475 research outputs found

    Chinese learners and computer assisted language learning: a study of learning styles, learner attitudes and the effectiveness of CALL in Chinese higher education

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    E-leaming has become a staple diet in many learners’ academic lives in higher education institutions all around the world. This study did not follow the techno- centric standpoint and the comparative research design tradition in this field; instead, it focused on how learners’ learning styles and attitudes interact with the effectiveness of E-leaming implementation in the field of foreign language learning. The research was set in the author’s home institution—a comprehensive university in mainland China, where the first- and second-year undergraduate students who were studying a compulsory English course were surveyed from 2003 to 2004. For this course, the College of Foreign Languages developed an online computer-assisted language learning (CALL) environment—NCE Online which was the basis of this investigation. The author’s former colleagues helped organise the distribution and collection of 4 questionnaires and 9 groups of student interviews over one academic year. A total of 5258 participants completed the first questionnaire in 2003 while the numbers of participants who completed the other questions varied from around 200 to 700. To understand data from the learners in more depth, the language teachers and NCE Online developers were also surveyed with a questionnaire and individual interviews. The results showed that the learners had very positive attitudes towards the use of computer technologies in their study, and that there was an evident tendency to expect an increasing proportion of CALL elements as the students progressed in their English study. Despite these positive attitudes, what was equally clear was that there were still more students who preferred to have traditional classroom learning as their main learning mode, and they did not think of the E- leaming materials available as more effective than the traditional ones. Meanwhile, their teachers’ attitudes and the University’s policies also played an important role in influencing learners’ attitudes and actual behaviour toward the CALL system. In addition, the research revealed that Chinese learners have learning styles distinct from their peers in the west, which suggests that a CALL environment for Chinese learners should not follow blindly the much-advocated constructivist design model in the west. Reconsideration of both the ideals of foreign language teaching methodologies and E-leaming pedagogies, which originated mainly in Europe and Northern America, needs to take place before the design of a CALL system for Chinese learners. The implications of this research were therefore discussed to begin just such a rethinking of CALL implementations in Chinese higher education

    Inhomogeneous parabolic equations on unbounded metric measure spaces

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    We study inhomogeneous semilinear parabolic equations with source term f independent of time u_{t}={\Delta}u+u^{p}+f(x) on a metric measure space, subject to the conditions that f(x)\geq 0 and u(0,x)=\phi(x)\geq 0. By establishing Harnack-type inequalities in time t and some powerful estimates, we give sufficient conditions for non-existence, local existence, and global existence of weak solutions. This paper generalizes previous results on Euclidean spaces to general metric measure spaces

    Channel selection in e-commerce age: a strategic analysis of co-op advertising models

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    Purpose: The purpose of this paper is to develop and compare two co-op advertising models: advertising model under traditional channel and co-op advertising model under dual channel, to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer. Design/methodology/approach: Stackelberg game theoretical is used to develop two co-op advertising models: co-op advertising model under traditional channel and co-op advertising model under dual channel. Then we compare the two models to select optimal channel structure to sell products for manufacturer and to derive optimal co-op advertising strategies for the manufacturer and the retailer. Furthermore, we analyze the impact of product web-fit on these optimal strategies and illustrate by some numeral examples. Based on our results, we provide some significant theories and managerial insights, and derive some probable paths of future research. Findings: We provide a framework for researching optimal co-op advertising strategies in a two-level supply chain considering different marketing channel structures. First, we discuss the traditional channel co-op adverting model and the dual channel co-op advertising model based on Stackelberg game theoretical, and we derive optimal co-op advertising strategies. Next, comparisons of these two channel structures are discussed and we find that the manufacturer always benefits from dual channel. But the retailer not always benefits from dual channel structure, and dual channel structure is better than retail channel with certain conditions. Also, the optimal co-op advertising strategies for the manufacturer and the retailer are obtained. Research limitations/implications: First, we focus on the aforementioned two channel structures; a further comparison with other channel structures can be investigated. Second, we ignore some factors that influence the demand of product, such as service and price. We can do some researches from the point of these factors. Third, how demand uncertainty affects the channel selection and co-op advertising strategy is another interesting research item. Practical implications: The manufacturer and the retailer know that the impact of co-op adverting on the demands of traditional channel and direct channel, both would like to choose reasonable strategies to improve the channel coordination. Therefore, it would be best if business managers conduct market survey before they start their co-op advertising campaign. Originality/value: Two new co-op advertising models in E-commerce age are developed, and the impact of product web-fit on these optimal strategies are analyzed and illustrate by some numeral examples. In addition, optimal channel structure in E-commerce age are selected for manufacturer and the retailerPeer Reviewe

