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601.
In a study of innovations developed by mountain bikers, we find that user-innovators almost always utilize “local” information - information already in their possession or generated by themselves - both to determine the need for and to develop the solutions for their innovations. We argue that this finding fits the economic incentives operating on users. Local need information will in general be the most relevant to user-innovators, since the bulk of their innovation-related rewards typically come from in-house use. User-innovators will increasingly tend to rely on local solution information as the stickiness of non-local solution information rises. When user-innovators do rely on local information, it may be possible to predict the general nature of the innovations they might develop. 相似文献
602.
Xiang Peng Weihao Wang Men Xia Hui Chen A R Ravishankara Qinyi Li Alfonso Saiz-Lopez Pengfei Liu Fei Zhang Chenglong Zhang Likun Xue Xinfeng Wang Christian George Jinhe Wang Yujing Mu Jianmin Chen Tao Wang 《国家科学评论(英文版)》2021,8(7):94-104
Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging at 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine and chlorine atoms. The halogen atoms increased the abundance of ‘conventional’ tropospheric oxidants (OH, HO2 and RO2) by 26%–73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent. 相似文献
603.
This paper addresses the question why socio-technical transitions follow similar trajectories in various parts of the world, even though the relevant material preconditions and institutional contexts vary greatly between different regions and countries. It takes a critical stance on the implicit methodological nationalism in transition studies’ socio-technical regime concept and proposes an alternative ‘global’ regime perspective that embraces the increasingly multi-scalar actor networks and institutional rationalities, which influence transition dynamics beyond national or regional borders. By drawing on globalization theories from sociology and human geography, we show that socio-technical systems often develop institutional rationalities that are diffused via international networks and thus become influential in various places around the world. In so doing, we shed light on the multi-scalar interrelatedness of institutional structures and actors in socio-technical systems and elaborate on the implications for the conceptualization of transition dynamics. The paper illustrates this with the case study of an unsuccessful transition in the Chinese wastewater sector. Recent studies indicate that key decisions on wastewater infrastructure expansion were not only influenced by path-dependencies stemming from China’s national context, but equally (or even more critically) by the dominant rationality of the water sector’s global socio-technical regime. We conclude by discussing the contours of a new research agenda around the notion of global socio-technical regimes. 相似文献
604.
Kang Kug Lee Toru Matsu-ura Andrew E. Rosselot Taylor R. Broda James M. Wells Christian I. Hong 《Biomicrofluidics》2021,15(1)
Perfused three-dimensional (3D) cultures enable long-term in situ growth and monitoring of 3D organoids making them well-suited for investigating organoid development, growth, and function. One of the limitations of this long-term on-chip perfused 3D culture is unintended and disruptive air bubbles. To overcome this obstacle, we invented an imaging platform that integrates an innovative microfluidic bubble pocket for long-term perfused 3D culture of gastrointestinal (GI) organoids. We successfully applied 3D printing technology to create polymer molds that cast polydimethylsiloxane (PDMS) culture chambers in addition to bubble pockets. Our developed platform traps unintended, or induced, air bubbles in an integrated PDMS pocket chamber, where the bubbles diffuse out across the gas permeable PDMS or an outlet tube. We demonstrated that our robust platform integrated with the novel bubble pocket effectively circumvents the development of bubbles into human and mouse GI organoid cultures during long-term perfused time-course imaging. Our platform with the innovative integrated bubble pocket is ideally suited for studies requiring long-term perfusion monitoring of organ growth and morphogenesis as well as function. 相似文献
605.
Why space matters in technological innovation systems—Mapping global knowledge dynamics of membrane bioreactor technology 总被引:1,自引:0,他引:1
Studies on technological innovation systems (TISs) often set spatial boundaries at the national level and treat supranational levels as a geographically undifferentiated and freely accessible global technological opportunity set. This article criticizes this conceptualization and proposes instead to analyze relevant actors, networks and processes in TIS from a relational perspective on space. It develops an analytical framework which allows investigating innovation processes (or ‘functions’) of a TIS at and across different spatial scales. Based on social network analysis of a co-publication dataset from membrane bioreactor technology, we illustrate how the spatial characteristics of collaborations in knowledge creation vary greatly over relatively short periods of time. This finding suggests that TIS studies should be more reflexive on system boundary setting both regarding the identification and analysis of core processes as well as in the formulation of policy advice. 相似文献
606.
