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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Watching the signs : an examination of foreign/second language written corrective feedback

Leeman, Paul Eric 02 October 2014 (has links)
This report seeks to examine the literature related to written corrective feedback in second/foreign language classrooms in order to inform the most effective pedagogical practices related to this topic. I begin with an article by Truscott which would set the tone for the academic debate on whether or not to provide written corrective feedback in L2 classrooms. In his 1996 article Truscott claims that written corrective feedback a) is not helpful, b) is harmful, and c) should be eliminated entirely. Chapter 1 covers this debate, referred to as the Truscott Debate, reviewing the many articles that directly answer the challenge laid down by Truscott (1996). Following a review of this academic debate, I examine the literature that investigates the specific providers of feedback (teachers or peer feedback), the types of feedback (direct or indirect) and the degree of focus related to those feedback options. Chapter 4 reviews other factors that can also affect the efficacy of written corrective feedback, such as student motivation, learner levels, and oral feedback in conjunction with written feedback and online feedback. Chapter 5 puts forth particular circumstances in which each type of feedback can be efficacious, offering a guide for the provision of feedback in a variety of circumstances. / text
92

Adolescents' L2 speaking anxiety : review of the literature and implications

Lee, Jeonghyun 07 October 2014 (has links)
This report addresses the importance of discussing adolescent learners in regard with their anxiety about foreign or second language (L2) speaking performance. To find implications on how to help adolescents reduce or overcome speaking anxiety in the language classroom, the report reviews extensive literature on 1) the distinct adolescent features that contribute to the development of shyness and communication apprehension; 2) the concept, component sources, and impacts of foreign language learning anxiety; and 3) the causes and effects of L2 speaking anxiety in language learning situations. Based on the review, the report provides implications from studies about language teaching and learning practices to alleviate L2 learning and speaking anxiety. These suggestions focus on meeting adolescents' needs in terms of 1) improving self-esteem, 2) developing coping skills about anxiety, and 3) facilitating a safer and more supportive classroom environment. / text
93

Le Lexique Mental L2: Connexions et Associations

Boulton, Alex 15 December 1998 (has links) (PDF)
Les modèles connexionistes de traitement en parallèle se sont inspirés de nos connaissances actuelles du cerveau humain. Selon ces modèles, les unités lexicales sont représentées dans l'esprit sous forme d'entrées liées dans un vaste réseau de connexions ; il s'agit d'un système adaptif très complexe qui permet un traitement extrêmement rapide et performant. Les connexions elles-mêmes doivent leur existence aux informations stockées à l'intérieur de chaque entrée lexicale : tout trait qui est partagé par deux ou plusieurs entrées peut susciter une connexion. L'apprenant possède dans son esprit des connaissances lexicales de deux langues à la fois, et la nature des connexions interlinguistiques s'avère cruciale pour tout modèle du lexique mental L2. Les nombreuses possibilités de connexions entre les deux lexiques sont alors étudiées en détail. Le modèle présenté est appuyé par des expériences d'associations lexicales interlinguistiques - une source précieuse (mais indirecte et donc souvent négligée) de données lors du développement d'un modèle connexioniste du lexique mental L2.
94

Vocabulary acquisition and the second language learner

Alf, Kerstin, starck, erik January 2010 (has links)
<p>Abstract</p><p>It is unclear how L2 students acquire vocabulary – how is it taught – or wheather it can even be taught. In an SSL (Swedish as second language) program for young adults the ambition has been to integrate the L2 students’ into the national high school (gymnasium) courses as quickly as possible, in order to meet the students’ demands for subject education and to challenge them on an appropriate knowledge level. Teachers noticed quite early that the course – integrated L2 students seemed to have a deeper understanding of words and an easier flow in their speech. The study was conducted to map and learn more about the differences in vocabulary with L2 students who were integrated in the national L1 programs in several subjects and L2 students who have chosen to focus, in an isolated group, on SSL only. How does the students’ vocabulary evolve in relation to time? The study is based on the vocabulary knowledge scale as the methodological tool and Stephen Krashen’s monitor model as the theoretical practice, and in particular the input hypothesis and the hypothesis of acquisition and learning in combination with Pauline Gibbons’s methodologies in scaffolding. In the study the test results of eight SSL students are compared; four of the students have chosen to integrate with the L1 classes and four of them have chosen not to integrate with the L1 students. We will show that students that participate in national “high school” courses on the same premises as the L1 students will, through exposure to vocabulary in text books, lectures and post scaffolding, learn their vocabulary at a faster and higher rate than students who focus on the structural functions and, often non-contextual, vocabulary training alone.</p><p> </p><p> </p><p> </p>
95

