The oral bioaccessibility of soil contaminants is increasingly assessed with physiologically based extraction tests (PBETs): the contaminant fraction that is desorbed into simulated digestive fluids is measured and classified as bioaccessible. However, this approach can lead to underestimations if the capacity of the fluids is insufficient to provide infinite sink conditions. Desorption will then progressively decrease and finally stop when equilibrium between soil and medium is reached. To circumvent this artifact, we incorporated a silicone rod as an absorption sink into the PBET to continuously absorb mobilized contaminants and maintain the desorption gradient. Polycyclic aromatic hydrocarbons served as model contaminants and the colon extended PBET as the extraction model. The inclusion of the silicone rod sink (1) increased the extraction capacity of the test by orders of magnitude, (2) ensured near infinite sink conditions, and (3) allowed for simple back-extraction of PAHs for their quantification by GC-MS. The silicone rod provided fast enrichment when applied to the stomach and small intestine compartment, but was somewhat slower in the richer colon compartment. Finally, the sorptive-PBET was applied to wood soot and a kindergarten soil. The present article provides the basis for how an absorption sink can be integrated into PBET models.
Our point of departure is that the relationship between social science, cooperative working and technology is not as much a matter of differences in understanding, as it is a matter of how to accomplish change. This chapter outlines an approach to design of CSCW where change is addressed in terms of expansion of the work practice. To facilitate the change process as a process of expansion, scenarios are used as springboards. Creation and use of scenarios are supported by a conceptual toolbox. The foundation for this toolbox is an understanding of the design process as abductive thinking consisting of idea generation and systematic reflection, and an understanding of design tools inspired from activity theory. As design processes may involve different communities of practice, we discuss the role of scenarios as boundary objects.
This paper examines the affordance of the Danish social networking site www.mingler.dk for peer-to-peer learning and development. With inspiration from different theoretical frameworks, we argue how learning and development in such social online systems can be conceptualised and analysed. Theoretically the paper defines development in accordance with Vygotsky's concept 'Zone Of Proximal development [ZOP], and learning in accordance with Wenger's concept 'Communities of Practice' [COP]. We suggest analysing the learning and development taking place on www.mingler.dk by using these concepts supplemented by the notion of horizontal learning adopted from Engeström and Wenger. Our analysis shows how horizontal learning happens by crossing boundaries between several sites of engagement, and how the actors' multimembership enables the community members to draw on a vast amount of resources from a multiplicity of sites. We show how the members thereby also become (co)producers of such resources, which then in turn become resources for other communities.
Abstract. How do we conceptualize social awareness, and what support is needed to develop and maintain social awareness in flexible work settings? The paper begins by arguing the relevance of designing for social awareness in flexible work. It points out how social awareness is suspended in the field of tension that exists between the ephemerality and continuity of social encounters, exploring ways to construct identity through relationships by means of social encounters -notably those that are accidental and unforced. We probe into this issue through design research: In particular, we present three exploratory prototyping processes in an open office setting (examining the concepts of a shared calendar, personal panels, and ambient awareness cues). Field studies, conducted in parallel, have contributed to a conceptual deconstruction of CSCW concepts, resulting in a focus on cues to relatedness, to belonging, and to care. Analyzing these three prototypes in their microcosmic usage setting results in specific recommendations for the three types of applications with respect to social awareness. The experiences indicate that the metaphors a 'shared mirror' and 'breadcrumbs' are promising foundations on which to base further design. We present these analyses and suggest that the metaphors work because of their ability to map experiences from the physical space into conceptual experiences. We conclude that social awareness in flexible work must be constructed indirectly, presenting itself as an option, rather than as a consequence of being able to overhear and oversee.
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