Monolingual, Bilingual Dictionaries and Language Study

This paper tries to prove that, neither monolingual nor bilingual dictionary can, by themselves satisfy the needs of foreign language learners. Different stages of second language acquisition require different types of dictionaries, and they all have their own unique function in helping the learners to form a new language habit. This paper makes a review about present and past research and various scholarly points of views. For research approach, a quantitative method is adopted to investigate which kind of dictionary best meets the needs of students in different stages of foreign language acquisition. Finally, results and discussions are shown to conclude the investigation. Key words: monolingual dictionary, bilingual dictionary, language study Résumé: Le présent article tente de prouver que, ni le dictionnaire monolingue ni le dictionnaire bilingue ne peut satisfaire les besoins des apprenants de langues étrangères. Les différentes étapes de l’acquisition de la deuxième langue exigent de différents types de dictionnaires, et ils ont tous leur propre fonction pour aider les apprenants à former une nouvelle habitude langagière. Le présent article met en revue les recherches actuelles et passées ainsi que les points de vues académiques divers. Quant à l’approche de recherches, des méthodes quantitatives sont adoptées pour étudier quel type de dictionnaire répond le mieux aux besoins des étudiants dans les différentes phases de l’acquisition des langues étrangères. Finalement, on montre les résultats et les discussions pour conclure l’investigation. Mots-Clés: dictionnaire monolingue, dictionnaire bilingue, étude linguistique 摘要：本文試圖證明無論單語詞典還是雙語詞典都不能獨立地滿足語言學習的需求。不同階段的外語學習需要使用不同的詞典，它們在幫助學習者形成一種新的語言習慣過程中發揮著不同的作用。本文回顧了有關文獻和不同的研究觀點，採用定量和定性的方法來研究哪種詞典能滿足二語習得不同階段的學習要求，最後得出結論。 關鍵詞：單語詞典；雙語詞典；語言學

Blue Phosphorene Oxide: Strain-tunable Quantum Phase Transitions and Novel 2D Emergent Fermions

Tunable quantum phase transitions and novel emergent fermions in solid state materials are fascinating subjects of research. Here, we propose a new stable two-dimensional (2D) material, the blue phosphorene oxide (BPO), which exhibits both. Based on first-principles calculations, we show that its equilibrium state is a narrow-bandgap semiconductor with three bands at low energy. Remarkably, a moderate strain can drive a semiconductor-to-semimetal quantum phase transition in BPO. At the critical transition point, the three bands cross at a single point at Fermi level, around which the quasiparticles are a novel type of 2D pseudospin-1 fermions. Going beyond the transition, the system becomes a symmetry-protected semimetal, for which the conduction and valence bands touch quadratically at a single Fermi point that is protected by symmetry, and the low-energy quasiparticles become another novel type of 2D double Weyl fermions. We construct effective models characterizing the phase transition and these novel emergent fermions, and we point out several exotic effects, including super Klein tunneling, supercollimation, and universal optical absorbance. Our result reveals BPO as an intriguing platform for the exploration of fundamental properties of quantum phase transitions and novel emergent fermions, and also suggests its great potential in nanoscale device applications.Comment: 23 pages, 5 figure

Regime switching in stochastic models of commodity prices: An application to an optimal tree harvesting problem

This paper investigates a regime switching model of stochastic lumber prices in the context of an optimal tree harvesting problem. Using lumber derivatives prices, two lumber price models are calibrated: a regime switching model and a single regime model. In the regime switching model, the lumber price can be in one of two regimes in which different mean reverting price processes prevail. An optimal tree harvesting problem is specified in terms of a linear complementarity problem which is solved using a fully implicit finite difference, fully-coupled, numerical approach. The land value and critical harvesting prices are found to be significantly different depending on which price model is used. The regime switching model shows promise as a parsimonious model of timber prices that can be incorporated into forestry investment problems.optimal tree harvesting, regime switching, calibration, lumber derivatives prices, fully implicit finite difference approach

Fundamental Conditions for N-th Order Accurate Lattice Boltzmann Models

In this paper, we theoretically prove a set of fundamental conditions pertaining discrete velocity sets and corresponding weights. These conditions provide sufficient conditions for a priori formulation of lattice Boltzmann models that automatically admit correct hydrodynamic moments up to any given N-th order

Anti-Hyperon polarization in high energy pp collisions with polarized beams

We study the longitudinal polarization of the Sigma_bar and Xi_bar anti-hyperons in polarized high energy pp collisions at large transverse momenta, extending a recent study for the Lambda_bar anti-hyperon. We make predictions by using different parametrizations of the polarized parton densities and models for the polarized fragmentation functions. Similar to the Lambda_bar polarization, the Xi_bar0 and Xi_bar+ polarizations are found to be sensitive to the polarized anti-strange sea in the nucleon. The Sigma_bar- and Sigma_bar+ polarizations show sensitivity to the light sea quark polarizations, \Delta \bar u(x) and \Delta \bar d(x), and their asymmetry.Comment: 17 pages, 9 figures,version to appear in PR