Word Frequency Effects in L2 Speakers: An ERP Study

Famoyegun, Akinjide January 2012 (has links)
The brain's neural responses to words of different frequencies provide information on lexical organization and the cognitive processes involved in word identification and retrieval of meaning. Monolingual research has shown that exposure to high frequency words yields less cognitive difficulty than low frequency words as demonstrated by smaller N400 waves within even-related potential (ERP) methodology. The purpose of the present study was to compare frequency effects in adult native (L1) and non-native (L2) speakers of English during a sentence reading task embedded with high and low frequency word-pairs. Both L1 and L2 groups produced N400 waves of larger amplitudes for high frequency words compared to low frequency words that peaked around the 400 ms time mark. Group comparison found no significant difference in N400 wave amplitude and peak latency between both groups. The results are discussed with respect to theories of L2 word learning and lexical organization.
96

Papillomavirus L2-Dependent Endocytosis and Subcellular Trafficking

Lu, Mingfeng, Lu, Mingfeng January 2016 (has links)
Human papillomaviruses (HPV) are among the most common sexually transmitted infections and are responsible for 5% of all human cancers. HPV type 16 is the most prevalent of the high-risk HPVs (a subgroup of HPVs with potential to cause cancer), accounting for ~55% of HPV-associated cancers. HPV16 is a nonenveloped virus, composed of the major capsid protein L1, the minor capsid protein L2, and a circular double-stranded DNA genome (vDNA) condensed with human histones. HPV initially infects undifferentiated basal keratinocytes and viral replication is dependent on epithelial differentiation. Like many other DNA viruses, HPV must deliver its vDNA to the host cell nucleus to successfully replicate. Initial binding of HPV16 to host cells is through L1 interactions with cell surface heparan sulfate receptors. Shortly after virus binding, L2 is believed to undergo furin cleavage-dependent conformational changes, resulting in spanning of the protein across the local membrane and exposure of the central and C-terminal regions of L2 (which was lumenal and and inaccessible before furin cleavage) to the host cell cytosol. L2 is critical for transport of the L2/vDNA from endosomes to the trans-Golgi network (TGN). We hypothesize that furin-dependent early L2 spanning, through the direct binding and recruitment of cytosolic sorting factors, may contribute to viral endocytosis and subcellular retrograde trafficking (trafficking from endosomes to Golgi) of vDNA. We have developed a Tac receptor (CD25 or IL2 receptor, a transmembrane cell surface protein) chimera system to study L2-dependent endocytosis and trafficking. In this system the Tac ecto- and transmembrane domains are fused to the ~400 amino acid portion of L2 that is likely cytosolic upon L2 spanning. Through transient expression of Tac-L2 chimera we use anti-Tac ectodomain antibodies to label and track cell surface populations by immunofluorescence and confocal microscopy. We have also adopted this system to study endocytosis through a cell surface biotinylation approach. Both approaches suggest that L2 may enhance endocytosis and preliminary evidence suggests that the Tac-L2 chimera may recruit the cytosolic retromer complex (the host cytosolic factors help protein retrograde trafficking) to preferentially traffic to the TGN. Retromer-dependent trafficking of cargo from early endosomes to the TGN is known to involve certain members of the sorting nexin family, specifically the SNX-BAR proteins. We performed a small siRNA screen and identify SNX6 and SNX32 (aka SNX6b) as SNX-BAR proteins that may be specifically involved in retrograde trafficking of HPV16 L2/vDNA during infection. Future work will focus on the mechanisms through which L2 and SNX6 influence HPV16 entry and trafficking.
97

