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The Landau theory of phase transitions occupies a centerpiece position in physics. We illustrate the theory by a pedagogical example at the pre-university level. In the example a bead of mass is threaded on a ring which is set rotating about a vertical diameter. The dynamics of the bead mimics key features of the Landau theory. 相似文献
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Prema Nedungadi Raghu Raman 《Educational technology research and development : ETR & D》2012,60(4):659-678
Most personalized learning systems are designed for either personal computers (e-learning) or mobile devices (m-learning). Our research has resulted in a cloud-based adaptive learning system that incorporates mobile devices into a classroom setting. This system is fully integrated into the formative assessment process and, most importantly, coexists with the present e-learning environment. Unlike many mobile learning systems, this system provides teachers with real-time feedback about individual and group learners. Its scalable and extendable architectural framework includes the server-side pedagogical recommendation of content adaptation based on the users?? knowledge-levels and preferences. Content is also automatically adapted to the end device that is being used. This context-aware delivery allows users to switch between e-learning and m-learning, and between devices, without any loss in personalized content. Our work builds on a web-based Adaptive Learning and Assessment System (ALAS) that is built on the Knowledge Space Theory model. At present, this system is used at school computer labs and our goal was to widen this user-base by enhancing this system to support personalized learning on mobile devices. This study describes our process of developing this technology, and contains an empirical analysis of students?? performance, perceptions, and achievements when using ALAS on both personal computers and mobile devices. 相似文献
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Vasanth Raj P Nitesh K Sagar Gang S Hitesh Jagani V Raghu Chandrashekhar H Venkata Rao J Mallikarjuna Rao C Udupa N 《Indian journal of clinical biochemistry : IJCB》2010,25(4):349-356
Objective of this study was to obtain a better understanding of the mechanism responsible for the d-galactosamine (d-GalN) induced hepatotoxicity and to study the effect of catechin against d-GalN induced hepatotoxicity. Catechin 50 and 100 mg/kg b.wt was administered for 1 week by oral route. Liver damage was induced
by intra-peritoneal administration of 400 mg/kg b.wt d-galactosamine on the last day of catechin treatment. At the end of treatment all animals were killed and liver enzyme levels
were estimated. Dissected hepatic samples were used for histopathology, RNA isolation, expression studies of Bax, Bcl-2 and
p53 mRNA levels and mitochondrial membrane potential studies. We found that increases in the liver enzyme activity and decrease
in antioxidant enzyme activity by d-GalN were significantly restricted by oral pretreatment with catechin. Disruption of mitochondrial membrane potential, up
regulation of p53, Bax and down regulation of Bcl-2 mRNA levels in the liver of d-GalN intoxicated rats were effectively prevented by pretreatment with catechin. 相似文献
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This study was undertaken to evaluate the effects of n-3 fatty acid supplementation on blood glucose, lipid profile and cytokines
in humans. Twenty adult healthy subjects were supplemented with 1g/day fish oil concentrate capsules for 2 weeks. Fasting
blood samples were taken at baseline and again after 2 week intervention. Fish oil supplementation significantly lowered fasting
serum concentrations of total cholesterol, triacylglycerol, very low density lipoprotein and low density lipoprotein (P <
0.01). Also high density lipoprotein increased significantly compared with baseline value (P < 0.01). Fish oil did not significantly
altere the fasting blood glucose concentration but significantly reduced the serum cytokines (P < 0.001). This study demonstrated
that eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) supplementation altered serum lipids, lipoprotein and cytokine
concentrations in normal human subjects even at the small dose of 660 mg of EPA plus DHA per day. It appears that EPA plus
DHA can be a safe and perhaps beneficial supplement to inflammatory diseases. 相似文献
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Bricolage versus breakthrough: distributed and embedded agency in technology entrepreneurship 总被引：2，自引：0，他引：2
We develop a perspective on technology entrepreneurship as involving agency that is distributed across different kinds of actors. Each actor becomes involved with a technology, and, in the process, generates inputs that result in the transformation of an emerging technological path. The steady accumulation of inputs to a technological path generates a momentum that enables and constrains the activities of distributed actors. In other words, agency is not only distributed, but it is embedded as well. We explicate this perspective through a comparative study of processes underlying the emergence of wind turbines in Denmark and in United States. Through our comparative study, we flesh out “bricolage” and “breakthrough” as contrasting approaches to the engagement of actors in shaping technological paths. 相似文献