The Finite Field Multi-Way Relay Channel with Correlated Sources: Beyond Three Users

The multi-way relay channel (MWRC) models cooperative communication networks in which many users exchange messages via a relay. In this paper, we consider the finite field MWRC with correlated messages. The problem is to find all achievable rates, defined as the number of channel uses required per reliable exchange of message tuple. For the case of three users, we have previously established that for a special class of source distributions, the set of all achievable rates can be found [Ong et al., ISIT 2010]. The class is specified by an almost balanced conditional mutual information (ABCMI) condition. In this paper, we first generalize the ABCMI condition to the case of more than three users. We then show that if the sources satisfy the ABCMI condition, then the set of all achievable rates is found and can be attained using a separate source-channel coding architecture.Comment: Author's final version (to be presented at ISIT 2012

Inferring Concept Prerequisite Relations from Online Educational Resources

The Internet has rich and rapidly increasing sources of high quality educational content. Inferring prerequisite relations between educational concepts is required for modern large-scale online educational technology applications such as personalized recommendations and automatic curriculum creation. We present PREREQ, a new supervised learning method for inferring concept prerequisite relations. PREREQ is designed using latent representations of concepts obtained from the Pairwise Latent Dirichlet Allocation model, and a neural network based on the Siamese network architecture. PREREQ can learn unknown concept prerequisites from course prerequisites and labeled concept prerequisite data. It outperforms state-of-the-art approaches on benchmark datasets and can effectively learn from very less training data. PREREQ can also use unlabeled video playlists, a steadily growing source of training data, to learn concept prerequisites, thus obviating the need for manual annotation of course prerequisites.Comment: Accepted at the AAAI Conference on Innovative Applications of Artificial Intelligence (IAAI-19

Multi-Way Relay Networks: Orthogonal Uplink, Source-Channel Separation and Code Design

We consider a multi-way relay network with an orthogonal uplink and correlated sources, and we characterise reliable communication (in the usual Shannon sense) with a single-letter expression. The characterisation is obtained using a joint source-channel random-coding argument, which is based on a combination of Wyner et al.'s "Cascaded Slepian-Wolf Source Coding" and Tuncel's "Slepian-Wolf Coding over Broadcast Channels". We prove a separation theorem for the special case of two nodes; that is, we show that a modular code architecture with separate source and channel coding functions is (asymptotically) optimal. Finally, we propose a practical coding scheme based on low-density parity-check codes, and we analyse its performance using multi-edge density evolution.Comment: Authors' final version (accepted and to appear in IEEE Transactions on Communications

Strategies for Reducing High Turnover Among Information Technology Professionals

Organizations globally are spending millions of dollars replacing information technology (IT) professionals. IT professionals, who possess technical skills and competencies that interconnect business processes, are costly to replace. There are direct and indirect costs associated when an IT professional leaves, such as advertising fees, headhunting fees, and project delays. Lacking a firm understanding of the reasons why IT professionals leave their positions, many business leaders do not have strategies for reducing turnover rates. Building on Herzberg\u27s motivation-hygiene theory and March and Simon\u27s process model of turnover, this exploratory multiple case study sought to identify the strategies that business leaders view as essential for retaining IT professionals. Semistructured interviews were conducted with 10 IT managers in the Houston, Texas, area; participants were selected using a purposive sampling technique. Thematic analysis revealed eight strategies for addressing turnover: compensation, opportunity and advancement, rewards and recognition, relationship with the supervisor and coworkers, training and development, communications, meaningful work, and flexible work schedule. Findings from this study may contribute to positive social change by providing business leaders with more insight about how they can retain IT professionals. The high turnover among IT professionals affects individuals, families, communities, organizations, and the economy. Implementing strategies to reduce turnover rates can help keep individual employees and their family members together and reduce the unemployment rates

The swamp and mesic forests of the Cumberland Plateau in Tennessee

The swamp and mesic forest communities of the flat to rolling surface of the Cumberland Plateau in Tennessee were studied in the summer of 1976. Objectives were to determine the composition of these communities, and the relationships between and among important overstory taxa, soil, site, and regional variables. There were 137 plots sampled in nine counties on the Plateau. Eight forest types were described for this area. Red maple, white oak, and blackgum were the most important species in the study area. Correlation analyses were performed between and among 40 soil, site, regional variables and 10 overstory taxa importance values (I.V.)

Genetic diversity of the Brownsville common yellowthroat (Geothlypis trichas insperata).

Habitat fragmentation is particularly severe in the Lower Rio Grande Valley (LRGV) of south Texas, where an estimated 95% of the native brushland has been eliminated by agriculture and urban development. This fragmentation effectively divides bird populations into smaller "subpopulations within a population," or a metapopulation. Fragmentation has divided wetland habitat where wetlands are more dense close to the Rio Grande River and becomes more scattered north of the River. Therefore, bird species who utilize the wetlands close to the River should be denser and more closely related, genetically, than individuals farther north. A good model for studying the effects of fragmentation in the LRGV is the "Brownsville" Common Yellowthroat ix (Geothlypis trichas insperata), a subspecies of the Common Yellowthroat. Klicka (1994) studied the Brownsville Common Yellowthroat and concluded that they were restricted to the southern third of Cameron County and they were most common along the Rio Grande River. Several predictions were tested. (1) Apparent survivorship of Brownsville Yellowthroats in the LRGV has not changed since the 1988-1989 study conducted by Klicka (1994). (2) Linear density of Brownsville Yellowthroats is greatest nearer to the River. (3) I expect individuals on or near the Rio Grande River to be more closely related than northern individuals. (4) The source-sink metapopulation model should be the model best fit to describe this subspecies. Blood samples were collected from captured individuals (n = 128) for microsatellite testing. Samples were examined with a genetic analyzer and subjected to tests using programs STRUCTURE, CERVUS, GENEPOP, and RELATEDNESS. Apparent survivorship for this study (34%) was lower than that reported by Klicka (55%; 1994). The linear densities of sites near the Rio Grande River and far from the River were not significantly different. Analysis of genetic relatedness indicates that individuals are as related to each other as would be expected in distant relatives. Therefore, these data indicate that a single, admixed population is present in the LRGV which most closely resembles an open population model