937 research outputs found

    Addressing gender-based violence in the Sierra Leone conflict: Notes from the field

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    Sierra Leone’s transition has witnessed a number of landmark procedural and legal innovations which have had widespread implications for international gender justice. The 11-year conflict had shattered the country, leaving more than a million people displaced and thousands of women coping with the aftermath of sexual violence. Then, in 1999, the Lomé Peace Accord in 1999 traded amnesty for peace and made provision for the establishment of the Sierra Leone Truth Commission. The United Nations Security Council subsequently established a Special Court to prosecute those who bore ‘the greatest responsibility’ for atrocities committed during the conflict

    The Role of Cuticular Hydrocarbons in the Pre-mating Isolation of Two Pissodes Species

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    Pissodes strobi and P. nemorensis are weevils (Coleoptera, Curculionidae) that infest pines (Pinus spp.) and spruces (Picea spp.). Previous studies indicate that they are able to hybridize. In the spring, breeding site specificity maintains reproductive isolation, but in the late summer, both species occupy lateral branches of host trees. Aggregation pheromones for P. nemorensis have been identified but the mechanism for late summer isolation is unknown. Cuticular hydrocarbons have been shown to play a role in the chemical recognition of species, sex, kin, and caste in many groups of insects. The large number of possible compounds and the even larger numbers of possible combinations creates potential for much information to be encoded. Cuticular hydrocarbon samples from P. strobi were collected from an infestation in a white pine stand in Pompey, NY. The cuticular hydrocarbon samples were analyzed by coupled gas chromatography-mass spectrometry. Statistical analysis of the cuticular hydrocarbon profiles revealed a shift of the cuticular hydrocarbon profile between spring and summer males while the profile of the females remained constant between the two seasons. This shift in cuticular hydrocarbon profile may be indicative of a seasonal change that prevents P. strobi and P. nemorensis from interbreeding in the summer when the two species share the same habitat

    Differentiable but exact formulation of density-functional theory

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    The universal density functional F of density-functional theory is a complicated and ill-behaved function of the density—in particular, F is not differentiable, making many formal manipulations more complicated. While F has been well characterized in terms of convex analysis as forming a conjugate pair (E, F) with the ground-state energy E via the Hohenberg–Kohn and Lieb variation principles, F is nondifferentiable and subdifferentiable only on a small (but dense) subset of its domain. In this article, we apply a tool from convex analysis, Moreau–Yosida regularization, to construct, for any ε > 0, pairs of conjugate functionals (ε E, ε F) that converge to (E, F) pointwise everywhere as ε → 0+, and such that ε F is (Fréchet) differentiable. For technical reasons, we limit our attention to molecular electronic systems in a finite but large box. It is noteworthy that no information is lost in the Moreau–Yosida regularization: the physical ground-state energy E(v) is exactly recoverable from the regularized ground-state energy ε E(v) in a simple way. All concepts and results pertaining to the original (E, F) pair have direct counterparts in results for (ε E, ε F). The Moreau–Yosida regularization therefore allows for an exact, differentiable formulation of density-functional theory. In particular, taking advantage of the differentiability of ε F, a rigorous formulation of Kohn–Sham theory is presented that does not suffer from the noninteracting representability problem in standard Kohn–Sham theory

    Young children's cognitive achievement: home learning environment, language and ethnic background

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    For decades, research has shown differences in cognitive assessment scores between White and minority ethnic group(s) learners as well as differences across different minority ethnic groups. More recent data have indicated that the home learning environment and languages spoken can impact cognitive assessment and other corollary outcomes. This study uses the Millennium Cohort Study to jointly assess how minority ethnic group, home learning environment and home languages predict child cognitive assessment scores. Regression analyses were conducted using two assessment measures. The following is hypothesised: (1) cognitive achievement scores vary by minority ethnic group, (2) more home learning environment in early childhood leads to higher cognitive development scores and (3) English only in the home yields the highest cognitive scores while no English in the home yields the lowest. Findings reveal that there are differences in cognitive scores along ethnic group categories although there are also some unexpected findings. Home learning environment does not play as large a role as was predicted in raising the assessment scores overall for learners while speaking English in the home does, irrespective of ethnic background

    Reduced Leukocyte Infiltration in Absence of Eosinophils Correlates With Decreased Tissue Damage and Disease Susceptibility in ΔdblGATA Mice During Murine Neurocysticercosis

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    Neurocysticercosis (NCC) is one of the most common helminth parasitic diseases of the central nervous system (CNS) and the leading cause of acquired epilepsy worldwide. NCC is caused by the presence of the metacestode larvae of the tapeworm Taenia solium within brain tissues. NCC patients exhibit a long asymptomatic phase followed by a phase of symptoms including increased intra-cranial pressure and seizures. While the asymptomatic phase is attributed to the immunosuppressive capabilities of viable T. solium parasites, release of antigens by dying organisms induce strong immune responses and associated symptoms. Previous studies in T. solium-infected pigs have shown that the inflammatory response consists of various leukocyte populations including eosinophils, macrophages, and T cells among others. Because the role of eosinophils within the brain has not been investigated during NCC, we examined parasite burden, disease susceptibility and the composition of the inflammatory reaction in the brains of infected wild type (WT) and eosinophil-deficient mice (ΔdblGATA) using a murine model of NCC in which mice were infected intracranially with Mesocestoides corti, a cestode parasite related to T. solium. In WT mice, we observed a time-dependent induction of eosinophil recruitment in infected mice, contrasting with an overall reduced leukocyte infiltration in ΔdblGATA brains. Although, ΔdblGATA mice exhibited an increased parasite burden, reduced tissue damage and less disease susceptibility was observed when compared to infected WT mice. Cellular infiltrates in infected ΔdblGATA mice were comprised of more mast cells, and αβ T cells, which correlated with an abundant CD8+ T cell response and reduced CD4+ Th1 and Th2 responses. Thus, our data suggest that enhanced inflammatory response in WT mice appears detrimental and associates with increased disease susceptibility, despite the reduced parasite burden in the CNS. Overall reduced leukocyte infiltration due to absence of eosinophils correlates with attenuated tissue damage and longer survival of ΔdblGATA mice. Therefore, our study suggests that approaches to clear NCC will require strategies to tightly control the host immune response while eradicating the parasite with minimal damage to brain tissue

    Design of continuous circulation sub for gas drilling and the mechanical analysis on the sub body

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    AbstractGas drilling, as an important part of underbalanced drilling, can increase drilling speed. But in the process of conventional gas drilling, it tends to cause cutting settlement, borehole collapse, sticking and other safety hazards because gas circulation has to be interrupted. Therefore, this paper presents a continuous circulation sub which can be installed and removed easily. With this sub, gas circulation will not be interrupted when drilling tools are connected and removed. This sub is composed of body, main valve, bypass valve and side entry sub. The structure design of its key components (i.e. main and bypass valves) were fulfilled. Based on statics analysis on the sub body, its force situations under extension, torsion and internal pressure were simulated by using the ANSYS finite element analysis software. It is shown that its stress distribution trend is consistent with its elastic–plastic mechanics analysis results. Stress concentrates around the two round holes of the sub body, and the maximum deformation amount is still at the stage of elastic deformation. The analysis results are in line with the elastic–plastic mechanics analysis results, and the requirement of body strength is satisfied. This paper provides a new program to guarantee the drilling safety of extended-reach wells, underbalanced wells and narrow-density window wells
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