Testing for Satisfiability in Modal Logics using a Subset-matching Size-bounded Cache

this paper we present a data type ---that we call "bit matrix"--- for caching the (in)consistency of sets of formulas. Bit matrices have three distinguishing features: (i) they can be queried for subsets and supersets; (ii) they can be bounded in size; and (iii) if bounded, they can easily implement different policies to resolve which results have to be kept. We have implemented caching mechanisms based on bit matrices and hash tables in *sat. In *sat, the bit matrix cache is bounded, and keeps the latest obtained (in)consistency results. We experiment with the benchmarks proposed for modal logic K at the "TABLEAUX Non Classical Systems Comparison (TANCS) 2000". On the basis of the results, we conclude that *sat performances are improved by (i) caching the result of intermediate consistency checks, (ii) using bit matrices instead of hash tables, and (iii) storing a small number of results in the bit matrice

Two Minute Brother: Contestation Through Gender, 'Race' and Sexuality

This article shows how a group of American Black female musicians are rapping themselves into existence against the powerless positions (both economic and cultural) that are offered to them. They ‘talk back talk Black’ (bell hooks, [sic] 1984) to colonialism. Firstly, they ridicule and undermine the strutting, bragging form of masculinity that wants to keep women firmly located as sexual objects. This article shows how this form of Black masculinity is itself a product of Black male cultural resistance to the racist myths that were used to legitimate slavery. Nevertheless, it operates to control and contain women and the expression of their sexuality. Secondly, the female rappers ‘defiantly speak’ to the traditional feminine discourses of maternalism, and its accompanying duties and obligations. Unlike many Black women who are able to use motherhood and the family to resist racism, these female rappers locate themselves firmly against tradition. They use rap music as the form in which to voice these challenges, investing the explicit sexual language of rap with new meanings. They use a ‘demand’ discourse to celebrate female sexuality and autonomy, articulating what is a usually perniciously silenced sexuality. Drawing upon a long tradition in Black female music (see Carby, 1986) the female rappers turn themselves from sexual objects into sexual subjects. In so doing they challenge the basis of the social order which seeks to contain them

A role for angiogenesis in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic debilitating disease characterized by distinct autoimmune, inflammatory and fibrovascular components which lead to synovial proliferation and joint destruction. However, existing treatments specifically target only autoimmune and inflammatory components despite the fact that neovascularization of the inflamed synovium is a hallmark of rheumatoid arthritis. Angiogenesis may contribute to synovial growth, leukocyte recruitment and tissue remodeling, thus potentiating disease progression. Although no therapies currently target angiogenesis, several existing therapies have anti-angiogenic activity. Recent advances in anti-angiogenic strategies in oncology, including the identification of integrin <FONT FACE="Symbol">a</font>vß3 as a crucial effector of angiogenesis, suggest a means to assess the role of angiogenesis in rheumatoid arthritis. Synovial endothelial cells have been shown to express integrin <FONT FACE="Symbol">a</font>vß3, suggesting that these cells may be targeted for angiogenesis inhibition. Prior studies in rat arthritis models have shown benefit after the addition of broad spectrum integrin antagonists. However, formal assessment of integrin-targeted anti-angiogenic activity is now underway. These controlled studies will be important in assessing the efficacy of therapies which target angiogenesis in RA

Virus genomes reveal factors that spread and sustained the Ebola epidemic

The 2013-2016 West African epidemic caused by the Ebola virus was of unprecedented magnitude, duration and impact. Here we reconstruct the dispersal, proliferation and decline of Ebola virus throughout the region by analysing 1,610 Ebola virus genomes, which represent over 5% of the known cases. We test the association of geography, climate and demography with viral movement among administrative regions, inferring a classic 'gravity' model, with intense dispersal between larger and closer populations. Despite attenuation of international dispersal after border closures, cross-border transmission had already sown the seeds for an international epidemic, rendering these measures ineffective at curbing the epidemic. We address why the epidemic did not spread into neighbouring countries, showing that these countries were susceptible to substantial outbreaks but at lower risk of introductions. Finally, we reveal that this large epidemic was a heterogeneous and spatially dissociated collection of transmission clusters of varying size, duration and connectivity. These insights will help to inform interventions in future epidemics