We construct and classify all groups given by triangular presentations associated to the smallest thick generalized quadrangle that act simply transitively on the vertices of hyperbolic triangular buildings of the smallest non-trivial thickness. Our classification yields 23 non-isomorphic torsion-free groups (which were obtained in an earlier work) and 168 non-isomorphic torsion groups acting on one of two possible buildings with the smallest thick generalized quadrangle as the link of each vertex. In analogy with the case, we find both torsion and torsion-free groups acting on the same building.

We study the equation a2−2b6=cp and its specialization a2−2=cp, where p is a prime, using the modular method. In particular, we use a ℚ-curve defined over for which the solution (a,b,c)=(±1,±1,−1) gives rise to a CM-form. This allows us to apply the modular method to resolve the equation a2−2b6=cp for p in certain congruence classes. For the specialization a2−2=cp, we use the multi-Frey technique of Siksek to obtain further refined results.

Over the past two decades, robots have been increasingly used in biomedical applications such as bone cutting. Traditional automated manufacturing processes are often unable to meet the safety and accuracy requirements for such applications, particularly for cutting inhomogeneous constitutions of bone. In this case, human–robot cooperation may prove to be an effective approach. In this paper, we demonstrate that a hybrid parallel manipulator under cooperative force control can achieve accurate bone cutting with sufficient safety guaranteed. First, a hybrid parallel manipulator was constructed to provide the required rigidity for bone cutting. Then a two-loop controller was designed to implement the human–robot cooperation in bone cutting. The position control loop of adaptive fuzzy control is responsible for achieving high-tracking performance by overcoming varying friction forces from the mechanism. The force control loop of the cooperative force control adjusts the feed rate of the cutter according to the bone slicing conditions and operator's supervisory commands. The experimental results show that the proposed controller can effectively achieve the required accuracy in bone cutting with required safety.

We introduce a robot–safety device system characterized by cold stand-by and by an admissible risky state. The system is attended by a single repairman and the robot has overall (break-in) priority in repair with regard to the safety device. We obtain an explicit formula for the point availability of the robot via an integral equation of the renewal-type. The explicit solution requires the notion of effective repair-versus-virtual repair. In order to decide whether the risky state is admissible, we also introduce a risk criterion. The criterion is always satisfied in the case of fast repair. As an example, we consider the case of Weibull–Gnedenko repair and we display a computer-plotted graph of the point availability obtained by a direct numerical solution of a convolution-type integral equation.

In this paper, we carry out stochastic comparisons of largest order statistics from multiple-outlier exponential models according to the likelihood ratio order (reversed hazard rate order) and the hazard rate order (usual stochastic order). It is proved, among others, that the weak majorization order between the two hazard rate vectors is equivalent to the likelihood ratio order (reversed hazard rate order) between largest order statistics, and that the p-larger order between the two hazard rate vectors is equivalent to the hazard rate order (usual stochastic order) between largest order statistics. We also extend these results to the proportional hazard rate models. The results established here strengthen and generalize some of the results known in the literature.

This study aims to explore the impact of different captions on second language (L2) learning in a computer-assisted multimedia context. A quasi-experimental design was adopted, and a total of thirty-two eighth graders selected from a junior high school joined the study. They were systematically assigned into four groups based on their proficiency in English; these groups were shown animations with English narration and one of the following types of caption: no captions (M1), Chinese captions (M2), English captions (M3), and Chinese plus English captions (M4). A multimedia English learning program was conducted; the learning content involved two scientific articles presented on a computer. To track the learning process, data on oral repetition were collected after each sentence or scene was played. A post-test evaluation and a semi-structured interview were conducted immediately after viewing. The results show that the effect of different captions in multimedia L2 learning with respect to vocabulary acquisition and reading comprehension depend on students’ L2 proficiency. With English and Chinese + English captions, learners with low proficiency performed better in learning English relative to those who did not have such captions. Students relied on graphics and animation as an important tool for understanding English sentences.

This paper illustrates how a freely available online corpus has been exploited in a module on teaching business letters covering the following four speech acts (functions) commonly found in business letters: invitations, requests, complaints and refusals. It is proposed that different strategies are required for teaching potentially non-face-threatening (invitations, requests) and face-threatening (complaints, refusals) speech acts.

The hands-on pedagogic activities follow the ‘guided inductive approach’ advocated by Johansson (2009) and draw on practices and strategies covered in the literature on using corpora in language learning and teaching, viz. the need for ‘pedagogic mediation’, and the ‘noticing’ hypothesis from second language acquisition studies.

This article discusses the informal learning of English by non-native speakers with particular reference to the role of virtual communities. The concept of informal learning is presented and related to current areas of interest in the literature such as incidental learning, and dynamic systems theory. Our research investigates how non-specialist language learners use the Internet in their spare time to read and listen to English, and also communicate in English, notably in online communities through social networking websites. The study looks particularly at the dynamics of these phenomena by studying a small number of non-native users of English over a period of two months. The results of this research will be used to question the relevance of the learner autonomy paradigm, which has been a cornerstone of language learning policy in Europe for the past thirty years.

