18 research outputs found
Contextualized Knowledge Acquisition in a Personal Semantic Wiki
Abstract. The use of semantic representations in document-oriented environments â as formal annotations or embedded instances of a formal knowledge base â is seen as an enabling technology for intelligent services which may help knowledge workers in tasks like finding, structuring, or assessing information. Also, a high level of formalization has potential to directly support problem solving, e.g., by the application of inferencing services. A coupling of textual and formal representations in documentcentered knowledge work raises, amongst others, two questions: i) How can the acquisition of formal knowledge in such an environment be facilitated? ii) How can the potential complexity of formal annotations during a documentâs life and use cycle be adequately handled? We present the Mymory workbench as an approach to investigate and tackle these challenges. Mymory is based on a semantic wiki system and supports manual as well as automated annotations of wiki documents. These annotations can be framed by automatically obtained models o
Determining the contributions of protein synthesis and breakdown to muscle atrophy requires nonâsteadyâstate equations
Abstract Background Ageing and cachexia cause a loss of muscle mass over time, indicating that protein breakdown exceeds protein synthesis. Deuterium oxide (D2O) is used for studies of protein turnover because of the advantages of longâterm labelling, but these methods introduce considerations that have been largely overlooked when studying conditions of protein gain or loss. The purpose of this study was to demonstrate the importance of accounting for a change in protein mass, a nonâsteady state, during D2O labelling studies while also exploring the contribution of protein synthesis and breakdown to denervationâinduced muscle atrophy. Methods Adult (6 months) male C57BL/6 mice (n = 14) were labelled with D2O for a total of 7 days following unilateral sciatic nerve transection to induce denervation of hindlimb muscles. The contralateral sham limb and nonsurgical mice (n = 5) were used as two different controls to account for potential crossover effects of denervation. We calculated gastrocnemius myofibrillar and collagen protein synthesis and breakdown assuming steadyâstate or using nonâsteadyâstate modelling. We measured RNA synthesis rates to further understand ribosomal turnover during atrophy. Results Gastrocnemius mass was less in denervated muscle (137 ± 9 mg) compared with sham (174 ± 15 mg; P < 0.0001) or nonsurgical control (162 ± 5 mg; P < 0.0001). With steadyâstate calculations, fractional synthesis and breakdown rates (FSR and FBR) were lower in the denervated muscle (1.49 ± 0.06%/day) compared with sham (1.81 ± 0.09%/day; P < 0.0001) or nonsurgical control (2.27 ± 0.04%/day; P < 0.0001). When adjusting for change in protein mass, FSR was 4.21 ± 0.19%/day in denervated limb, whereas FBR was 4.09 ± 0.22%/day. When considering change in protein mass (ksyn), myofibrillar synthesis was lower in denervated limb (2.44 ± 0.14 mg/day) compared with sham (3.43 ± 0.22 mg/day; P < 0.0001) and nonâsurgical control (3.74 ± 0.12 mg/day; P < 0.0001), whereas rate of protein breakdown (kdeg, 1/t) was greater in denervated limb (0.050 ± 0.003) compared with sham (0.019 ± 0.001; P < 0.0001) and nonsurgical control (0.023 ± 0.000; P < 0.0001). Muscle collagen breakdown was completely inhibited during denervation. There was a strong correlation (r = 0.83, P < 0.001) between RNA and myofibrillar protein synthesis in sham but not denervated muscle. Conclusions We show conflicting results between steadyâ and nonâsteadyâstate calculations on myofibrillar protein synthesis and breakdown during periods of muscle loss. We also found that collagen accumulation was largely from a decrease in collagen breakdown. Comparison between sham and nonâsurgical control demonstrated a crossover effect of denervation on myofibrillar protein synthesis and ribosomal biogenesis, which impacts study design for unilateral atrophy studies. These considerations are important because not accounting for them can mislead therapeutic attempts to maintain muscle mass
A framework for conceptualizing, representing, and analyzing distributed interaction.
The relationship between interaction and learning is a central concern of the learning sciences, and analysis of interaction has emerged as a major theme within the current literature on computersupported collaborative learning. The nature of technology-mediated interaction poses analytic challenges. Interaction may be distributed across actors, space, and time, and vary from synchronous, quasi-synchronous, and asynchronous, even within one data set. Often multiple media are involved and the data comes in a variety of formats. As a consequence, there are multiple analytic artifacts to inspect and the interaction may not be apparent upon inspection, being distributed across these artifacts. To address these problems as they were encountered in several studies in our own laboratory, we developed a framework for conceptualizing and representing distributed interaction. The framework assumes an analytic concern with uncovering or characterizing the organization of interaction in sequential records of events. The framework includes a media independent characterization of the most fundamental unit of interaction, which we call uptake. Uptake is present when a participant takes aspects of prior events as having relevance for ongoing activity. Uptake can be refined into interactional relationships of argumentation, information sharing, transactivity, and so forth. for specific analytic objectives. Faced with the myriad of ways in which uptake can manifest in practice, we represent data using graphs of relationships between events that capture the potential ways in which one act can be contingent upon another. These contingency graphs serve as abstract transcripts that document in one representation interaction that is distributed across multiple media. This paper summarizes the requirements that motivate the framework, and discusses the theoretical foundations on which it is based. It then presents the framework and its application in detail, with examples from our work to illustrate how we have used it to support both ideographic and nomothetic research, using qualitative and quantitative methods. The paper concludes with a discussion of the frameworkâs potential role in supporting dialogue between various analytic concerns and methods represented in CSCL