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Rupprecht P Golé L Rieu JP Vézy C Ferrigno R Mertani HC Rivière C 《Biomicrofluidics》2012,6(1):14107-1410712
We have developed a method for studying cellular adhesion by using a custom-designed microfluidic device with parallel non-connected tapered channels. The design enables investigation of cellular responses to a large range of shear stress (ratio of 25) with a single input flow-rate. For each shear stress, a large number of cells are analyzed (500–1500 cells), providing statistically relevant data within a single experiment. Besides adhesion strength measurements, the microsystem presented in this paper enables in-depth analysis of cell detachment kinetics by real-time videomicroscopy. It offers the possibility to analyze adhesion-associated processes, such as migration or cell shape change, within the same experiment. To show the versatility of our device, we examined quantitatively cell adhesion by analyzing kinetics, adhesive strength and migration behaviour or cell shape modifications of the unicellular model cell organism Dictyostelium discoideum at 21 °C and of the human breast cancer cell line MDA-MB-231 at 37 °C. For both cell types, we found that the threshold stresses, which are necessary to detach the cells, follow lognormal distributions, and that the detachment process follows first order kinetics. In addition, for particular conditions’ cells are found to exhibit similar adhesion threshold stresses, but very different detachment kinetics, revealing the importance of dynamics analysis to fully describe cell adhesion. With its rapid implementation and potential for parallel sample processing, such microsystem offers a highly controllable platform for exploring cell adhesion characteristics in a large set of environmental conditions and cell types, and could have wide applications across cell biology, tissue engineering, and cell screening. 相似文献
85.
Miarka B Panissa VL Julio UF Del Vecchio FB Calmet M Franchini E 《Journal of sports sciences》2012,30(9):899-905
The aim of this study was to compare time-motion indicators during judo matches performed by athletes from different age groups. The following age groups were analysed: Pre-Juvenile (13-14 years, n = 522), Juvenile (15-16 years, n = 353); Junior (19 years, n = 349) and Senior (>20 years, n = 587). The time-motion indicators included: Total Combat Time, Standing Combat Time, Displacement Without Contact, Gripping Time, Groundwork Combat Time and Pause Time. Analysis of variance (ANOVA) one-way and the Tukey test, as well as the Kruskal-Wallis test and Mann-Whitney (for non-parametric data), were conducted, using P < 0.05 as significance level. The results showed that all analysed groups obtained a median of 7 (first quantile - 3, third quantile - 12) sequences of combat/pause cycles. In total time of combat, the result was: for Total Combat Time, Standing Combat Time and Gripping Time: Pre-Juvenile and Senior were significantly longer than Juvenile and Junior. Considering Displacement Without Contact, Junior was significantly longer than all other age groups. For Groundwork Combat Time, Senior was significantly longer than all other age groups and Pre-Juvenile was longer than Junior. These results can be used to improve the physiological performance in intermittent practices, as well as technical-tactical training during judo sessions. 相似文献
86.
Both China and India have been experiencing a historical take-off in the use of intellectual property rights (IPR). In terms of trademark applications filed with domestic IP offices in 2009, the evidence demonstrates that China now ranks 1st worldwide and India 5th, while for patent filings China ranks 3rd worldwide and India ranks 9th. This performance is remarkable as both China and India experienced negligible demand for IPR protection as recently as two decades ago. The IPR take up trends in these two countries are analyzed in detail, highlighting the structure of patent and trademark demand since 1990. Specifically, the available series are broken down and analyzed according to: (i) national versus foreign origin of patents and trademarks; (ii) technological (IPC) and trademark (NICE) classes; and (iii) the major individual patent users in each country. The data used refers to applications in the Chinese and Indian IP offices although the demand from residents of these two countries in both the international and other national systems is also assessed. Beyond the existing momentum in IPR registrations by China and India and their capacity to maintain it into the near future, the paper addresses practical questions about the strategies, motives and benefits behind the current trends. In particular, we seek to evaluate the capacity of both China's and India's National Innovation Systems to internalize the potential returns of this increasing demand for IPR. The insight reached finds that should both China and India sustain their current IPR growth rates, they will be able to catch up with the most advanced economies within the time span of a few decades. 相似文献
87.
The aim of this paper is to characterize the distribution of number of hits and spent time by web session. It also expects to find if there are significant differences between the length and the duration of a session with regard to the point of access–search engine, link or root. Web usage mining was used to analyse 17,174 web sessions that were identified from the webometrics.info web site. Results show that both distribution of length and duration follow an exponential decay. Significant differences between the different origins of the visits were also found, being the search engines’ users those who spent most time and did more clicks in their sessions. We conclude that a good SEO policy would be justified, because search engines are the principal intermediaries to this web site. 相似文献
88.
Training and psychosocial patterns during the early development of Portuguese national team athletes
This study explored the early development of expert athletes compared to a group of athletes that did not achieve an expert level of performance despite being involved in youth events with their national squads. In particular, the activities, training patterns, and psychosocial influences that characterized their paths in competitive sports were examined. Male and female participants (N?=?42) from different sports were interviewed. Overall, athletes showed several commonalities. However, experts were selected to national squads later and also started thinking about investing in becoming elite athletes later. Non-experts revealed more parental pressure and less individual training with coaches. 相似文献
89.
Anjalé D. Welton Katherine Cumings Mansfield Pei-Ling Lee 《Mentoring & Tutoring: Partnership in Learning》2013,21(5):481-509
There is limited research on quantitative differences between men and women’s experiences in doctoral programs. We aim to fill that gap by sharing findings from a web-based exploratory survey of perceived gender differences on quality mentoring in educational leadership doctoral programs. According to survey results, there is limited statistical significance in terms of gender differences in programmatic supports and scholarly progress. However, women experience feelings of self-doubt due to negative experiences with advising and mentoring, including difficulties making connections to a quality mentor. Furthermore, both female and male participants shared common definitions of what constitutes quality mentorship and believed mentorship was important, but lacking in varying degrees. Finally, all participants agreed that their educational leadership preparation programs should provide additional support in terms of writing and research development. Participants also shared important recommendations for strengthening mentoring experiences as well as future research methods and foci. 相似文献
90.
Karen Krol Jeroen Janssen Simon Veenman Jos van der Linden 《Educational Research and Evaluation》2013,19(3):205-237
In this study, the effects of a school improvement program on cooperative learning (CL) with respect to the elaborations of 6th-grade students working in mixed-ability and mixed-sex dyads on 2 cooperative tasks were examined. A posttest-only design with a control group was used to investigate the provision and receipt of elaborations within the dyads and the performance of the dyads working on cooperative mathematics and language tasks. Treatment dyads were found to exchange significantly more high-level elaborations during the language task than the control dyads. The treatment dyads also tended to produce higher performance scores on the 2 tasks. 相似文献