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41.
Alan Chalmers Lloyd Ackert Pnina Abir-Am Maria Trochatos Carolyn R. Miller Nicolas Rasmussen Roy Macleod Ingo Brigandt Lorna Barrow Ian Maclean Elof Axel Carlson Susan E. Cozzens Cindy Klestinec Patricia O'Grady Alison Bashford Jim Endersby Jonathan Simon David Mercer David Oldroyd Suzanne Verderber Peter Slezak Rachel Cooper Patricia Fara Ravi Arvind Palat Peder Anker Bernhard Fritscher David Branagan 《Metascience》2002,11(3):329-429
42.
In this paper, within the framework of ordinary differential equation and eutrophication ecological theory, long-run sustainability of an impulsive switched eutrophication controlling system based upon the Zeya reservoir is studied analytically and numerically. A key advantage of the impulsive switched eutrophication controlling system is that it can be quite accurate to better describe the influence mechanism of some key factors during eutrophication controlling process, which enables a systematic and logical procedure for fitting eutrophication system to real monitoring data. Mathematical theoretical works have been pursuing the investigation of some conditions for all species persistence, which can deduce a standard parameter control relationship and in turn can provide a theoretical basis for the numerical simulation. Numerical analysis indicates that the theoretical results are correct and the long-run substainability of the impulsive switched eutrophication controlling system mainly depends on some critical parameters. It should also be stressed that the values of some critical parameter can be determined by a standard parameter control relationship. In addition, it is successful to show that the standard parameter control relationship maybe be used as an explicit threshold function to judge the long-run sustainability of eutrophication controlling process for the Zeya reservoir. Finally, all these results are expected to be of use in the study of the dynamic complexity of eutrophication ecosystems. 相似文献
43.
This research endeavors to understand whether certain professors have customer-based brand equity (CBBE) in the minds of students. Consequently, the purpose of this study is to conceptualize, develop, and empirically test a model of customer-based professor brand equity. Survey data gathered from 465 undergraduate business students were used to test the model. Structural equation modeling (SEM) analysis findings indicate that certain professors do indeed have CBBE and the transference of the brand-building effort can be successfully applied to professors who are willing to be strong brands. The results show that professor brand characteristics – quality of instruction, competence, and reputation – have an influence on students' feelings of attachment to the professor and to the quality of relationships with the professor brand and therefore, professor brand equity. The ultimate goal of most professors is to inculcate lifelong student learning, but this worthy pursuit gains wings through the professor brand-building effort. 相似文献
44.
The nematodes (worms) Caenorhabditiselegans and Caenorhabditisbriggsae are well-known model organisms to study the basis of animal development and behaviour. Their sinusoidal pattern of movement is highly stereotypic and serves as a tool to monitor defects in neurons and muscles that control movement. Until recently, a simple yet robust method to initiate movement response on-demand did not exist. We have found that the electrical stimulation in a microfluidic channel, using constant DC electric field, induces movement (termed electrotaxis) that is instantaneous, precise, sensitive, and fully penetrant. We have further characterized this behaviour and, in this paper, demonstrate that electrotaxis can also be induced using a pulse DC electric signal. Worms responded to pulse DC signals with as low as 30% duty cycle by moving towards the negative electrode at the same speed as constant DC fields (average speed of C. elegans?=?296?±?43?μm/s and C. briggsae?=?356?±?20?μm/s, for both constant and pulse DC electric fields with various frequencies). C. briggsae was found to be more sensitive to electric signals compared to C. elegans. We also investigated the turning response of worms to a change in the direction of constant and pulse DC signals. The response for constant DC signal was found to be instantaneous and similar for most worms. However, in the case of pulse DC signal, alterations in duty cycle affected the turning response time as well as the number of responding worms. Our findings show that pulse DC method allows quantitative measurement of response behaviour of worms and suggest that it could be used as a tool to study the neuronal basis of such a behaviour that is not observed under constant DC conditions. 相似文献