    On the Narrative Features of British Sitcoms: Take The IT Crowd and Yes, Prime Minister as Examples

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    In recent years, British TV dramas have been a glaring phenomenon and the “new favorite” of fans who love watching overseas TV plays. This paper takes two TV dramas of The IT Crowd and Yes, Prime Minister for case studies, explores the narrative features of British sitcom from dramatic narrative tendency, core narration of “people”, self-deprecating humor, unity of conflict and social significance, concludes three points of inspiration for China’s film and television creation: “learn” instead of “imitate”, “serious” instead of “funny”, “modern” as well as “traditional.”

    Breeding response of transcript profiling in developing seeds of Brassica napus

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    <p>Abstract</p> <p>Background</p> <p>The upgrading of rapeseed cultivars has resulted in a substantial improvement in yield and quality in China over the past 30 years. With the selective pressure against fatty acid composition and oil content, high erucic acid- and low oil-content cultivars have been replaced by low erucic acid- and high oil-content cultivars. The high erucic acid cultivar Zhongyou 821 and its descendent, low erucic acid cultivar Zhongshuang 9, are representatives of two generations of the most outstanding Chinese rapeseed cultivars (<it>B. napus</it>) developed the past 2 decades. This paper compares the transcriptional profiles of Zhongshuang 9 and Zhongyou 821 for 32 genes that are principally involved in lipid biosynthesis during seed development in order to elucidate how the transcriptional profiles of these genes responded to quality improvement over the past 20 years.</p> <p>Results</p> <p>Comparison of the cultivar Zhongyou 821 with its descendent, Zhongshuang 9, shows that the transcriptional levels of seven of the 32 genes were upregulated by 30% to 109%, including <it>FAD3</it>, <it>ACCase, FAE1</it>, <it>GKTP</it>, <it>Caleosin</it>, <it>GAPDH</it>, and <it>PEPC</it>. Of the 32 genes, 10 (<it>KAS3, β-CT, BcRK6, P450, FatA, Oleosin, FAD6, FatB, α-CT </it>and <it>SUC1</it>) were downregulated by at least 20% and most by 50%. The <it>Napin </it>gene alone accounted for over 75% of total transcription from all 32 genes assessed in both cultivars. Most of the genes showed significant correlation with fatty acid accumulation, but the correlation in ZS9 was significantly different from that in ZY821. Higher <it>KCR2 </it>activity is associated with higher C16:0, C18:0, and C18:2 in both cultivars, lower C22:1 and total fatty acid content in ZY821, and lower 18:1 in ZS9.</p> <p>Conclusion</p> <p>This paper illustrates the response of the transcription levels of 32 genes to breeding in developing rapeseed seeds. Both cultivars showed similar transcription profiles, with the <it>Napin </it>gene predominantly transcribed. Selective pressure for zero erucic acid, low glucosinolate, high oleic acid and high oil content, as well as high yield, resulted in higher <it>FAD3</it>, <it>ACCase, FAE1</it>, <it>GKTP</it>, <it>Caleosin</it>, <it>GAPDH</it>, and <it>PEPC </it>expression levels and lower <it>KAS3, β-CT, BcRK6, P450, FatA, Oleosin, FAD6, FatB, α-CT </it>and <it>SUC1 </it>expression levels. It also resulted in altered relationships between these genes during storage accumulation in seed development.</p

