879 resultados para Black Holes
Resumo:
This article explores the ways in which transnational feminist analysis can be deployed to reconfigure new gendered and racialized cartographies of the African Diaspora in Europe. First, I position contemporary film representations of trafficked Nigerian sex workers in Italy in dialogical relation to 19th century discourses of black sexuality - in particular, Sharpley-Whiting's (1999) reinscribed 'Black Venus Master Narrative' - and assess historical and geographical (dis)continuities in their modes of signification. Second, by linking endemic factors feeding the supply of Nigerian women for the purposes of (in)voluntary participation in the Italian sex industry, such as the localized feminization of poverty and regionally specific perceptions of sex work as a temporary economic strategy, I engage with broader feminist debates on victimization and agency in global sex work and migration literatures. In doing so, this dialectical think piece highlights the gendered complexities of new African diasporic formations and the ways in which their growth is facilitated by broader illegal networks that shape and are shaped by vicissitudes in glocalized economies. © 2004 Elsevier Ltd. All rights reserved.
Resumo:
Drawing on local criminal court records in western and central South Carolina, this dissertation follows the legal experiences of black girls in South Carolina courts between 1885 and 1920, a time span that includes the aftermath of Reconstruction and the foundational years of Jim Crow. While scholars continue to debate the degree to which black children were included in evolving conversations about childhood and child protection, this dissertation argues that black girls were critical to turn-of-the century debates about all children's roles in society. Far from invisible in the courts and jails of their time, black girls found themselves in the crosshairs of varying forms of power --including intraracial community surveillance, burgeoning local government, Progressive reform initiatives and military policy -- particularly when it came to matters of sexuality and reproduction. Their presence in South Carolina courts established boundaries between early childhood, adolescence and womanhood and pushed legal stakeholders to consider the legal implication of age, race, and gender in criminal proceedings. Age had a complicated effect on black girls' legal encounters; very young black girls were often able to claim youth and escape harsher punishments, while courts often used judicial discretion to levy heavier sentences to adolescents and violent girl offenders. While courts helped to separate early childhood from the middle years, they also provided a space for African-American children and family to engage a legal system that was moving rapidly toward disenfranchising blacks.
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This paper discusses preconditioned Krylov subspace methods for solving large scale linear systems that originate from oil reservoir numerical simulations. Two types of preconditioners, one being based on an incomplete LU decomposition and the other being based on iterative algorithms, are used together in a combination strategy in order to achieve an adaptive and efficient preconditioner. Numerical tests show that different Krylov subspace methods combining with appropriate preconditioners are able to achieve optimal performance.
Resumo:
A parallel time-domain algorithm is described for the time-dependent nonlinear Black-Scholes equation, which may be used to build financial analysis tools to help traders making rapid and systematic evaluation of buy/sell contracts. The algorithm is particularly suitable for problems that do not require fine details at each intermediate time step, and hence the method applies well for the present problem.
Resumo:
Spatiotemporal variation in seabird demographic parameters is often pronounced and may be an important source of information on the state of marine ecosystems. Black-legged kittiwakes Rissa tridactyla in Britain and Ireland show strong regional structure in breeding productivity, and both temporal and spatial variation are probably related to abundance of the principal prey of breeding kittiwakes, the lesser sandeel Ammodytes marinus. Annual regional estimates of sandeel abundance do not exist, prohibiting direct tests of this hypothesis. We examined relationships between kittiwake breeding productivity and 2 potential proxies of sandeel abundance, winter sea surface temperature (SST) and abundance of Calanus copepods, within and among 6 regions in Britain and Ireland from 1986 to 2004. Means and trends in winter SST differed among regions, with higher means and less pronounced increasing trends in western (Atlantic) regions than in eastern (North Sea) regions. A negative relationship between breeding productivity and winter SST in the previous year was found within 2 regions (East Scotland and Orkney), as well as in a cross-regional analysis. Results were inconclusive for Calanus abundance, with a positive relationship in East Scotland and negative in Orkney. These results demonstrate that although a single environmental driver (SST) is related to both within- and between-region variation in a key demographic parameter, regional heterogeneity in SST trends as well as the importance of other factors may lead to highly variable responses. Understanding this heterogeneity is critical for predicting long-term effects of climate change or other anthropogenic drivers on marine ecosystems.
Resumo:
During recent decades anthropogenic activities have dramatically impacted the Black Sea ecosystem. High levels of riverine nutrient input during the 1970s and 1980s caused eutrophic conditions including intense algal blooms resulting in hypoxia and the subsequent collapse of benthic habitats on the northwestern shelf. Intense fishing pressure also depleted stocks of many apex predators, contributing to an increase in planktivorous fish that are now the focus of fishing efforts. Additionally, the Black Sea's ecosystem changed even further with the introduction of exotic species. Economic collapse of the surrounding socialist republics in the early 1990s resulted in decreased nutrient loading which has allowed the Black Sea ecosystem to start to recover, but under rapidly changing economic and political conditions, future recovery is uncertain. In this study we use a multidisciplinary approach to integrate information from socio-economic and ecological systems to model the effects of future development scenarios on the marine environment of the northwestern Black Sea shelf. The Driver–Pressure–State-Impact-Response framework was used to construct conceptual models, explicitly mapping impacts of socio-economic Drivers on the marine ecosystem. Bayesian belief networks (BBNs), a stochastic modelling technique, were used to quantify these causal relationships, operationalise models and assess the effects of alternative development paths on the Black Sea ecosystem. BBNs use probabilistic dependencies as a common metric, allowing the integration of quantitative and qualitative information. Under the Baseline Scenario, recovery of the Black Sea appears tenuous as the exploitation of environmental resources (agriculture, fishing and shipping) increases with continued economic development of post-Soviet countries. This results in the loss of wetlands through drainage and reclamation. Water transparency decreases as phytoplankton bloom and this deterioration in water quality leads to the degradation of coastal plant communities (Cystoseira, seagrass) and also Phyllophora habitat on the shelf. Decomposition of benthic plants results in hypoxia killing flora and fauna associated with these habitats. Ecological pressure from these factors along with constant levels of fishing activity results in target stocks remaining depleted. Of the four Alternative Scenarios, two show improvements on the Baseline ecosystem condition, with improved waste water treatment and reduced fishing pressure, while the other two show a worsening, due to increased natural resource exploitation leading to rapid reversal of any recent ecosystem recovery. From this we conclude that variations in economic policy have significant consequences for the health of the Black Sea, and ecosystem recovery is directly linked to social–economic choices.