This paper reports a project in which researchers at universities in Japan explored the use of Mobile Assisted Language Learning (MALL) practices by developing a learning module intended to help improve students’ scores on the TOEIC Listening and Reading Tests. MALL practices are currently being developed at universities in Japan because almost all students have mobile phones, many of them have had informal learning experiences with mobile devices, and students are integrating the communication and information gathering capabilities of mobile technology into their own lifestyles. The private nature of mobile phone communication may create barriers when students are asked to use personal mobile phones for school-centered learning activities. In this study a Nintendo DS mobile was used because it was affordable and students were familiar with this device for game playing and learning activities. In addition, because this device does not have the same telephone, messaging, and Internet functions that have made mobile phones an integral part of students’ private lives, a device such as the Nintendo DS may be a neutral mobile platform for the development of MALL activities which could later be adapted and transferred for use on private mobile phones. The primary aim of this study was to discover whether certain MALL practices would foster an advanced form of self-study, self-regulated learning (SRL). In SRL students take responsibility for arousing and sustaining their own motivation in order to make, carry out, and evaluate strategic learning plans. It was concluded that the use of the MALL learning module encouraged study without teacher intervention, i.e., self study, in terms of time spent on learning tasks, levels of satisfaction derived from the tasks, and self-measured achievement. Furthermore, SRL was observed in terms of the specificity of the goals, the customized creation of learning tasks and their in-class applications.

In most conventional settings, the events caused by an external shock are initiated at the moments of its occurrence. In this paper, we study the new classes of shock models: (i) When each shock from a nonhomogeneous Poisson processes can trigger a failure of a system not immediately, as in classical extreme shock models, but with delay of some random time. (ii) When each shock from a nonhomogeneous Poisson processes results not in an ‘immediate’ increment of wear, as in classical accumulated wear models, but triggers its own increasing wear process. The wear from different shocks is accumulated and the failure of a system occurs when it reaches a given boundary. We derive the corresponding survival and failure rate functions. Furthermore, we study the limiting behavior of the failure rate function where it is applicable.

We study a multi-item two-stage production system subject to Markov-modulated demands and production quantity requirements. The demand distribution for each item in each period is governed by a discrete Markov chain. The products are manufactured in two stages. In the first stage, a common intermediate product is manufactured, followed by product differentiation in the second stage. Lower and upper production limits, also known as production smoothing constraints, are imposed on both stages for all items. We propose a close-to-optimal heuristic to manage this system. To do so, we develop a lower bound problem and show that a state-dependent, modified base-stock policy is optimal. We also show when and why the heuristic works well. In our numerical study, the average optimality gap was 4.34%. We also establish some monotonicity results for policy parameters with respect to the production environment. Using these results and our numerical observations, we investigate the joint effect of (i) the two-stage production process, (ii) the production flexibility, and (iii) the fluctuating demand environment on the system's performance. For example, we quantify the value of flexible production as well as the effect of smoothing constraints on the benefits of postponement. We show that a redesign of the production process to allow for delayed product differentiation is more effective and valuable when it is accompanied by an investment in production flexibility.

The introduction of virtual learning environments has made new tools available that have the potential to support learner communication and interaction, thus aiding second language acquisition both from a psycholinguistic and a sociocultural point of view. This article focuses on the use of videoconferencing in the context of a larger exploratory study to find out how interaction was influenced by the affordances of the environment. Taking a mainly qualitative approach, the authors analysed the written and spoken interaction in recorded videoconferencing sessions, alongside examining some quantitative data to reveal participation patterns. Exploring language learning interaction in a synchronous online medium allows us to show how this is a process mediated by interaction with experts and peers as well as by the artefacts used (e.g., technology) and how learners use and combine multiple modes to make meaning. Our findings illustrate how an online videoconferencing environment with its multiple modalities can be used in language teaching, how teachers and learners adapt to the multimodal online environment and how new patterns of communication emerge in the process.

Stochastic comparisons of linear (circular) consecutive k-out-of-n:F systems with independent components are studied. A sufficient condition is given under which the lifetime of a circular consecutive k-out-of-n:F system with independent and nonidentically distributed components is stochastically decreasing in n for fixed k. Furthermore, the likelihood ratio orderings of the lifetimes of linear (circular) consecutive k-out-of-n:F systems with independent and identically distributed components are also established, and some counterexamples are given to show that these orderings are not true in general.

Presenting a persuasive authorial stance is a major challenge for second language (L2) writers in writing academic research. Failure to present an effective authorial stance often results in poor evaluation, which compromises a writer's research potential. This study proposes a “textlinguistic” approach to advanced academic writing to complement a typical corpus approach that is oriented toward exploring lexico-grammatical patterns at the sentence level. A web-based stance corpus was developed which allowed the users to study both the linguistic realizations of stance at clause/sentence level and how stance meanings are made at the rhetorical move level. The assumptions the study tested included: (1) whether a textlinguistic approach assists L2 writers to polish their research argument particularly as a result of improved stance deployment, and (2) whether the web-based corpus tool affords a constructivist environment which prompts the learners to infer linguistic patterns to attain deeper understanding. Seven L2 doctoral students in the social sciences were recruited. The results indicate a positive relationship between writing performance and more accurate use of stance. However, the application of higher order cognitive skills (e.g., inferring and verifying) was infrequent in the corpus environment. Instead, the writers used more lower-level cognitive skills (e.g., making sense and exploring) to learn. The participants accessed the integrated “context examples” most frequently to guide their learning, followed by rhetorical “move examples” and clause-based “stance examples”. This suggests that the learning of stance is critically contingent on the surrounding contexts. Overall, the study reveals that effective authorial stance-taking plays a critical role in effective academic argument. To better assist L2 academic writers, incorporating more (con)textual examples in computer corpora tools is recommended.

This paper describes techniques to characterize the number of singletons in the setting of the generalized birthday problem, that is, the birthday problem in which the birthdays are non-uniformly distributed over the year. Approximations for the mean and variance presented which explicitly indicate the impact of the heterogeneity (expressed in terms of the Kullback–Leibler distance with respect to the homogeneous distribution). Then an iterative scheme is presented for determining the distribution of the number of singletons. The approximations are validated by experiments with demographic data.