International on-line reciprocal peer tutoring to promote modern language development in primary schools

The paper reports data from an on-line peer tutoring project. In the project 78, 9–12-year-old students from Scotland and Catalonia peer tutored each other in English and Spanish via a managed on-line environment. Significant gains in first language (Catalonian pupils) modern language (Scottish pupils) and attitudes towards modern languages (both Catalonian and Scottish pupils) were reported for the experimental group as compared to the control group. Results indicated that pupils tutored each other in using Piagetian techniques of error correction during the project. Error correction provided by tutors to tutees focussed on morph syntaxys, more specifically the correction of verbs. Peer support provided via the on-line environment was predominantly based on the tutor giving the right answer to the tutee. High rates of impact on tutee corrected messages were observed. The implications for peer tutoring initiative taking place via on-line environments are discussed. Implications for policy and practice are explored.     

Convergence for a family of discrete advection–reaction operators

We define a family of discrete Advection–reaction operators, denoted by $A_{a\lambda }$, which associate to a given scalar sequence $s=\left\{s_n\right\}$ the sequence given by $A_{a\lambda }\left(s\right)\equiv \left\{b_n\right\}$, where $b_n=a_{n?2}{s}_{n?1}+{\lambda }_n{s}_n$ for $n=1,2,\dots$. For $A_{a\lambda }$ we explicitly find their iterates and study their convergence properties. Finally, we show the relationship between the family of discrete operators with the continuous one dimensional advection–reaction equation.     

Design of highly synchronizable and robust networks

In this paper, the design of highly synchronizable, sparse and robust dynamical networks is addressed. Better synchronizability means faster synchronization of the oscillators, sparsity means a low ratio of links per nodes and robustness refers to the resilience of a network to the random failures or intentional removal of some of the nodes/links. Golden spectral dynamical networks (graphs) are those for which the spectral spread (the difference between the largest and smallest eigenvalues of the adjacency matrix) is equal to the spectral gap (the difference between the two largest eigenvalues of the adjacency matrix) multiplied by the square of the golden ratio. These networks display the property of “small-worldness”, are very homogeneous and have large isoperimetric (expansion) constant, together with a very high synchronizability and robustness to failures of individual oscillators. In particular, the regular bipartite dynamical networks, reported here by the first time, have the best possible expansion and consequently are the most robust ones against node/link failures or intentional attacks.     

Elicitation strategies for soft constraint problems with missing preferences: Properties,algorithms and experimental studies

We consider soft constraint problems where some of the preferences may be unspecified. This models, for example, settings where agents are distributed and have privacy issues, or where there is an ongoing preference elicitation process. In this context, we study how to find an optimal solution without having to wait for all the preferences. In particular, we define algorithms, that interleave search and preference elicitation, to find a solution which is necessarily optimal, that is, optimal no matter what the missing data will be, with the aim to ask the user to reveal as few preferences as possible. We define a combined solving and preference elicitation scheme with a large number of different instantiations, each corresponding to a concrete algorithm, which we compare experimentally. We compute both the number of elicited preferences and the user effort, which may be larger, as it contains all the preference values the user has to compute to be able to respond to the elicitation requests. While the number of elicited preferences is important when the concern is to communicate as little information as possible, the user effort measures also the hidden work the user has to do to be able to communicate the elicited preferences. Our experimental results on classical, fuzzy, weighted and temporal incomplete CSPs show that some of our algorithms are very good at finding a necessarily optimal solution while asking the user for only a very small fraction of the missing preferences. The user effort is also very small for the best algorithms.     

Discontinuous subgrid formulations for transport problems

In this paper we develop two discontinuous Galerkin formulations within the framework of the two-scale subgrid method for solving advection–diffusion-reaction equations. We reformulate, using broken spaces, the nonlinear subgrid scale (NSGS) finite element model in which a nonlinear eddy viscosity term is introduced only to the subgrid scales of a finite element mesh. Here, two new subgrid formulations are built by introducing subgrid stabilized terms either at the element level or on the edges by means of the residual of the approximated resolved scale solution inside each element and the jump of the subgrid solution across interelement edges. The amount of subgrid viscosity is scaled by the resolved scale solution at the element level, yielding a self adaptive method so that no additional stabilization parameter is required. Numerical experiments are conducted in order to demonstrate the behavior of the proposed methodology in comparison with some discontinuous Galerkin methods.     