Jean Slawinski Raphaël Dumas Laurence Cheze Guy Ontanon Christian Miller Alice Mazure–Bonnefoy 《Journal of sports sciences》2013,31(3):256-263
Abstract Few studies have focused on the effect of posture during sprint start. The aim of this study was to measure the effect of the modification of horizontal distance between the blocks during sprint start on three dimensional (3D) joint angular velocity. Nine trained sprinters started using three different starting positions (bunched, medium and elongated). They were equipped with 63 passive reflective markers, and an opto-electronic Motion Analysis® system was used to collect the 3D marker trajectories. During the pushing phase on the blocks, norm of the joint angular velocity (NJAV), 3D Euler angular velocity (EAV) and pushing time on the blocks were calculated. The results demonstrated that the decrease of the block spacing induces an opposite effect on the angular velocity of joints of the lower and the upper limbs. The NJAV of the upper limbs is greater in the bunched start, whereas the NJAV of the lower limbs is smaller. The modifications of NJAV were due to a combination of the movement of the joints in the different degrees of freedom. The medium start seems to be the best compromise because it leads, in a short pushing time, to a combination of optimal joint velocities for upper and lower segments. 相似文献
607.
Karen Christian 《International Journal of Science Education》2013,35(14):2231-2255
The central goal of the present exploratory study was to investigate the nature of the content-related interactions in study groups independently organized by college organic chemistry students. We were particularly interested in the identification of the different factors that affected the emergence of opportunities for students to co-construct understanding and engage in higher levels of cognitive processing. Our results are based on the analysis of in situ observations of 34 self-initiated study sessions involving over a 100 students in three academic semesters. The investigation revealed three major types of social regulation processes, teaching, tutoring, and co-construction in the observed study sessions. However, the extent to which students engaged in each of them varied widely from one session to another. This variability was mostly determined by the specific composition of the study groups and the nature of the study tasks in which they were engaged. Decisions about how to organize the study session, the relative content knowledge and conceptual understanding expressed by the participants, as well as the cognitive level of the problems that guided group work had a strong impact on the nature of student interactions. Nevertheless, group talk in the observed study groups was mostly focused on low-level cognitive processes. The results of our work provide insights on how to better support students' productive engagement in study groups. 相似文献
608.
609.
Christian Moro Zane Štromberga Athanasios Raikos Allan Stirling 《Anatomical sciences education》2017,10(6):549-559
Although cadavers constitute the gold standard for teaching anatomy to medical and health science students, there are substantial financial, ethical, and supervisory constraints on their use. In addition, although anatomy remains one of the fundamental areas of medical education, universities have decreased the hours allocated to teaching gross anatomy in favor of applied clinical work. The release of virtual (VR) and augmented reality (AR) devices allows learning to occur through hands‐on immersive experiences. The aim of this research was to assess whether learning structural anatomy utilizing VR or AR is as effective as tablet‐based (TB) applications, and whether these modes allowed enhanced student learning, engagement and performance. Participants (n = 59) were randomly allocated to one of the three learning modes: VR, AR, or TB and completed a lesson on skull anatomy, after which they completed an anatomical knowledge assessment. Student perceptions of each learning mode and any adverse effects experienced were recorded. No significant differences were found between mean assessment scores in VR, AR, or TB. During the lessons however, VR participants were more likely to exhibit adverse effects such as headaches (25% in VR P < 0.05), dizziness (40% in VR, P < 0.001), or blurred vision (35% in VR, P < 0.01). Both VR and AR are as valuable for teaching anatomy as tablet devices, but also promote intrinsic benefits such as increased learner immersion and engagement. These outcomes show great promise for the effective use of virtual and augmented reality as means to supplement lesson content in anatomical education. Anat Sci Educ 10: 549–559. © 2017 American Association of Anatomists. 相似文献
610.
Christian Bay 《Interchange》1988,19(1):54-59
Christian Bay will respond to the interchanges by Jan Narveson and Larry Haworth (see pp. 60–75 of this issue) in a forthcoming issue ofInterchange. 相似文献