221 research outputs found

    Implications of sustainable agricultural intensification for family farming in Africa: anthropological perspectives

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    In this paper, we will explore the ways in which sustainable intensification interventions often overlook fundamental social dynamics in rural landscapes. We provide evidence of the underlying social, political and environmental contexts that affect farmers’ land-use decisions. While there are numerous initiatives to promote a Green Revolution for Africa, many tend to be dominated by technical fixes that fail to understand rural farmers’ condi - tions or aspirations and focus narrowly on increasing productivity. These technical solu - tions rarely address the broader social, economic and political challenges to agricultural production and farmers’ livelihoods. Finally, top-down technical approaches frequently fail to build on the local knowledge, innovative capacity and expertise of farmers and members of rural communities throughout Africa. Examples from fieldwork in Ghana, Ethiopia and Tanzania are used to illustrate our arguments

    Enhanced Potency of Bivalent Small Molecule gp41 Inhibitors

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    Low molecular weight peptidomimetic inhibitors with hydrophobic pocket binding properties and moderate fusion inhibitory activity against HIV-1 gp41-mediated cell fusion were elaborated by increasing the available surface area for interacting with the heptad repeat-1 (HR1) coiled coil on gp41. Two types of modifications were tested: 1) increasing the overall hydrophobicity of the molecules with an extension that could interact in the HR1 groove, and 2) forming symmetrical dimers with two peptidomimetic motifs that could potentially interact simultaneously in two hydrophobic pockets on the HR1 trimer. The latter approach was more successful, yielding 40–60 times improved potency against HIV fusion over the monomers. Biophysical characterization, including equilibrium binding studies by fluorescence and kinetic analysis by Surface Plasmon Resonance, revealed that inhibitor potency was better correlated to off-rates than to binding affinity. Binding and kinetic data could be fit to a model of bidentate interaction of dimers with the HR1 trimer as an explanation for the slow off-rate, albeit with minimal cooperativity due to the highly flexible ligand structures. The strong cooperativity observed in fusion inhibitory activity of the dimers implied accentuated potency due to the transient nature of the targeted intermediate. Optimization of monomer, dimer or higher order structures has the potential to lead to highly potent non-peptide fusion inhibitors by targeting multiple hydrophobic pockets

    ‘They think we are delaying their outputs’. The challenges of interdisciplinary research: understanding power dynamics between social and biophysical scientists in international crop breeding teams

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    Public sector crop improvement for development programmes aims to produce varieties tailored to the needs of smallholder farmers and their environments. Understanding how social heterogeneity, including gender, drives trait preferences is essential to ensure that crop improvement objectives meet farmers’ and stakeholder demands. This requires an interdisciplinary approach, integrating social science knowledge with crop breeding. Although the necessity of interdisciplinary research is recognised and promoted, it is impeded by a multitude of challenges including ontological and epistemological differences, institutional and global hierarchies, disciplinary power relations and struggles for scientific authority. The Agricultural Research for Development (AR4D) sector is marked by entrenched power differentials, including dominance of the biophysical sciences, a historical emphasis on technical solutions which ignores social contexts, and the underrepresentation of women scientists and farmers themselves. Nevertheless, there is limited theoretically informed analysis of power dynamics within AR4D settings. Drawing on qualitative, ethnographic observations of the Feed the Future Innovation Lab for Crop Improvement (ILCI), this article seeks to understand how power affects interdisciplinary research processes. Critical ethnography and power theory is used to analyse power within international crop breeding collaborations and the implications for inclusive knowledge production and research impact. The Powercube is used to examine how visible, hidden and invisible forms of power manifest within local, national, and international relationships across closed, invited and claimed spaces. Our findings suggest that these intersecting power dimensions, which include disciplinary, gendered, institutional and global hierarchies, constrain the contributions that individual researchers can make – particularly social scientists – thereby hindering disciplinary integration. The ILCI case study reveals the complex multi-dimensional dynamics that emerge within agricultural research teams and highlights structural limitations constraining efforts to build socially inclusive and gender-responsive crop improvement programmes. The article contributes to a small but growing literature studying the social construction of agricultural science, and provides insights that can enable interdisciplinary research strategies to more effectively meet the needs of farmers and other stakeholders

    Development of the NASA Digital Astronaut Project Muscle Model

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    This abstract describes development work performed on the NASA Digital Astronaut Project Muscle Model. Muscle atrophy is a known physiological response to exposure to a low gravity environment. The DAP muscle model computationally predicts the change in muscle structure and function vs. time in a reduced gravity environment. The spaceflight muscle model can then be used in biomechanical models of exercise countermeasures and spaceflight tasks to: 1) develop site specific bone loading input to the DAP bone adaptation model over the course of a mission; 2) predict astronaut performance of spaceflight tasks; 3) inform effectiveness of new exercise countermeasures concepts

    Theories of International Regimes

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    Over the last decade, international regimes have become a major focus of empirical research and theoretical debate within international relations. This article provides a critical review of this literature. We survey contending definitions of regimes and suggest dimensions along which regimes vary over time or across cases; these dimensions might be used to operationalize “regime change.” We then examine four approaches to regime analysis: structural, game-theoretic, functional, and cognitive. We conclude that the major shortcoming of the regimes literature is its failure to incorporate domestic politics adequately. We suggest a research program that begins with the central insights of the interdependence literature which have been ignored in the effort to construct “systemic” theory.Governmen

    Transport of Explosive Residue Surrogates in Saturated Porous Media

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    Department of Defense operational ranges may become contaminated by particles of explosives residues (ER) as a result of low-order detonations of munitions. The goal of this study was to determine the extent to which particles of ER could migrate through columns of sandy sediment, representing model aquifer materials. Transport experiments were conducted in saturated columns (2 × 20 cm) packed with different grain sizes of clean sand or glass beads. Fine particles (approximately 2 to 50 Όm) of 2,6-dinitrotoluene (DNT) were used as a surrogate for ER. DNT particles were applied to the top 1 cm of sand or beads in the columns, and the columns were subsequently leached with artificial groundwater solutions. DNT migration occurred as both dissolved and particulate phases. Concentration differences between unfiltered and filtered samples indicate that particulate DNT accounted for up to 41% of the mass recovered in effluent samples. Proportionally, more particulate than dissolved DNT was recovered in effluent solutions from columns with larger grain sizes, while total concentrations of DNT in effluent were inversely related to grain size. Of the total DNT mass applied to the uppermost layer of the column, <3% was recovered in the effluent with the bulk remaining in the top 2 cm of the column. Our results suggest there is some potential for subsurface migration of ER particles and that most of the particles will be retained over relatively short transport distances
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