Virtual Tree: A robust architecture for interval valid queries in dynamic distributed systems

This paper studies the problem of answering aggregation queries, satisfying the interval validity semantics, in a distributed system prone to continuous arrival and departure of participants. The interval validity semantics states that the query answer must be calculated considering contributions of at least all processes that remained in the distributed system for the whole query duration. Satisfying this semantics in systems experiencing unbounded churn is impossible due to the lack of connectivity and path stability between processes. This paper presents a novel architecture, namely Virtual Tree, for building and maintaining a structured overlay network with guaranteed connectivity and path stability in settings characterized by bounded churn rate. The architecture includes a simple query answering algorithm that provides interval valid answers. The overlay network generated by the Virtual Tree architecture is a tree-shaped topology with virtual nodes constituted by clusters of processes and virtual links constituted by multiple communication links connecting processes located in adjacent virtual nodes. We formally prove a bound on the churn rate for interval valid queries in a distributed system where communication latencies are bounded by a constant unknown by processes. Finally, we carry out an extensive experimental evaluation that shows the degree of robustness of the overlay network generated by the virtual tree architecture under different churn rates.     

Cross-cultural analysis in online community research: A literature review

Cross-cultural online community research can support theoretical generalizability, increase methodological robustness and give insights into user online behavior. The objective of this paper is to review the existing literature on comparative cross-cultural online community research in order to investigate the current state of the literature, extract conceptual patterns and identify methodological and emergent issues. This will inform the development of the field, map out research delimiters, and set out guidelines for future research. The findings from the literature review demonstrated five key areas of methodological difficulty in cross-cultural online community comparative analysis; sampling form, country selection, number of cultures compared, participant type and interpretation of data. Key themes that emerged from the literature included the use of the nation state as a unit of culture, a lack of definition of the concept of online community, and the impact of current theory on cross-cultural online community analyses. Recommendations in the areas of methodology, definition and theory are provided. These findings should be of interest to both specific online community researchers, and those in other multidisciplinary fields where online communities are being used as a research environment.     

Designing for Semantic Access: A Video Browsing System

Users of browsing applications often have vague information needs which can only be described in conceptual terms. Therefore, a video browsing system must accept conceptual queries for preselection and offer mechanisms for interactive inspection of the result set by the user. In this paper, we describe a MM-DBMS that we extended with the following components: Our retrieval engine calculates relevance values for the results of a conceptual query by feature aggregation on video shot granularity to offer conceptual, content-based access. To reduce startup delays within sessions, our admission control module admits only complete browsing sessions, if required resources, which are heuristically predicted from query results, are available. In addition, our intelligent client buffer strategy employs the retrieval relevance values to enable flexible user interactions during browsing.     

Randomized Controlled Trial for Behavioral Smoking and Weight Control Treatment: Effect of Concurrent Versus Sequential Intervention.

The authors compared simultaneous versus sequential approaches to multiple health behavior change in diet, exercise, and cigarette smoking. Female regular smokers (N = 315) randomized to 3 conditions received 16 weeks of behavioral smoking treatment, quit smoking at Week 5, and were followed for 9 months after quit date. Weight management was omitted for control and was added to the 1st 8 weeks for early diet (ED) and the final 8 weeks for late diet (LD). ED lacked lasting effect on weight gain, whereas LD initially lacked but gradually acquired a weight-suppression effect that stabilized (p = .004). Behavioral weight control did not undermine smoking cessation and, when initiated after the smoking quit date, slowed the rate of weight gain, supporting a sequential approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

eTeacher: Providing personalized assistance to e-learning students

In this paper we present eTeacher, an intelligent agent that provides personalized assistance to e-learning students. eTeacher observes a student’s behavior while he/she is taking online courses and automatically builds the student’s profile. This profile comprises the student’s learning style and information about the student’s performance, such as exercises done, topics studied, exam results. In our approach, a student’s learning style is automatically detected from the student’s actions in an e-learning system using Bayesian networks. Then, eTeacher uses the information contained in the student profile to proactively assist the student by suggesting him/her personalized courses of action that will help him/her during the learning process. eTeacher has been evaluated when assisting System Engineering students and the results obtained thus far are promising.