Coordinating visualizations of polysemous action: Values added for grounding proportion

We contribute to research on visualization as an epistemic learning tool by inquiring into the didactical potential of having students visualize one phenomenon in accord with two different partial meanings of the same concept. 22 Grade 4-6 students participated in a design study that investigated the emergence of proportional-equivalence notions from mediated perceptuomotor schemas. Working as individuals or pairs in tutorial clinical interviews, students solved non-symbolic interaction problems that utilized remote-sensing technology. Next, they used symbolic artifacts interpolated into the problem space as semiotic means to objectify in mathematical register a variety of both additive and multiplicative solution strategies. Finally, they reflected on tensions between these competing visualizations of the space. Micro-ethnographic analyses of episodes from three paradigmatic case studies suggest that students reconciled semiotic conflicts by generating heuristic logico-mathematical inferences that integrated competing meanings into cohesive conceptual networks. These inferences hinged on revisualizing additive elements multiplicatively. Implications are drawn for rethinking didactical design for proportions. © 2013 FIZ Karlsruhe

SYM, Chern-Simons, Wess-Zumino Couplings and their higher derivative corrections in IIA Superstring theory

We find the entire form of the amplitude of two fermion strings (with different chirality), a massless scalar field and one closed string Ramond-Ramond (RR) in IIA superstring theory which is different from its IIB one. We make use of a very particular gauge fixing and explore several new couplings in IIA. All infinite $u$- channel scalar poles and $t,s$- channel fermion poles are also constructed. We find new form of higher derivative corrections to two fermion two scalar couplings and show that the first simple $(s+t+u)-$ channel scalar pole for $p+2=n$ case can be obtained by having new higher derivative corrections to SYM couplings at third order of $\alpha'$. We find that the general structure and the coefficients of higher derivative corrections to two fermion two scalar couplings are completely different from the derived $\alpha'$ higher derivative corrections of type IIB.Comment: 29 pages, no figure,Latex file,published version in EPJ

Scalable Peer-to-Peer Streaming for Live Entertainment Content

We present a system for streaming live entertainment content over the Internet originating from a single source to a scalable number of consumers without resorting to centralized or provider-provisioned resources. The system creates a peer-to-peer overlay network, which attempts to optimize use of existing capacity to ensure quality of service, delivering low startup delay and lag in playout of the live content. There are three main aspects of our solution: first, a swarming mechanism that constructs an overlay topology for minimizing propagation delays from the source to end consumers; second, a distributed overlay anycast system that uses a location-based search algorithm for peers to quickly find the closest peers in a given stream; and finally, a novel incentive mechanism that encourages peers to donate capacity even when the user is not actively consuming content

Nature of band-gap states in V-doped TiO2 revealed by resonant photoemission

Band-gap states in V-doped TiO2 have been studied by photoemission spectroscopy over a range of photon energies encompassing the Ti 3p and V 3p core thresholds. The states show resonant enhancement at photon energies significantly higher than found for Ti 3d states introduced into TiO2 by oxygen deficiency or alkalimetal adsorbates. This demonstrates that the gap states relate to electrons trapped on dopant V cations rather than host Ti cations

Continuous functions with universally divergent Fourier series on small subsets of the circle

It is shown that quasi all continuous functions on the unit circle have the property that, for many small subsets E of the circle, the partial sums of their Fourier series considered as functions restricted to E exhibit certain universality properties.Comment: 6 page

Effective Capacity in Broadcast Channels with Arbitrary Inputs

We consider a broadcast scenario where one transmitter communicates with two receivers under quality-of-service constraints. The transmitter initially employs superposition coding strategies with arbitrarily distributed signals and sends data to both receivers. Regarding the channel state conditions, the receivers perform successive interference cancellation to decode their own data. We express the effective capacity region that provides the maximum allowable sustainable data arrival rate region at the transmitter buffer or buffers. Given an average transmission power limit, we provide a two-step approach to obtain the optimal power allocation policies that maximize the effective capacity region. Then, we characterize the optimal decoding regions at the receivers in the space spanned by the channel fading power values. We finally substantiate our results with numerical presentations.Comment: This paper will appear in 14th International Conference on Wired&Wireless Internet Communications (WWIC