The Rise of Postmethod Epistemology in the L2 English Teaching Field

Alsuwat, Sami Eid 05 1900 (has links)
Citation analysis, which provides insights into the influence of particular scholarly work in a field of study, can also show epistemological "turns" through patterns of citations over time. This study explored the impact of postmethod epistemology on the shared knowledge of the English-as-a-second-language (L2) education community over a 26-year period. The approach consisted of tabulating and analyzing citations in 125 articles from two major journals, Teaching English to Speakers of Other Languages Quarterly (TESOL Qrtrly) and English Language Teaching Journal (ELT). The time period covered was 1994, when the term postmethod was introduced in TESOL Qrtrly, through 2019. Attention went to the following questions for each journal and for both journals together: (i) who is the most influential of the three major postmethod authors, B. Kumaravadivelu, Richard Allwright, or Hans Stern? (ii) what was the most cited postmethod publication? and (iii) have there been patterns over time for citations of postmethod authors and publications and for the use of the term postmethod? Of the three postmethod authors, Kumaravadivelu was the most cited in the two journals combined. For TESOL Qrtrly, Kumaravadivelu was the most cited, and Stern was second. For ELT, Kumaravadivelu and Allwright had an equal number of citations, and both surpassed Stern. Of the 23 postmethod publications by these scholars, the most highly cited in both journals was Kumaravadivelu's 1994 article "The Postmethod Condition." It was the most cited in TESOL Quarterly, followed by Stern's 1983 book Fundamental Concepts of Language Teaching. In ELT, Allwright and Bailey's 1991 book, Focus on the Language Classroom, was the most cited followed by Allwright's 2003 article, "Exploratory Practice: Rethinking Practitioner Research," published in Language Teaching Research. Trend analyses for citations in TESOL Quarterly and ELT showed curvilinear patterns with a peak in postmethod citations in the two journals in the mid-2000s. In regard to the term postmethod, patterns suggested that it did not become mainstream in the two journals that were studied. This inquiry, which was focused on two major journals in L2 English education, provided some details about the impact of postmethod epistemology in a period that some scholars have called the "postmethod era." Through citation analysis, the study helps to situate postmethod epistemology historically.
98

Kernel Methods for Collaborative Filtering

Sun, Xinyuan 25 January 2016 (has links)
The goal of the thesis is to extend the kernel methods to matrix factorization(MF) for collaborative ltering(CF). In current literature, MF methods usually assume that the correlated data is distributed on a linear hyperplane, which is not always the case. The best known member of kernel methods is support vector machine (SVM) on linearly non-separable data. In this thesis, we apply kernel methods on MF, embedding the data into a possibly higher dimensional space and conduct factorization in that space. To improve kernelized matrix factorization, we apply multi-kernel learning methods to select optimal kernel functions from the candidates and introduce L2-norm regularization on the weight learning process. In our empirical study, we conduct experiments on three real-world datasets. The results suggest that the proposed method can improve the accuracy of the prediction surpassing state-of-art CF methods.
99

Perceptual representations in Interlanguage Phonology : subcategorial learning in late-learners with a smaller vowel inventory

