Characterization of a-Si:H/SiN multilayer waveguide polarization using an optical pumping application—LED

This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode （LED） pumping lights to its surface. By using double tubed coaxial line （DTCL） microwave plasma chemical vapor deposition （MPCVD） equipment, an a-Si：H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer order. The main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon nitrate. Once the sample was ready, another major objective of the experiment was to analyze the polarization characteristics of the fabricated waveguide. The idea of the experiment was to analyze how the waveguide reacts when three types of LED （blue, yellow, and red） are radiated onto its surface. The results showed that the fabrication of the a-Si：H/SiN sample is successful. Most effective transmission results, which accord with the polarization characteristics analysis, were obtained.     

Speaker adapted dynamic lexicons containing phonetic deviations of words

Speaker variability is an important source of speech variations which makes continuous speech recognition a difficult task. Adapting automatic speech recognition （ASR） models to the speaker variations is a well-known strategy to cope with the challenge, Almost all such techniques focus on developing adaptation solutions within the acoustic models of the ASR systems. Although variations of the acoustic features constitute an important portion of the inter-speaker variations, they do not cover variations at the phonetic level. Phonetic variations are known to form an important part of variations which are influenced by both micro-segmental and suprasegmental factors. Inter-speaker phonetic variations are influenced by the structure and anatomy of a speaker＇s articulatory system and also his/her speaking style which is driven by many speaker background characteristics such as accent, gender, age, socioeconomic and educational class. The effect of inter-speaker variations in the feature space may cause explicit phone recognition errors. These errors can be compensated later by having appropriate pronunciation variants for the lexicon entries which consider likely phone misclassifications besides pronunciation. In this paper, we introduce speaker adaptive dynamic pronunciation models, which generate different lexicons for various speaker clusters and different ranges of speech rate. The models are hybrids of speaker adapted contextual rules and dynamic generalized decision trees, which take into account word phonological structures, rate of speech, unigram probabilities and stress to generate pronunciation variants of words. Employing the set of speaker adapted dynamic lexicons in a Farsi （Persian） continuous speech recognition task results in word error rate reductions of as much as 10.1% in a speaker-dependent scenario and 7.4% in a speaker-independent scenario.     

To be or not to be in social media: How brand loyalty is affected by social media?

There is an ongoing debate over the activities of brands and companies in social media. Some researchers believe social media provide a unique opportunity for brands to foster their relationships with customers, while others believe the contrary. Taking the perspective of the brand community building plus the brand trust and loyalty literatures, our goal is to show how brand communities based on social media influence elements of the customer centric model (i.e., the relationships among focal customer and brand, product, company, and other customers) and brand loyalty. A survey-based empirical study with 441 respondents was conducted. The results of structural equation modeling show that brand communities established on social media have positive effects on customer/product, customer/brand, customer/company and customer/other customers relationships, which in turn have positive effects on brand trust, and trust has positive effects on brand loyalty. We find that brand trust has a fully mediating role in converting the effects of enhanced relationships in brand community to brand loyalty. The implications for marketing practice and future research are discussed.     

Reference Ranges for Serum Total Cholesterol, HDL-Cholesterol, LDL-Cholesterol, and VLDL-Cholesterol and Triglycerides in Healthy Iranian Ahvaz Population

Cardiovascular diseases (CVD) are recognized as major mortality causes and imposes tremendously heavy socio-economic burden worldwide. A vast variety of risk factors have been introduced in the literature known to enhance the incidence of CVD, such as hyperlipidemia. Therefore in order to make an accurate clinical decision it is essential to have appropriate reference ranges for lipids and lipoprotein particles in a particular population. Healthy female (n = 601) and male (n = 617) cases were randomly selected according to certain exclusion criteria from individuals visiting the major University hospital clinics situated in different part of Ahvaz city, Iran, from June 2010 to December 2010. Fasting blood samples (10 ml) were collected and analyzed for total cholesterol, total triglyceride and HDL-C employing enzymatic assays of CHOD-PAP, GPO-PAP and homogenous methods respectively. The samples were obtained such to include the ethnic populations of Persian, Arab. Lore leaving in this city. The data were analyzed statistically by SPSS-18 software. The obtained results were analyzed then age ethnic-wise and reference ranges (mean ± 1SD) were calculated. Remarkable differences between the obtained results for our population with other nations were seen. Also ethnic difference for HDL-C among our cases was noted. The observed significant differences among different nations and ethnicities emphasizes the need for nation-specific, local reference ranges for lipids and lipoproteins particles, to be established.     

The role of cognitive style and its influence on proportional reasoning

It has been suggested that proportional reasoning tasks contain field effects. Field-dependent students are considered to be highly influenced by the structure of the perceptual field and lack an articulated conceptual framework. To test the hypothesis that there is a significant correlation between field independence and proportional reasoning tasks, a sample of science students were tested to determine performance in proportional reasoning and degree of field independence. It was found that even students who are normally capable of proportional reasoning can be misled by the presence of field effects. A significant correlation (r = 0.50; p = 0.001) was found between the test of field independence and the nine items of proportional reasoning. Educational implications are drawn.     