The Complexity of Routing with Few Collisions

We study the computational complexity of routing multiple objects through a network in such a way that only few collisions occur: Given a graph $G$ with two distinct terminal vertices and two positive integers $p$ and $k$, the question is whether one can connect the terminals by at least $p$ routes (e.g. paths) such that at most $k$ edges are time-wise shared among them. We study three types of routes: traverse each vertex at most once (paths), each edge at most once (trails), or no such restrictions (walks). We prove that for paths and trails the problem is NP-complete on undirected and directed graphs even if $k$ is constant or the maximum vertex degree in the input graph is constant. For walks, however, it is solvable in polynomial time on undirected graphs for arbitrary $k$ and on directed graphs if $k$ is constant. We additionally study for all route types a variant of the problem where the maximum length of a route is restricted by some given upper bound. We prove that this length-restricted variant has the same complexity classification with respect to paths and trails, but for walks it becomes NP-complete on undirected graphs

The Hardness of Embedding Grids and Walls

The dichotomy conjecture for the parameterized embedding problem states that the problem of deciding whether a given graph $G$ from some class $K$ of "pattern graphs" can be embedded into a given graph $H$ (that is, is isomorphic to a subgraph of $H$) is fixed-parameter tractable if $K$ is a class of graphs of bounded tree width and $W[1]$-complete otherwise. Towards this conjecture, we prove that the embedding problem is $W[1]$-complete if $K$ is the class of all grids or the class of all walls

Shale Public Finance: Local government revenues and costs associated with oil and gas development

Oil and gas development associated with shale resources has increased substantially in the United States, with important implications for local governments. These governments tend to experience increased revenue from a variety of sources, such as severance taxes distributed by the state government, local property taxes and sales taxes, direct payments from oil and gas companies, and in-kind contributions from those companies. Local governments also tend to face increased demand for services such as road repairs due to heavy truck traffic and from population growth associated with the oil and gas sector. This paper describes the major oil- and gas related revenues and service demands (i.e., costs) that county and municipal governments have experienced in Arkansas, Colorado, Louisiana, Montana, North Dakota, Pennsylvania, Texas, and Wyoming. Based on extensive interviews with officials in the most heavily affected parts of these states, along with analysis of financial data, it appears that most county and municipal governments have experienced net financial benefits, though some in western North Dakota and eastern Montana appear to have experienced net negative fiscal impacts. Some municipalities in rural Colorado and Wyoming also struggled to manage fiscal impacts during recent oil and gas booms, though these challenges faded as drilling activity slowed

Enhancing mechanics education through shared assessment design

© American Society for Engineering Education, 2016. There is considerable commonality between engineering undergraduate programs in terms of content, pedagogies, course structures and assessment practices, particularly in terms of engineering fundamentals such as mechanics. Despite this, and the availability of an array of online resources, there seems to be limited commitment to sharing learning resources among teaching academics and between institutions. Further, there seems to be a specific resistance to sharing those materials that support the teaching and learning of technical content1. Collaborations seen in research networks seem not to have equivalent presence in teaching and learning, despite a literature that points to the benefits of sharing curriculum resources 2,3. A few projects funded by the Federal Office for Learning and Teaching (OLT) in Australia have made freely available resources as deliverables (A proactive approach to addressing student learning diversity in engineering mechanics 4; Promoting student engagement and continual improvement: Integrating professional quality management practice into engineering curricula5; Remotely accessible laboratories: Enhancing learning outcomes6 and many more 7). There has been varied uptake of these, however, and the long-term maintenance of online resources is problematic. There is also a literature that identifies sustainability challenges with open educational resources including funding and intellectual property rights 3. It could be argued that failure to provide resources and, concomitantly the uptake by teaching academics of such resources impedes student access to these resources and therefore impacts their learning. It also contributes to inefficiencies brought about by work duplication. The reasons for limited uptake of resources are both institutional and individual. However, there are nuances to what is meant by a resource, how resources are modified by academics and where in a program they might be used 1. For the purposes of this paper, we are looking at resources designed to assist in the learning and teaching of engineering mechanics. This paper presents the results of a workshop held as part of a project, funded by the Australian Council of Engineering Deans (ACED), to promote curriculum sharing across the 35 universities in Australia that teach engineering. It includes a description and analysis of the activities, an analysis of the workshop evaluation as well as one participant's reflection on the process