Barrientos Contreras, Fernanda January 2018 (has links)
In this thesis I explore the phonological nature of newly acquired perceptual representations by highly proficient late-learners of English whose L1 is Spanish, specifically in the case where two different L2 sounds are being initially mapped onto the same L1 category. I claim that these perceptual representations are not phonemic; rather, what these learners acquire are phonetic representations that can be discriminable under certain conditions in a manner similar to that of native speakers, but that are nevertheless identified as tokens of the same L1 category. Since speech perception is a categorisation process where the acoustic input is mapped onto the existing phonemic categories, then late-learners will use their L1 representations when perceiving acoustic input; and will therefore have no need to create new perceptual categories. An alternative hypothesis holds that late-learners can bootstrap new perceptual categories by means of UG access, which allows them to bypass the default categorisation process and notice the difference between their L1 categories and the actual L2 input, so that new perceptual categories can be created. This thesis focuses on the acquisition of the perceptual contrast between the open-mid back unrounded vowel /2/ and the low back unrounded vowel /A/, both of which are mapped onto the same L1 perceptual category /a/. Two experiments were conducted. Subjects were divided in three groups: one of native speakers (NS), a group of highly proficient nonnative speakers of English with Spanish as L1 (NNS-A), and a group of L1 Spanish speakers who were nonproficient in English (NNS-B). The experiments included identification, discrimination and rating tasks along synthesised /A - 2/ vowel continua (7-step and 5-step). The results showed that unlike the NS group, both groups of nonnative speakers categorised the tokens along the /2 - A/ continuum randomly when using L2-like labels; and showing a strong preference towards /a/ when using L1-like labels. Discrimination, on the other hand, differed according to the task: discrimination of adjacent tokens yielded similar results across the three groups, but nonadjacent tokens showed that the NNS-A group is more sensitive than the NNS-B group and less sensitive than the NS group. Finally, prototypicality ratings showed that while NS considered the endpoints of the continuum as good exemplars of the categories /A/ and /2/, both groups of nonnative speakers rated all tokens along the continuum as equally good instances of /a/. From these results I conclude that while late-learners of L2 English do not create new phonemic categories for /A/ and /2/, they are able to perceive a difference that nevertheless does not seem to be enough to create a category split. These findings have implications for a theory of learnability in SLA, since it suggests that latelearners have partial access to UG insofar as input alone leads to learning within the phonetic domain but not to creation of new phonemic categories.
100

Intelligent Control for distillation columns

Al-Dunainawi, Yousif Khalaf Yousif January 2017 (has links)
Nowadays, industrial processes are having to be rapidly developed to meet high standards regarding increases in the production rate and/or improving product quality. Fulfilling these requirements is having to work in tandem with the pressure to reduce energy consumption due to global environmental regulations. Consequently, most industrial processes critically rely on automatic control, which can provide efficient solutions to meet such challenges and prerequisites. For this thesis, an intelligent system design has been investigated for controlling the distillation process, which is characterised by highly nonlinear and dynamic behaviour. These features raise very challenging tasks for control systems designers. Fuzzy logic and artificial neural networks (ANNs) are the main methods used in this study to design different controllers, namely: PI- PD- and PID-like fuzzy controllers, ANN-based NARMAL2 in addition to a conventional PID controller for comparison purposes. Genetic algorithm (GA) and particle swarm optimisation (PSO) have also been utilised to tune fuzzy controllers by finding the best set of scaling factors. Finally, an intelligent controller is proposed, called ANFIS-based NARMA-L2, which uses ANFIS as an approximation approach for identifying the underlying systems in a NARMA-L2 configuration. The controllers are applied to control two compositions of a binary distillation column, which has been modelled and simulated in MATLAB® and on the Simulink® platform. Comparative analysis has been undertaken to investigate the controllers' performance, which shows that PID-like FLC outperforms the other tested fuzzy control configurations, i.e. PI- and PD-like. Moreover, PSO has been found to outperform GA in finding the best set of scaling factors and over a shorter time period. Subsequently, the performance of PID-like FLC has been compared with ANN-based NARMA-L2 and the proposed ANFIS-based NARMA-L2, by subjecting the controlled column to different test scenarios. Furthermore, the stability and robustness of the controllers have been assessed by subjecting the controlled column to inputs variance and disturbances situations. The proposed ANFIS-based NARMAL2 controller outperforms and demonstrates more tolerance of disturbances than the other controllers. Finally, the study has involved investigating the control of a multicomponent distillation column due to its significant enhancement in operational efficiency regarding energy saving and recent widespread implementation. That is, Kaibel's distillation column with 4×4 configuration has been simulated also in MATLAB® and on the Simulink® platform with the proposed controller being implemented to control the temperatures of the column and the outcomes subsequently compared with conventional PID controllers. Again, the novel controller has proven its superiority regarding the disturbances tolerance as well as dealing with the high dynamics and nonlinear behaviour.

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