Language learners' perceptions of having two interactional contexts in eTandem

The aim of this study was to gain insights into how language learners perceive two online interactional contexts and how these perceptions impact the learners’ participation in eTandem learning. This study incorporated pair work with group discussion as interactional contexts, connecting Korean language learners with English language learners. Pair work included online chatting and personal blog writing where each pair exchanged feedback on one another’s L2 writing. Group discussion included interaction among all the participants in a group blog where they discussed weekly topics. The study found that individual participants differently perceived the effectiveness of the two interactional contexts: some thought that both contexts were helpful together for developing L2 skills and for acquiring cultural knowledge, while others thought that these two contexts together were not as effective as expected. These perceptions affected not only the participant’s own participation in the project, but also others’ participation. This study offers pedagogical implications for ways in which researchers can further improve the design of eTandem learning

VEHICLE SECURING SAFETY ASSESSMENTS OF A KOREAN COASTAL CAR FERRY ACCORDING TO ACCELERATION PREDICTION APPROACHES

The capsize and subsequent sinking of a coastal car ferry occurred along the Korean coast, resulting in hundreds of casualties. The rapid course change of the ship might have forced improperly secured cargoes to rush to one side and accelerated the capsizing event. This paper provides a comparative study of vehicle securing safety assessments composed of evaluations of the external inertia forces and lashing strengths for a car and a truck. The external inertia forces were evaluated based on the IMO CSS (CSS approach) and rule-based maximum motion angles (RULE approach). Being a car ferry as a target ship, the sea states were collected along the most frequent seagoing routes of the target ship. Frequency domain seakeeping analyses (FSA approach) were carried out and then the long-term motion components were derived using the collected sea state data. The long-term motion components were put forward based on time domain seakeeping analyses (TSA approach). The TSA approach estimated the most optimistic external forces, while the CSS approach provided the most conservative external forces. Assuming the vehicles were secured symmetrically with four steel wires, the lashing strengths were derived. More numbers of lashing cables were required for the heavy vehicles when the CSS approach was applied, while other approaches predicted sufficient lashing strengths compared to exerted forces

Contextual Linear Bandits under Noisy Features: Towards Bayesian Oracles

We study contextual linear bandit problems under uncertainty on features; they are noisy with missing entries. To address the challenges from the noise, we analyze Bayesian oracles given observed noisy features. Our Bayesian analysis finds that the optimal hypothesis can be far from the underlying realizability function, depending on noise characteristics, which is highly non-intuitive and does not occur for classical noiseless setups. This implies that classical approaches cannot guarantee a non-trivial regret bound. We thus propose an algorithm aiming at the Bayesian oracle from observed information under this model, achieving $\tilde{O}(d\sqrt{T})$ regret bound with respect to feature dimension $d$ and time horizon $T$. We demonstrate the proposed algorithm using synthetic and real-world datasets.Comment: 30 page

Exchange Rate Misalignments and World Imbalances: a FEER Approach for Emerging Countries

International audienceSince the mid-1990s, the world imbalances have increased significantly with a large US current deficit facing Asian surpluses, mainly Chinese. Since 2007, a partial reduction of these imbalances has been obtained, largely thanks to production's decreases, without large exchange rate adjustments. The Asian surpluses have remained important. The objective of this paper is to examine the exchange rate misalignments (ERM) of the main emerging countries in Asia and Latin America since the 1980s, so as to shed light on the 2000s by a long term analysis and compare with the industrialized countries' case. Our results confirm that ERM have been reduced since the mid-2000s at the world level, but the dollar remained overvalued against the East Asian countries, except the yen. Chinese, Indian and Brazilian exchange rate policies have been much contrasted since the 1980s. The Indian rupee has been more often overvalued while a more balance situation prevailed in Brazil only since the 2000s. The Latin American countries have faced wider and more dispersed ERM and current imbalances than East Asian countries. But Argentina, Chile and Uruguay benefits now of undervalued currencies while Mexico is closer to equilibrium