448 research outputs found

    Judicial Sales

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    Jellyfish and Fish Solve the Challenges of Turning Dynamics Similarly to Achieve High Maneuverability

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    Turning maneuvers by aquatic animals are essential for fundamental life functions such as finding food or mates while avoiding predation. However, turning requires resolution of a fundamental dilemma based in rotational mechanics: the force powering a turn (torque) is favored by an expanded body configuration that maximizes lever arm length, yet minimizing the resistance to a turn (the moment of inertia) is favored by a contracted body configuration. How do animals balance these opposing demands? Here, we directly measure instantaneous forces along the bodies of two animal models—the radially symmetric Aurelia aurita jellyfish, and the bilaterally symmetric Danio rerio zebrafish—to evaluate their turning dynamics. Both began turns with a small, rapid shift in body kinematics that preceded major axial rotation. Although small in absolute magnitude, the high fluid accelerations achieved by these initial motions generated powerful pressure gradients that maximized torque at the start of a turn. This pattern allows these animals to initially maximize torque production before major body curvature changes. Both animals then subsequently minimized the moment of inertia, and hence resistance to axial rotation, by body bending. This sequential solution provides insight into the advantages of re-arranging mass by bending during routine swimming turns

    By the People: Hard Times, Hard Choices Michigan Residents Deliberate

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    Outlines the concept of deliberative polling and presents results from a face-to-face statewide deliberative poll on Michigan's economy and budget issues, including taxes, spending and benefits, the environment, and options for state assistance.For the first time, a scientific random sample of the people of Michigan gathered together to deliberate about the hard choices facing the state's economic future. Results of Michigan's first Deliberative Poll show what the people of the state would think if they could all become more informed and discuss the issues in depth. Highly representative in both attitudes and demographics, a sample of 314 participants deliberated for a long weekend in Lansing, with both small group discussions and questions answered by competing experts in plenary sessions. The resulting changes of opinion in the final survey offer some dramatic recommendations for both policymakers and the public

    Saponite Dissolution Experiments and Implications for Mars

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    Recent work suggests that the mineralogical sequence of the Murray formation at Gale crater may have resulted from diagenetic alteration after sedimentation, or deposition in a stratified lake with oxic surface and anoxic bottom waters. Fe-containing clay minerals are common both at Gale crater, and throughout the Noachian-aged terrains on Mars. These clay minerals are primarily ferric (Fe3+), and previous work suggests that these ferric clay minerals may result from alteration of ferrous (Fe2+) smectites that were oxidized after deposition. The detection of trioctahedral smectites at Gale crater by CheMin suggests Fe2+ smectite was also deposited during the early Hesperian. However, due to their sensitivity to oxygen, Fe2+ smectites are difficult to analyze on Earth and very few saponite dissolution rates exist in the literature. To the best of our knowledge, no experiments have measured the dissolution rates of ferrous saponites under oxidizing and reducing conditions. In order to better understand the characteristics of water-rock interaction at Gale crater, particularly the oxidation state, we report our results to date on ongoing syntheses of ferrous and magnesium saponites and dissolution experiments of natural saponite under ambient conditions. Future experiments will include the dissolution of synthetic ferric, ferrous, and magnesium saponites under oxidizing and anoxic conditions at a range of pH values

    Historical institutionalism and the politics of sustainable energy transitions: a research agenda

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    Improving the understanding of the politics of sustainable energy transitions has become a major focus for research. This paper builds on recent interest in institutionalist approaches to consider in some depth the agenda arising from a historical institutionalist perspective on such transitions. It is argued that historical institutionalism is a valuable complement to socio-technical systems approaches, offering tools for the explicit analysis of institutional dynamics that are present but implicit in the latter framework, opening up new questions and providing useful empirical material relevant for the study of the wider political contexts within which transitions are emerging. Deploying a number of core concepts including veto players, power, unintended consequences, and positive and negative feedback in a variety of ways, the paper explores research agendas in two broad areas: understanding diversity in transition outcomes in terms of the effects of different institutional arrangements, and the understanding of transitions in terms of institutional development and change. A range of issues are explored, including: the roles of electoral and political institutions, regulatory agencies, the creation of politically credible commitment to transition policies, power and incumbency, institutional systems and varieties of capitalism, sources of regime stability and instability, policy feedback effects, and types of gradual institutional change. The paper concludes with some observations on the potential and limitations of historical institutionalism, and briefly considers the question of whether there may be specific institutional configurations that would facilitate more rapid sustainable energy transitions

    Clear purpose or sheer survival? National ministerial leadership across multiple arenas

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    Day-to-day political life for the most senior national politicians can be very pressurized and exposed. How they as individuals cope with constant challenges and make the most of opportunities for leadership is an under researched area. This is addressed in this interpretive study of the personal accounts of a small group of prominent U.K. politicians as they reflect, soon after leaving office, on their experiences as national ministers. The article connects generic leadership theory around practice and purpose with political leadership studies as a basis for a thematic analysis of ministers’ experiences across three key prominent arenas of ministerial life: relationships with the Prime Minister’s office, within their departments, and with their constituencies. Analysis of findings leads to a proposed analytical framework of active leadership in their everyday experience. The article concludes that active leadership practice is difficult but possible for leading national politicians

    Engineered expression of the invertebrate‐specific scorpion toxin AaHIT reduces adult longevity and female fecundity in the diamondback moth Plutella xylostella

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    Background: Previous Genetic Pest Management (GPM) systems in diamondback moth (DBM) have relied on expressing lethal proteins (‘effectors’) that are ‘cell‐autonomous’ 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 cell‐autonomous, invertebrate‐specific, neurotoxic effector – 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 ‘shaking/quivering’ phenotype which could be repressed by provision of an antidote (tetracycline); a phenotype consistent with the AaHIT mode‐of‐action. 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 (‐81%) and median female fecundity (‐93%). qPCR of AaHIT expression patterns and analysis of piggyBac‐mediated transgene insertion sites suggest that restriction of observed effects to the adult stages may be due to influence of local genomic environment on the tetO‐AaHIT transgene. Conclusion: We have demonstrated the feasibility of using non cell‐autonomous 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
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