311 research outputs found
Engineered expression of the invertebrateâspecific scorpion toxin AaHIT reduces adult longevity and female fecundity in the diamondback moth Plutella xylostella
Background: Previous Genetic Pest Management (GPM) systems in diamondback moth (DBM) have relied on expressing lethal proteins (âeffectorsâ) that are âcellâautonomousâ i.e. do not leave the cell they are expressed in. To increase the flexibility of future GPM systems in DBM, we aimed to assess the use of a non cellâautonomous, invertebrateâspecific, neurotoxic effector â the scorpion toxin AaHIT. This AaHIT effector was designed to be secreted by expressing cells, potentially leading to effects on distant cells, specifically neuromuscular junctions. Results: Expression of AaHIT caused a âshaking/quiveringâ phenotype which could be repressed by provision of an antidote (tetracycline); a phenotype consistent with the AaHIT modeâofâaction. This effect was more pronounced when AaHIT expression was driven by the Hr5/ie1 promoter (82.44% of males, 65.14% of females) rather than Op/ie2 (57.35% of males, 48.39% of females). Contrary to expectations, the shaking phenotype and observed fitness costs were limited to adults where they caused severe reductions in mean longevity (â81%) and median female fecundity (â93%). qPCR of AaHIT expression patterns and analysis of piggyBacâmediated transgene insertion sites suggest that restriction of observed effects to the adult stages may be due to influence of local genomic environment on the tetOâAaHIT transgene. Conclusion: We have demonstrated the feasibility of using non cellâautonomous effectors within a GPM context for the first time in the Lepidoptera, one of the most economically damaging orders of insects. These findings provide a framework for extending this system to other pest Lepidoptera and to other secreted effectors
Measuring student attitude and knowledge in technology-rich biology classrooms
The use of technology in schools is now ubiquitous, but the effectiveness on the learning environment has mixed results. This paper describes the development and validation of an instrument to measure studentsâ attitudes toward and knowledge of technology with the aim of investigating any differences based on gender after a course where the science department made use of technology as an integral part of teaching biology. In this study, conducted in one school in the state of New York, in the United States of America, the Studentsâ Attitudes Toward and Knowledge of Technology Questionnaire was administered to nearly 700 high school science students. A principal component and principal factor analysis resulted in new scales from the validation of the instrument that demonstrated high reliabilities. There were statistically significant gender differences in all the scales of the questionnaire in favor of males
Understanding the political motivations that shape Rwandaâs emergent developmental state
Twenty years after its horrific genocide, Rwanda has become a model for economic development. At the same time, its government has been criticized for its authoritarian tactics and use of violence. Missing from the often-polarized debate are the connections between these two perspectives. Synthesizing existing literature on Rwanda in light of a combined year of fieldwork, we argue that the GoR is using the developmental infrastructure to deepen state power and expand political control. We first identify the historical pressures that have motivated the Rwanda Patriotic Front (RPF) to re-imagine the political landscape. Sectarian unrest, political rivalry, wider regional insecurity, and aid withdrawal have all pressured the RPF to identify growth as strategic. However, the countryâs political transformation extends beyond a prioritisation of growth and encompasses the reordering of the social and physical layout of the territory, the articulation of new ideologies and mindsets, and the provision of social services and surveillance infrastructure. Growth and social control go hand in hand. As such, the paperâs main contribution is to bring together the two sides of the Rwandan debate and place the country in a broader sociological literature about the parallel development of capitalist relations and transformations in state power
Financial Characteristics of Companies Audited by Large Audit Firms
Purpose â The purpose of this paper is to examine how financial characteristics associated with the choice of a big audit firm with further investigation on the agency costs of free cash flows.Design/methodology/approach â The sample used for this work includes industrial listed companies from Germany and France. To test our hypothesis, we used a number of logit models, extending the standard model selection audit firm, to include the variables of interest. Following previous work, our dependent dummy variable is Big4 or non-Big4.Findings â We observed that most independent variables in the German companies show similar results to previous work, but we did not have the same results for the French industry. Moreover, our findings suggest that the total debt and dividends can be an important reason for determining the choice of a large audit firm, reducing agency costs of free cash flows.Research limitations/implications â This study has some limitations on the measurements of the cost of the audit fees and also generates opportunities for additional searching.Originality/value â The paper provides only one aspect to explain the relationship between the problems of agency costs of free cash flow and influence in choosing a large auditing firm, which stems from investors\u27 demand for higher quality audits
Civil society leadership in the struggle for AIDS treatment in South Africa and Uganda
Includes abstract.Includes bibliographical references.This thesis is an attempt to theorise and operationalise empirically the notion of âcivil society leadershipâ in Sub-Saharan Africa. âAIDS leadership,â which is associated with the intergovernmental institutions charged with coordinating the global response to HIV/AIDS, is both under-theorised and highly context-specific. In this study I therefore opt for an inclusive framework that draws on a range of approaches, including the literature on âleadershipâ, institutions, social movements and the ânetworkâ perspective on civil society mobilisation. This framework is employed in rich and detailed empirical descriptions (âthick descriptionâ) of civil society mobilisation around AIDS, including contentious AIDS activism, in the key case studies of South Africa and Uganda. South Africa and Uganda are widely considered key examples of poor and good leadership (from national political leaders) respectively, while the Treatment Action Campaign (TAC) and The AIDS Support Organisation (TASO) are both seen as highly effective civil society movements. These descriptions emphasise âtransnational networks of influenceâ in which civil society leaders participated (and at times actively constructed) in order to mobilise both symbolic and material resources aimed at exerting influence at the transnational, national and local levels
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