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In this paper, we develop themes from complexity and chaos theory that help to explain the technological change process. We apply two quantifiers, correlation dimensions and Lyapunov exponents, to examine the signs and degrees of chaotic technological dynamics. To illustrate our ideas, we study the development of electronic displays from 1976 to 2010, using patent data. The results of the chaos model are matched against the profiles of patent citations. Our analysis contributes to the development of a chaotic model of technological change.  相似文献   
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From a representative survey of 2,000 individuals, we study whether consumption of music through streaming services, like Spotify or YouTube, is a substitute or a complement to physical music consumption modes, such as CDs and live music. Controlling for the taste for music, various socio-demographic characteristics and the usual determinants of music consumption either offline (radio, TV, friends/relatives) or online (online recommendations, social networks), our results show that free music streaming (where the consumer does not possess the music but only has access to it) has no significant effect on CD sales and affects positively live music attendance, but only for national or international artists who are more likely to be available on streaming services.  相似文献   
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对21世纪我国高校网球热的预测   总被引:15,自引:0,他引:15  
网球运动历史悠久,是世界上开展得十分广泛且深受人们喜爱的一项体育运动。随着我国改革开放的深入,人民生活水平的提高,网球运动逐渐普及,以其固有的价值和魅力,受到大学生们的青睐,在21世纪我国高校将掀起网球热。本文较详细地阐述了掀起网球热的理由。  相似文献   
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This paper reports on how Maria (pseudonym), a non-native English speaker (NNES) and preservice teacher (PST) of English as an additional language (EAL), developed her professional identity during the practicum in an Australian secondary school. Drawing on activity theory, the study identified contradictions in Maria’s practicum activity and examined how Maria’s professional identity developed through her negotiation of the contradictions. Data included interviews with Maria before, during and after the practicum, her reflections, an interview with her school mentor (Ms Davies, pseudonym), and relevant documents. The findings reveal that Maria experienced contradictions between her multiple identities of NNES, student, becoming teacher, and classroom teacher, between her mentor’s teaching approach and that of her own, and between her practice and rules. The findings provide implications for researching teacher identity and supporting preservice EAL teachers in developing productive teacher identities during the practicum.  相似文献   
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This article is concerned with the control of a Semi-Active suspension system of a 7DOF Full Vehicle model, equipped with four Electro Rheological (ER) dampers, taking into account their incipient dissipativity constraints. Herein, a real-time, fast, advanced control structure is presented within the Model Predictive Control framework for Linear Parameter Varying (LPV) systems. The control algorithm is developed to provide a suitable trade-off between comfort and handling performances of the vehicle in a very limited sampling period (Ts=5ms), in view of a possible realtime implementation on a real vehicle. The control structure is tested and compared to other standard fast control approaches. Full nonlinear realistic simulation results illustrate the overall good operation and behaviour of the proposed control approach.  相似文献   
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This study examined the impact of parental involvement on adolescents' academic achievement in Korean families. The major strengths of the current research are the study of multiple dimensions of parental involvement, the longitudinal design and the consideration of mediating variables. Structural equation modelling was used to examine the direct and indirect effects of parental involvement on students' academic achievement using data from a nationally representative sample of middle school students from the Korea Youth Panel Survey. Results indicated: (1) parental involvement dimensions positively influenced achievement through its effects on student self‐concept and locus of control; and (2) parents' increased participation in involvement practices (monitoring, educational expectation and affection) increases students' self‐concept and locus of control.  相似文献   
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As advances in microfluidics continue to make contributions to diagnostics and life sciences, broader awareness of this expanding field becomes necessary. By leveraging low-cost microfabrication techniques that require no capital equipment or infrastructure, simple, accessible, and effective educational modules can be made available for a broad range of educational needs from middle school demonstrations to college laboratory classes. These modules demonstrate key microfluidic concepts such as diffusion and separation as well as "laboratory on-chip" applications including chemical reactions and biological assays. These modules are intended to provide an interdisciplinary hands-on experience, including chip design, fabrication of functional devices, and experiments at the microscale. Consequently, students will be able to conceptualize physics at small scales, gain experience in computer-aided design and microfabrication, and perform experiments-all in the context of addressing real-world challenges by making their own lab-on-chip devices.  相似文献   
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We present a microfluidic approach to characterizing temperature-dependent biomolecular interactions. Solvated L-arginine vasopressin (AVP) and its immobilized RNA aptamer (spiegelmer) were allowed to achieve equilibrium binding in a microchip at a series of selected temperatures. Unbound AVP were collected and analyzed with matrix-assisted laser desorption∕ionization mass spectrometry (MALDI-MS), yielding melting curves that reveal highly temperature-dependent zones in which affinity binding (36–45 °C) or dissociation (25–33 °C and 50–65 °C) occurs. Additionally, temperature-dependent binding isotherms were constructed; from these, thermodynamic quantities involved in binding were extracted. The results illustrated a strong change in heat capacity of interaction for this system, suggesting a considerable thermodynamic influence controlling vasopressin-spiegelmer interaction.  相似文献   
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