There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

creased by 0.47 SDs under active learning (n = 158 studies), and that the odds ratio for failing was 1.95 under traditional lecturing (n = 67 studies). These results indicate that average examination scores improved by about 6% in active learning sections, and that students in classes with traditional lecturing were 1.5 times more likely to fail than were students in classes with active learning. Heterogeneity analyses indicated that both results hold across the STEM disciplines, that active learning increases scores on concept inventories more than on course examinations, and that active learning appears effective across all class sizes—although the greatest effects are in small (n ≤ 50) classes. Trim and fill analyses and fail-safe n calculations suggest that the results are not due to publication bias. The results also appear robust to variation in the methodological rigor of the included studies, based on the quality of controls over student quality and instructor identity. This is the largest and most comprehensive metaanalysis of undergraduate STEM education published to date. The results raise questions about the continued use of traditional lecturing as a control in research studies, and support active learning as the preferred, empirically validated teaching practice in regular classrooms.

/pdf/active-learning-increases-student-performance-in-science-3j0c6wu4k5.pdf

Active learning increases student performance in science, engineering, and mathematics

A wide variety of media can be used in learning, including distance learning, such as print, lectures, conference sections, tutors, pictures, video, sound, and computers. Any one instance of distance learning will make choices among these media, perhaps using several.

Multimedia in Learning

In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Evolution and the Theory of Games

What Video Games Have to Teach Us about Learning and Literacy

The capacity problem in wireless mesh networks can be alleviated by equipping the mesh routers with multiple radios tuned to non-overlapping channels However, channel assignment presents a challenge because co-located wireless networks are likely to be tuned to the same channels The resulting increase in interference can adversely affect performance This paper presents an interference-aware channel assignment algorithm and protocol for multi-radio wireless mesh networks that address this interference problem The proposed solution intelligently assigns channels to radios to minimize interference within the mesh network and between the mesh network and co-located wireless networks It utilizes a novel interference estimation technique implemented at each mesh router An extension to the conflict graph model, the multi-radio conflict graph, is used to model the interference between the routers We demonstrate our solution’s practicality through the evaluation of a prototype implementation in a IEEE 80211 testbed We also report on an extensive evaluation via simulations In a sample multi-radio scenario, our solution yields performance gains in excess of 40% compared to a static assignment of channels

/pdf/interference-aware-channel-assignment-in-multi-radio-2ald9axdtc.pdf

Interference-Aware Channel Assignment in Multi-Radio Wireless Mesh Networks

One of the most important methods for evaluating the characteristics of ad hoc networking protocols is through the use of simulation. Simulation provides researchers with a number of significant benefits, including repeatable scenarios, isolation of parameters, and exploration of a variety of metrics. The topology and movement of the nodes in the simulation are key factors in the performance of the network protocol under study. Once the nodes have been initially distributed, the mobility model dictates the movement of the nodes within the network. Because the mobility of the nodes directly impacts the performance of the protocols, simulation results obtained with unrealistic movement models may not correctly reflect the true performance of the protocols. The majority of existing mobility models for ad hoc networks do not provide realistic movement scenarios; they are limited to random walk models without any obstacles. In this paper, we propose to create more realistic movement models through the incorporation of obstacles. These obstacles are utilized to both restrict node movement as well as wireless transmissions. In addition to the inclusion of obstacles, we construct movement paths using the Voronoi diagram of obstacle vertices. Nodes can then be randomly distributed across the paths, and can use shortest path route computations to destinations at randomly chosen obstacles. Simulation results show that the use of obstacles and pathways has a significant impact on the performance of ad hoc network protocols.

/pdf/towards-realistic-mobility-models-for-mobile-ad-hoc-networks-3fd07ugaq4.pdf

Towards realistic mobility models for mobile ad hoc networks

Clickers in college classrooms: Fostering learning with questioning methods in large lecture classes

In typical proposals for video-on-demand (VoD) systems, customers are serviced individually by allocating and dedicating a transmission channel and a set of server resources to each customer. This approach leads to an expensive to operate, nonscalable system. We consider a VoD system that uses multicast delivery to service multiple customers with a single set of resources. The use of multicast communication requires that part of the on-demand nature of the system be sacrificed to achieve scalability and cost-effectiveness. One drawback to using multicast communication is that it complicates the provision or interactive VCR-style functions. Interactivity can be provided by either increasing the complexity of the customer set-top box (STB) or by modifying the semantics of the interactive functions to make them easier to provide. We describe a framework and mechanisms by which such interactive functions can be incorporated into a multicast delivery VoD system. Through the use of simulation, we evaluate and compare the performance of a unicast VoD system and multicast VoD systems offering various levels of interactivity.

The use of multicast delivery to provide a scalable and interactive video-on-demand service

Multicast communication-the one-to-many or many-to-many delivery of data-is a hot topic. It is of interest in the research community, among standards groups, and to network service providers. For all the attention multicast has received, there are still issues that have not been completely resolved. One result is that protocols are still evolving, and some standards are not yet finished. From a deployment perspective, the lack of standards has slowed progress, but efforts to deploy multicast as an experimental service are in fact gaining momentum. The question now is how long it will be before multicast becomes a true Internet service. The goal of this article is to describe the past, present, and future of multicast. Starting with the Multicast Backbone (MBone), we describe how the emphasis has been on developing and refining intradomain multicast routing protocols. Starting in the middle to late 1990s, particular emphasis has been placed on developing interdomain multicast routing protocols. We provide a functional overview of the currently deployed solution. The future of multicast may hinge on several research efforts that are working to make the provision of multicast less complex by fundamentally changing the multicast model. We survey these efforts. Finally, attempts are being made to deploy native multicast routing in both Internet2 networks and the commodity Internet. We examine how multicast is being deployed in these networks.

/pdf/the-evolution-of-multicast-from-the-mbone-to-interdomain-3v09kkwdm8.pdf

Kevin C. Almeroth

Papers

Interference-Aware Channel Assignment in Multi-Radio Wireless Mesh Networks

Towards realistic mobility models for mobile ad hoc networks

Clickers in college classrooms: Fostering learning with questioning methods in large lecture classes

The use of multicast delivery to provide a scalable and interactive video-on-demand service

The evolution of multicast: from the MBone to interdomain multicast to Internet2 deployment