Purchasing power parity in G-7 countries: Further evidence based on ADL test for threshold cointegration

This study applies a newly-developed Autoregressive Distributed Lag (ADL) test for threshold cointegration, proposed by Li and Lee (2010) to test the validity of long-run purchasing power parity (PPP) for G-7 countries over the January 1994 to April 2010. The empirical results indicate that PPP only holds true for Canada and France two countries. Our results have important policy implications for the G-7 countries under study.Purchasing Power Parity; G-7 Countries; ADL Test; Threshold Cointegration

Molecular Ecology of Free-Living Chemoautotrophic Microbial Communities at a Shallow-sea Hydrothermal Vent

Deep-sea hydrothermal systems are unique habitats for microbial life with primary production based on chemosynthesis. They are considered to be windows to the subsurface biosphere. Their far more accessible shallow-sea counterparts are valuable targets to study the effects of hydrothermal activity on geology, seawater chemistry and microorganisms. Such an area of shallow-sea hydrothermal venting is observed approximately 2.5 km east off Panarea Island (Sicily, Italy). This system is characterized by fluid temperatures of up to 135°C, gas emissions dominated by CO2 and precipitation of elemental sulfur on the seafloor. It is quite well studied, yet, only very few studies exist on its microbial ecology. This thesis is therefore targeting the microbiology of sediment cores as part of an interdisciplinary project which combines geological, geochemical, biomarker and molecular biological investigations. It was intended to correlate the environmental parameters with the taxonomic composition and the metagenomes of the microbial community thereby gaining insights into the interaction of geosphere and biosphere. All samples were taken at Hot Lake, an oval-shaped (~10 by 6 meters) shallow (~2.5 m deep) depression at 18 m below sea level. The sediments in this depression are strongly affected by hydrothermal activity. In situ temperatures at 10 cm below sea floor of 36°C and 74°C were measured at two different sites within Hot Lake. Based on the physico-chemical parameters, a thermodynamic modeling was performed which revealed sulfur oxidation and sulfur reduction to be exergonic at Hot Lake. Microbial community structures of different sediment layers were first screened by automated rRNA intergenic spacer analysis (ARISA). Based on the ARISA fingerprints, a total of eight bacterial and archaeal 16S rRNA gene libraries were constructed from surface to bottom layers of sediments to gain more insights into microbial diversity. Comparative sequence analyses revealed a dominance of sequences affiliated with Epsilonproteobacteria, Deltaproteobacteria and Bacteroidetes. In the surface sediments, sequences close to anoxygenic phototrophic Chlorobi were also detected. In the bottom sediments, thermophilic bacteria such as Thermodesulfobacteria spp. were found. Hyperthermophilic Archaea sequences related to Desulfurococcaceae and Korarchaeota were retrieved from 74°C hot sediment. Based on the most closely related cultured representatives, it could be deduced that the majority of microorganisms in Hot Lake sediments have a sulfur-dependent metabolism, including sulfide oxidation, sulfur reduction or sulfate reduction. Fluorescence in situ hybridization showed the dominance of Bacteria in all depths of sediments. With increasing depth and temperature, the abundance of Archaea increased relatively to that of Bacteria. Metagenomic analyses revealed that Epsilonproteobacteria were dominating surface sediments of Hot Lake where they gain energy from sulfur metabolism to fix CO2 by the reductive tricarboxylic acid (rTCA) cycle. This is consistent with findings reported from deep-sea hydrothermal vent systems. The results have led to the conclusion that mixing between hydrothermal fluids and seawater results in distinctly different temperature gradients and ecological niches in Hot Lake sediments. Overall, the correlation of geochemical profiles, IPL analyses, characterization of the microbiological community and metagenomic analyses provided strong evidence for a sulfur-dominated metabolism in the surface sediments of Hot Lake

Exploring Taiwanese Students’ Perceptions of Active Explicit Vocabulary Instruction: A Case Study in an English Medium Course

Vocabulary knowledge is considered important in second and foreign language learning because learners’ insufficient vocabulary has been consistently reported as a significant problem in their achievement of second-language (L2) learning. Despite of numerous vocabulary studies, few of them have implemented a learner-centered and interactive approach. The current study attempted to implement an interactive explicit vocabulary instruction in an English-medium course in Taiwan. Students’ attitudes and perceptions on the implementation were explored. Data were collected using both quantitative and qualitative methods via questionnaires and interviews. Fifty-six students participated in this study. The results showed that students had positive attitudes toward this approach. In addition, students’ interview feedback demonstrated the most and least appreciated aspects of this approach. Educational and pedagogical suggestions for English-as-a-Foreign-Language (EFL) teachers were given

Situated Learning: Learn to Tell English Stories

For students in a perspective English teacher program, enhancing language proficiency and teaching knowledge is essential so that they can participate in the teaching community. This study investigated the acquisition of an unfamiliar discursive practice by four undergraduate students in a perspective EFL teacher training program. The practice is storytelling which is often overlooked in teacher-training programs in the English as a Foreign Language (EFL) context such as in Taiwan. In this study, four undergraduate students in a teacher-training program of a medium-sized university in southern Taiwan were provided an opportunity to tell stories to primary-school children. Qualitative data were collected, including students’ teaching experiences and reflective journals throughout the entire project, videotapes of four storytelling rehearsals and the real storytelling episodes, and interviews. By using situated learning as the theoretical framework, this study depicts the change in the students and instructor as well as in the students’ co-participation patterns by which the students moved from peripheral to fuller participation. This study provides EFL teacher educators a perspective that considers teacher training as co-constructed development in situated discursive practices

Ignition and Front Propagation in Polymer Electrolyte Membrane Fuel Cells

Water produced in a Polymer Electrolyte Membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Using a segmented anode fuel cell we study the effect of gas phase convection and membrane diffusion of water on the spatiotemporal nonlinear dynamics - localized ignition and front propagation - in the cell. Co-current gas flow causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate to the inlet; counter-current flow causes ignition in the interior of the cell, with the fronts subsequently spreading towards both inlets. These instabilities critically affect fuel cell performance