2,196 research outputs found

    Gas gun shock experiments with single-pulse x-ray phase contrast imaging and diffraction at the Advanced Photon Source

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    The highly transient nature of shock loading and pronounced microstructure effects on dynamic materials response call for {\it in situ}, temporally and spatially resolved, x-ray-based diagnostics. Third-generation synchrotron x-ray sources are advantageous for x-ray phase contrast imaging (PCI) and diffraction under dynamic loading, due to their high photon energy, high photon fluxes, high coherency, and high pulse repetition rates. The feasibility of bulk-scale gas gun shock experiments with dynamic x-ray PCI and diffraction measurements was investigated at the beamline 32ID-B of the Advanced Photon Source. The x-ray beam characteristics, experimental setup, x-ray diagnostics, and static and dynamic test results are described. We demonstrate ultrafast, multiframe, single-pulse PCI measurements with unprecedented temporal (<<100 ps) and spatial (∼\sim2 μ\mum) resolutions for bulk-scale shock experiments, as well as single-pulse dynamic Laue diffraction. The results not only substantiate the potential of synchrotron-based experiments for addressing a variety of shock physics problems, but also allow us to identify the technical challenges related to image detection, x-ray source, and dynamic loading

    Indigenous knowledges and development: a postcolonial caution

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    As a result of the failure of formal top-down development, there has recently been increased interest in the possibilities of drawing upon the indigenous knowledges of those in the communities involved, in an attempt to produce more effective development strategies. The concept of indigenous knowledge calls for the inclusion of local voices and priorities, and promises empowerment through ownership of the process. However, there has been little critical examination of the ways in which indigenous knowledges have been included in the development process. Drawing upon postcolonial theory, this article suggests that indigenous knowledges are often drawn into development by both theorists and development institutions in a very limited way, failing to engage with other ways of perceiving development, and thus missing the possibility of devising more challenging alternatives

    ‘No expectations’: straight men's sexual and moral identity-making in non-monogamous dating

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    This article juxtaposes the discursive strategies of two groups of heterosexual men in the context of non-monogamous internet-mediated dating in Belgium, notably men who are open about their extra-dyadic sexual practices and 'cheating' men. The analysis shows that regardless of the men's use of openness or discretion to construct narratives of sexual identity, morality and care, their accounts seem to be deeply intertwined with monogamist and gendered ideas on sex, care and commitment, which serves to define a largely uncaring and consumeristic dating culture. The article argues that attentiveness to power inequalities should be the main focus of 'ethical' non-monogamy

    Situated solidarities and the practice of scholar-activism

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    Drawing on an analysis of an ongoing collaboration with rural peasant movements in Bangladesh, we explore the possibility of forging solidarity through practices of scholar-activism. In so doing, we consider the practice of reflexivity, reconsider forms of solidarity, and draw on the concept of convergence spaces as a way to envision sites of possibility. We mobilize the notion of situated solidarities to propose an alternative form of reflexive practice in scholarship. We then posit that there are six ‘practices’ that provide a useful schematic for thinking through the opportunities for the construction of these solidaritie

    Situationally edited empathy: an effect of socio-economic structure on individual choice

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    Criminological theory still operates with deficient models of the offender as agent, and of social influences on the agent’s decision-making process. This paper takes one ‘emotion’, empathy, which is theoretically of considerable importance in influencing the choices made by agents; particularly those involving criminal or otherwise harmful action. Using a framework not of rational action, but of ‘rationalised action’, the paper considers some of the effects on individual psychology of social, economic, political and cultural structure. It is suggested that the climate-setting effects of these structures promote normative definitions of social situations which allow unempathic, harmful action to be rationalised through the situational editing of empathy. The ‘crime is normal’ argument can therefore be extended to include the recognition that the uncompassionate state of mind of the criminal actor is a reflection of the self-interested values which govern non-criminal action in wider society
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