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11.
Selection medium is important in sperm isolation for assisted reproductive technologies. Contrary to the naturally occurring human cervical mucus which has a high viscosity, most current practices for motility based sperm selection use a low viscosity medium. In this study, we used a microfluidic device to assess the effects of high viscosity media made with hyaluronic acid (HA) and methyl cellulose (MC) on bovine and human sperm motility and viability (sperm transferred directly from cryoprotectant). The microfluidic penetration test, viability, and motility were compared for sperm swimming in both HA and MC media with about 20cp viscosity (measured at 20 °C). Our resulted indicate that MC medium resulted in a significantly higher number of viable bovine sperm penetrating the medium as compared to HA. Furthermore, MC resulted in the selection of a sperm subpopulation with a 274% increase in sperm viability in comparison to the raw semen, while HA increased viability by only 133%. In addition to viability, bovine sperm motility parameters were significantly higher in the MC medium as compared with HA. Experiments with human sperm swimming in MC indicate that sperm swim slower and straighter at higher viscosities. In conclusion, the results indicate that in a micro-confined environment representative of the in vivo environment, MC is a preferred high viscosity medium to ensure the highest concentration of motile and viable sperm. 相似文献
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Hasse,Cathrine (2015) An anthropology of learning. Springer (Berlin) isbn 978‐94‐017‐9605‐7 320 pp £90 (ebook £72) http://www.springer.com/us/book/9789401796057# 下载免费PDF全文
Mohammad Ali Salmani Nodoushan 《British journal of educational technology : journal of the Council for Educational Technology》2015,46(6):E30-E31
This book combines cultural models with practice‐based learning to develop a new theory of cultural learning. Drawing on insights from anthropology, it argues how collective and social cultures can emerge from an “engaged” learning process. The book opens a new window on human learning; however, you will probably find only parts of it of some interest or use. Mohammad Ali Salmani Nodoushan 相似文献
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This paper discusses the problem of the fuzzy sliding mode control for a class of disturbed systems. First, a fuzzy auxiliary controller is constructed based on a feedback signal not only to estimate the unknown control term, but also participates in the sliding mode control due to the fuzzy rule employed. Then, we extend our theory into the cases, where some kind of system information can not be obtained, for better use of our theoretical results in real engineering. Finally, some typical numerical examples are included to demonstrate the effectiveness and advantage of the designed sliding mode controller. 相似文献
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In this paper a new integrated observer-based fault estimation and accommodation strategy for discrete-time piecewise linear (PWL) systems subject to actuator faults is proposed. A robust estimator is designed to simultaneously estimate the state of the system and the actuator fault. Then, the estimate of fault is used to compensate for the effect of the fault. By using the estimate of fault and the states, a fault tolerant controller using a PWL state feedback is designed. The observer-based fault-tolerant controller is obtained by the interconnection of the estimator and the state feedback controller. We show that separate design of the state feedback and the estimator results in the stability of the overall closed-loop system. In addition, the input-to-state stability (ISS) gain for the closed-loop system is obtained and a procedure for minimizing it is given. All of the design conditions are formulated in terms of linear matrix inequalities (LMI) which can be solved efficiently. Also, performance of the estimator and the state feedback controller are minimized by solving convex optimization problems. The efficiency of the method is demonstrated by means of a numerical example. 相似文献
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This paper deals with the problem of adaptive output feedback neural network controller design for a SISO non-affine nonlinear system. Since in practice all system states are not available in output measurement, an observer is designed to estimate these states. In comparison with the existing approaches, the current method does not require any information about the sign of control gain. In order to handle the unknown sign of the control direction, the Nussbaum-type function is utilized. In order to approximate the unknown nonlinear function, neural network is firstly exploited, and then to compensate the approximation error and external disturbance a robustifying term is employed. The proposed controller is designed based on strict-positive-real (SPR) Lyapunov stability theory to ensure the asymptotic stability of the closed-loop system. Finally, two simulation studies are presented to demonstrate the effectiveness of the developed scheme. 相似文献
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Mohammad Akshir Ab Kadir 《Cambridge Journal of Education》2017,47(2):227-246
Among the major policies that have been implemented to ensure its continued success, Thinking Schools, Learning Nation (TSLN) has been described as the ‘big bang of educational reforms’ in Singapore. However, while the policy aims to develop critical thinkers in school leavers, the corporatisation of education in the shape of structures such as the school excellence model seems to be at odds with TSLN. This paper argues that these structures unwittingly engender a culture of performativity among schools, marginalising the central outcome of its initiative that entails developing a culture of thinking and thinkers. The tension is further exacerbated by the larger rationalities that have shaped Singapore and the pragmatic and instrumental philosophy which underpins its educational system. The tensions generated by the clash between intended (culture of thinking) and engendered culture (culture of performativity) present the challenge of mediation for the system on its path to realising TSLN. 相似文献
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Zeinab Echreshavi Mokhtar Shasadeghi Mohammad Hassan Asemani 《Journal of The Franklin Institute》2021,358(1):575-605
This paper focuses on a systematic constrained fuzzy integral sliding mode controller design for a class of uncertain discrete-time nonlinear systems which can be represented as Takagi-Sugeno (T-S) fuzzy models. The contributions are to consider constraints on the control input amplitude and control input amplitude rate and to extend the existing pole-placement design technique for designing gain matrices of the fuzzy sliding surface. Moreover, a dynamic-gain observer along with performance is proposed for attenuating disturbance, which generalizes the existing results on the Proportional Observer (PO), the Proportional Integral Observer (PIO) and the dynamic observer (DO). Finally, the dynamic-observer-based constrained fuzzy integral sliding mode controller is designed. All the proposed design conditions are represented in terms of LMIs-based ones. The methods are studied for not only single-input single-output (SISO) but also multi-input multi-output (MIMO) systems. In the end, the proposed approaches are evaluated on practical and numerical systems to illustrate the superiority of the proposed control scheme. 相似文献
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