Structuring collaboration in mixed-ability groups to promote verbal interaction,learning, and motivation of average-ability students

Average-ability students often do not take full advantage of learning in mixed-ability groups because they hardly engage in the group interaction. This study examined whether structuring collaboration by group roles and ground rules for helping behavior might help overcome this participatory inequality. In a plant biology course, heterogeneously grouped fourth-grade boys (n=164) were randomly assigned to a structured collaboration condition or an unconstrained comparison condition. Results indicated positive effects of structured collaboration on average-ability students’ achievement, motivation, and contribution to the group interaction. Another positive result was that structuring collaboration did not lower the scores of the high and low-ability students on these measures.     

Exploring alternative approaches to methodology in educational research

The objective of this study is to provide in-service teachers an opportunity to become familiar with the controversial nature of progress in science (growth of knowledge) and its implications for research methodology in education. The study is based on 41 participants who had registered for a nine-week course on Methodology of Investigation in Education, as part of their Master’s degree program. The course is based on 20 readings drawing upon a history and philosophy of science perspective (positivism, constructivism, Popper, Kuhn, Lakatos) and its implications for educational research. Course activities included written reports, class room discussions based on participants’ presentations, and written exams. Based on the results obtained it was concluded that: (a) participants were able to understand the basic ideas of constructivist philosophy and its pedagogical implications; (b) the role of behavioural objectives in actual educational practice was questioned; (c) integration of qualitative and quantitative research methods was considered to be an alternative to the current debate about the replacement of one method by the other; (d) participants considered the dilemma of evaluating students based on what they have learned or what they should have learned, within the social constructivist framework and generally favoured the former; and (e) most of the participants were reluctant to accept constructivism as a form of positivism, a controversial thesis that is gaining support in the research literature. Given the importance of alternative approaches to growth and meaning of knowledge, it is important that teachers be aware of conflicting situations in the classroom that refer to: objectivity, scientific method, qualitative-quantitative methods, relationship between method and problem, evaluation, and a critical appreciation of constructivism.     

Balancing chemical equations: The role of developmental level and mental capacity

Why are some students able to learn to use the trial and error method to balance chemical equations while others are not? To test the hypothesis that formal reasoning is required to balance even simple one-step equations, while formal reasoning and a sufficiently large mental capacity are required to balance more complex many-step equations, a sample of science students was tested to determine level of intellectual development, mental capacity, and degree of field dependence/field independence. Students were then given classroom instruction in using trial and error to balance equations. As predicted, a posttest revealed significant correlations between developmental level and equation balancing ability for both simple and complex equations. Also, as predicted, mental capacity correlated significantly with complex equations but not with simple equations. Field dependence/field independence played no significant role in performance. Educational implications are drawn.     

Argumentation-Based Computer Supported Collaborative Learning (ABCSCL): A synthesis of 15 years of research

Learning to argue is an essential objective in education; and online environments have been found to support the sharing, constructing, and representing of arguments in multiple formats for what has been termed Argumentation-Based Computer Supported Collaborative Learning (ABCSCL). The purpose of this review is to give an overview of research in the field of ABCSCL and to synthesize the findings. For this review, 108 publications (89 empirical studies and 19 conceptual papers) on ABCSCL research dating from 1995 through 2011 were studied to highlight the foci of the past 15 years. Building on Biggs’ (2003) model, the ABCSCL publications were systematically categorized with respect to student prerequisites, learning environment, processes, and outcomes. Based on the quantitative and qualitative findings, this paper concludes that ABCSCL environments should be designed in a systematic way that takes the variety of specific conditions for learning into account. It also offers suggestions for educational practice and future research.     

Online discussion compensates for suboptimal timing of supportive information presentation in a digitally supported learning environment

This study used a sequential set-up to investigate the consecutive effects of timing of supportive information presentation (information before vs. information during the learning task clusters) in interactive digital learning materials (IDLMs) and type of collaboration (personal discussion vs. online discussion) in computer-supported collaborative learning (CSCL) on student knowledge construction. Students (N = 87) were first randomly assigned to the two information presentation conditions to work individually on a case-based assignment in IDLM. Students who received information during learning task clusters tended to show better results on knowledge construction than those who received information only before each cluster. The students within the two separate information presentation conditions were then randomly assigned to pairs to discuss the outcomes of their assignments under either the personal discussion or online discussion condition in CSCL. When supportive information had been presented before each learning task cluster, online discussion led to better results than personal discussion. When supportive information had been presented during the learning task clusters, however, the online and personal discussion conditions had no differential effect on knowledge construction. Online discussion in CSCL appeared to compensate for suboptimal timing of presentation of supportive information before the learning task clusters in IDLM.