weed community diversity was also greater for the SW region, probably due to the more diverse land use that resulted in greater landscape heterogeneity. Rush skeletonweed, sand rocket, yellow starthistle and turnipseed occurred at higher constancy (proportion of fields in which a given species is present) in the SW region, whereas common chickweed, false bishop's weed, corn speedwell, and common lambsquarters were present more frequently in the SE region. Compared with the 1982 survey, constancy of weeds increased, but those species with high constancy in 1982 were also with high constancy in the recent surveys. Diversity (species richness) was greater in conventional than in a no-tillage system. The constancy of Italian ryegrass, sand rocket, and yellow starthistle was lower under no-till than conventional tillage. Surveys allow identification of changes in weed community related to different agricultural systems. Rotation of crops and livestock avoid the homogenization of the environment at the landscape level. Management strategies will be necessary to prevent the increase of weeds populations' size, preserving plant diversity and the properties of the agroecosystem.
Civil society actors contested the fifty-year long transition to a global economy based on the principles of neoliberalism. Mobilization against neoliberal measures represents one of the most common forms of social-movement activity across the world. We explore the evolution of resistance to economic liberalization from the 1970s to the current period. Our study highlights several dimensions of civic opposition to the implementation of free market policies, including: forms of neoliberalism; geographic distribution of protest events across world regions and time; and outcomes of movement campaigns.
Economic globalization in Latin America over the past four decades has resulted in some of the largest mass mobilizations in the region and has influenced electoral outcomes. This chapter traces the evolution of economic liberalization over time from the early years of the debt crisis to the institutionalization of neoliberalism as the dominant development strategy. Different forms of collective resistance to market-driven globalization are examined at the local, national, and transnational levels of social and political life. The authors also explore the current stage of globalization, characterized by intensifying environmental threats of resource extraction and climate change that are generating new rounds of popular mobilization. This overview concludes with a theoretical discussion of the key conditions driving the emergence of defensive mobilization in response to neoliberalism, including resource infrastructures, oppositional political parties, strategic experience, and the construction of meaning, grievances, and economic threats.
Se estudia la teoría clásica del electromagnetismo como una teoría gauge con grupo de simetría U(1).
Así mismo, se describe una teoría de discretización del cálculo para poder obtener resultados numéricos.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.