We have recently developed an ultrasound-based velocimetry technique, termed echo particle image velocimetry (Echo PIV), to measure multi-component velocity vectors and local shear rates in arteries and opaque fluid flows by identifying and tracking flow tracers (ultrasound contrast microbubbles) within these flow fields. The original system was implemented on images obtained from a commercial echocardiography scanner. Although promising, this system was limited in spatial resolution and measurable velocity range. In this work, we propose standard rules for characterizing Echo PIV performance and report on a custom-designed Echo PIV system with increased spatial resolution and measurable velocity range. Then we employed this system for initial measurements on tube flows, rotating flows and in vitro carotid artery and abdominal aortic aneurysm (AAA) models to acquire the local velocity and shear rate distributions in these flow fields. The experimental results verified the accuracy of this technique and indicated the promise of the custom Echo PIV system in capturing complex flow fields non-invasively.

This letter reports on a contrast-based ultrasonic particle imaging technique (echo PIV) for measuring multicomponent velocity vectors in opaque flows with excellent temporal (up to 0.5ms) and spatial (up to 0.4mm) resolution. Ultrasound contrast microbubbles are used as flow tracers, and digitally acquired rf data are converted into B-mode images for PIV analysis. Here, velocity fields from various flow patterns (including rotating and transient vortex flows) that are difficult to measure using other opaque flow methods such as ultrasound Doppler or magnetic resonance imaging are measured using echo PIV. This nonintrusive technique should be a promising addition to opaque flow diagnostics.

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In this paper, we argue that there are patterns of innovation occurring in less economically developed countries (LEDCs) that have been historically overlooked by the innovation studies literature, including the literature on innovation systems and the triple helix. This paper briefly surveys cases in agriculture, banking, biomedicine and information and communications technologies that demonstrate organizational, scientific and technological innovation in Africa, South Asia, and Brazil. In particular, we track new developments in two distinctive patterns within LEDCs: (1) civil society as a site of innovation and; (2) innovation through appropriation. By systematically uncovering patterns of innovation in LEDCs, science and technology policy scholars may make new theoretical gains in innovation studies that can potentially contribute to innovation policies in the global South.

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Systemic injustices exclude counter-experts from telling their stories and influencing the collective imagination. Four papers and some discussant essays illustrate the ways in which counter-experts cross boundaries to contest knowledge claims, legal institutions, and forms of data in order to resist various forms of injustice. Literature on counter-expertise, socio-technical imaginaries, and epistemic injustice highlights how marginalized groups are prevented from participating in the process of collective imagining. A definition of counter-expertise and a new typology of counter-expertise demonstrate how marginalized groups navigate boundaries to pursue epistemic justice. The four papers in the special issue exemplify the ways in which counter-experts navigate identity politics. To combat epistemic injustice within our field, STS scholars can be more inclusive with teaching, mentoring, reviewing and other forms of scholarly gatekeeping.

This paper describes a new shift in the appropriate technology movement in less economically developed countries as seen in a multi-sited ethnography of non-govemmental organizations (NGOs) in the scientific field of ophthalmology. This research reveals how Aravind Eye Care System in southern India and Tilganga Institute of Ophthalmology in Nepal are addressing "undone science" for avoidable blindness. They are creating the requisite local hospital and personnel infrastructure while conducting "civil society research." They are also providing high quality modern care to low-income patients of the global south while charging reduced or no fees. This paper argues that they represent a third model in the appropriate technology movement-contextually appropriate local production of high technology. This third model focuses on socially responsible innovation for purposes of social improvement; it is rooted in nonprofit, social enterprise organizations to include the following four aspects: (1) scientific innovation or the "appropriation" of new science; (z) organizational innovation, including changes in operations management for self-sufficiency through multiple revenue streams; (3) technological innovation or the creation of new products and artifacts; and (4) an underlying ideological orientation that is based on local philosophy (and challenges hegemonic understandings of postcolonial dependency or neoliberalism).

The fieldwork upon which this article is based was funded by the CAORC Multi-Country Fellowship and the NSF DDIG 1153308. Thanks are owed to Ron Eglash for his comments on an early draft, to Megan Wudkewych for her research assistance and to the anonymous reviewers and Amit Prasad for their editorial suggestions.