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References 1, 5 introduce a transport protocol that o ers partially ordered service for multimedia applications. This paper investigates how m uch the selection of a linear extension a ects system performance in a partially ordered service. We rst show h o w t o identify better linear extensions of a partial order, and then determine the performance gains by using such linear extensions at the time of transmission. To quantify linear extensions of a partial order, we propose a new metric pBuf -metric that is derived from bu ering probabilities. Since pBuf -metric is complex to calculate, a simpli ed version called -metric is also investigated. An OPNET simulation shows that for certain partial orders, a linear extension optimized according to these metrics provides some delay, and signi cant bu er utilization improvements over a non-optimal linear extension. Thus, prudent transmission order selection in a partially ordered service does improve system performance. Results also show that, in general, -metric is as e ective a s pBuf -metric in identifying better linear extensions of a partial order.

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Many institutions have created and deployed outreach programs for middle school students with the goal of increasing the number and diversity of students who later pursue careers in computer science. While these programs have been shown to increase interest in computer science, there has been less work on showing whether participants learn computer science content.We address two questions, one specific, and the other more general: (1) "What computer science did our middle school students learn in our interdisciplinary two-week summer camp?" (2) "How can computer science concepts be assessed in the context of Scratchbased outreach programs"? We address both questions by presenting the design of our summer camp, an overview of our curriculum, our assessment methodology, and our assessment results.Though the sample size is not statistically significant, the results show that a two-week, interdisciplinary, non-academic summer camp can be effective not only for engaging students, but also for imparting CS content. In just two weeks, with a curriculum not entirely focused on computer science, students displayed competence with event-driven programming, initialization of state, message passing, and say/sound synchronization 1 . We have employed assessment methodologies that avoid written exams, an approach both outreach and classroom-based programs may find useful.

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