    pH-sensitive core-shell nanoparticles for intracellular drug delivery

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Vita.Includes bibliographical references (p. 193-208).Therapeutics such as proteins, DNA, or siRNA, can only exert their function in the cell cytosol or nucleus. However, most of them are cell membrane impermeable molecules that can only be taken up by cells via endocytosis or phagocytosis. Such drug molecules are thus confined in endolysosomes, where reduced pH and degradative enzymes may destroy them without therapeutic gain. Efficient escape of drug molecules to the cytosol before destruction in endolysosomes is a major challenge for intracellular drug delivery. To address this issue, we designed a pH-sensitive core-shell nanoparticle to segregate the functions of the particle into an endosome-disrupting pH-responsive core that would absorb protons at endolysosomal pH, and a shell whose composition could be tuned to facilitate particle targeting, cell binding, and drug binding. Two-stage surfactant-free emulsion polymerization of 2-diethylamino ethyl methacrylate (DEAEMA) (core) and 2-amino ethyl methacrylate (AEMA) (shell) in the presence of a crosslinker was used for the synthesis of monodisperse core-shell hydrogel nanoparticles of 200 nm in diameter. The protonation of tertiary amine groups on the polyDEAEMA core on moving from extracellular to endolysosomal pH resulted in reversible swelling of the nanoparticles with a 2.8-fold diameter change. With the aid of pH-sensitivity of these nanoparticles, efficient cytosolic delivery of calcein (with ~95% efficiency) was achieved by disrupting endolysosomes via proton sponge effect. The primary amine rich shell was found to facilitate cell and drug binding, and provided negligible cytotoxicity by sequestering the proton sponge component from any direct interactions with cells. These particles demonstrated a useful means to deliver therapeutic molecules to the cytosol of cells of interest efficiently.(cont.) The applications of nanoparticles showed significant improvement in delivering a model antigen vaccine protein ovalbumin (OVA) to primary dendritic cells for T cell activation, and promising knockdown of mRNA by delivering siRNA to epithelial cells for gene silencing. To extend this approach to a fully biodegradable system, nanoparticles with a cleavable crosslinker bis (acryloyl) cystamine (BAC) were synthesized. Preliminary explorations of this approach showed that such particles can degrade in the presence of glutathione in vitro, a reducing peptide present at mM concentrations in the cytosol of mammalian cells. This design could potentially serve as a drug releasing mechanism to further improve delivery efficiency.by Yuhua Hu.Ph.D

    Facile preparation of antifouling nanofiltration membrane by grafting zwitterions for reuse of shale gas wastewater

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    Complex organic matter causes severe fouling when membranes are applied for shale gas wastewater (SGW) treatment. This study reports the grafting of a zwitterionic polymer brush consisting of poly (sulfobetaine methacrylate) (PSBMA) onto the surface of a commercial nanofiltration (NF) membrane via electron transferatom transfer radical polymerization (ARGET-ATRP) to achieve anti-fouling property, especially against organic foulants. Compared to the pristine NF membranes, the PSBMA-grafted NF membrane showed high performance when challenged by SGW as a feed stream: (1) The flux stability was significantly improved during long-term operation, with a 64.28% increase in flux normalization at 50% recovery rate of SGW, while maintaining a suitable initial flux and near constant ion removal rate; (2) Based on excitation-emission-matrix spectra integrated in the fluorescence region, the removal of protein-like organic matters and humus-like organic matters increased by 34% and 16.5%, respectively; (3) The XDLVO theory supports the hypothesis that the hydrophobic interactions between the membrane surface and organic foulants were reduced by enhancing the Lewis acid-base interaction energy. The proposed anti-fouling zwitterionic membranes has potential in industrial application for the on-site reuse of SGW

    Numerical Modeling of Mineralizing Processes During the Formation of the Yangzhuang Kiruna-Type Iron Deposit, Middle and Lower Yangtze River Metallogenic Belt, China: Implications for the Genesis and Longevity of Kiruna-Type Iron Oxide-Apatite Systems

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    The Yangzhuang iron deposit is a Kiruna-type iron oxide-apatite (IOA) deposit within the Ningwu mining district of the Middle and Lower Yangtze River Metallogenic Belt (MLYRMB), China. This study applies a numerical modeling approach to identify the key processes associated with the formation of the deposit that cannot be easily identified using traditional analytical approaches, including the duration of the mineralizing process and the genesis of iron orebodies within intrusions associated with the deposit. This approach highlights the practical value of numerical modeling in quantitatively analyzing mineralizing processes during the formation of mineral deposits and assesses how these methods can be used in future geological research. Our numerical model links heat transfer, pressure, fluid flow, chemical reactions, and the movement of ore-forming material. Results show that temperature anomaly and structure (occurrence of the contact of intrusion and the Triassic Xujiashan group) are two key factors controlling the formation of the Yangzhuang deposit. This modeling also indicates that the formation of the Yangzhuang deposit only took some 8000 years, a reaction that is likely to be controlled by temperature and diffusion rates within the system. The dynamic changes of temperature and the distribution of mineralization also indicate that the orebodies located inside the intrusions most likely formed after magma ascent rather than representing blocks of existing mineralization that descended into the magma as a result of stoping or other similar processes. All these data form the basis for future research into the forming processes of Kiruna-type IOA systems as well as magmatic–hydrothermal systems more broadly, including providing useful insights for future exploration for these systems. The simulation approach used in this study has several limitations, such as oversimplified chemical reactions, uncertainty of pre-metallogenic conditions and limitation of 2D model. Future development into both theories and methods will definitely improve the practical significance of numerical simulation of ore-forming processes and provide quantitative results for more geological issues
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