A three dimensional thermoplastic microfluidic chip for robust cell capture and high resolution imaging     

Guillaume Mottet  Karla Perez-Toralla  Ezgi Tulukcuoglu  Francois-Clement Bidard  Jean-Yves Pierga  Irena Draskovic  Arturo Londono-Vallejo  Stephanie Descroix  Laurent Malaquin  Jean Louis Viovy 《Biomicrofluidics》2014,8(2)

We present a low cost microfluidic chip integrating 3D micro-chambers for the capture and the analysis of cells. This device has a simple design and a small footprint. It allows the implementation of standard biological protocols in a chip format with low volume consumption. The manufacturing process relies on hot-embossing of cyclo olefin copolymer, allowing the development of a low cost and robust device. A 3D design of microchannels was used to induce high flow velocity contrasts in the device and provide a selective immobilization. In narrow distribution channels, the liquid velocity induces a shear stress that overcomes adhesion forces and prevents cell immobilization or clogging. In large 3D chambers, the liquid velocity drops down below the threshold for cell attachment. The devices can be operated in a large range of input pressures and can even be handled manually using simple syringe or micropipette. Even at high flow injection rates, the 3D structures protect the captured cell from shear stress. To validate the performances of our device, we implemented immuno-fluorescence labeling and Fluorescence in Situ Hybridization (FISH) analysis on cancer cell lines and on a patient pleural effusion sample. FISH is a Food and Drug Administration approved cancer diagnostic technique that provides quantitative information about gene and chromosome aberration at the single cell level. It is usually considered as a long and fastidious test in medical diagnosis. This process can be easily implanted in our platform, and high resolution fluorescence imaging can be performed with reduced time and computer intensiveness. These results demonstrate the potential of this chip as a low cost, robust, and versatile tool adapted to complex and demanding protocols for medical diagnosis.  相似文献   

A perspective on optical developments in microfluidic platforms for Caenorhabditis elegans research     

Guillaume Aubry  Hang Lu 《Biomicrofluidics》2014,8(1)

Microfluidics offers unique ways of handling and manipulating microorganisms, which has particularly benefited Caenorhabditis elegans research. Optics plays a major role in these microfluidic platforms, not only as a read-out for the biological systems of interest but also as a vehicle for applying perturbations to biological systems. Here, we describe different areas of research in C. elegans developmental biology and behavior neuroscience enabled by microfluidics combined with the optical components. In particular, we highlight the diversity of optical tools and methods in use and the strategies implemented in microfluidics to make the devices compatible with optical techniques. We also offer some thoughts on future challenges in adapting advancements in optics to microfluidic platforms.  相似文献   

Groupitizing reflects conceptual developments in math cognition and inequities in math achievement from childhood through adolescence     

Mathieu Guillaume  Ethan Roy  Amandine Van Rinsveld  Gillian S. Starkey  Project iLead Consortium  Melina R. Uncapher  Bruce D. McCandliss 《Child development》2023,94(2):335-347

Understanding the cognitive processes central to mathematical development is crucial to addressing systemic inequities in math achievement. We investigate the “Groupitizing” ability in 1209 third to eighth graders (mean age at first timepoint = 10.48, 586 girls, 39.16% Asian, 28.88% Hispanic/Latino, 18.51% White), a process that captures the ability to use grouping cues to access the exact value of a set. Groupitizing improves each year from late childhood to early adolescence (d = 3.29), is a central predictor of math achievement (beta weight = .30), is linked to conceptual processes in mathematics (minimum d = 0.69), and helps explain the dynamic between the ongoing development of non-symbolic number concepts, systemic educational inequities in school associated with SES, and mathematics achievement (minimum beta weight = .11) in ways that explicit symbolic measures may miss.  相似文献   

Relationship between split-step timing and leg stiffness in world-class tennis players when returning fast serves     

Sami Mecheri  Guillaume Laffaye  Céline Triolet  David Leroy  Matt Dicks  Mohamed A. Choukou 《Journal of sports sciences》2013,31(17):1962-1971

ABSTRACT

This study investigated split-step timing when returning serves and whether this timing is related to neuromechanical capabilities in world-class tennis players. In Experiment 1, the split-step timing of four groups of world-class players (male and female ATP/WTA seniors, and ITF juniors) was measured on court when returning serves of the same level players. The four groups initiated the split-step at a similar time, starting around the time ball-racket contact in the serve stroke and landed when early ball-flight information was available. In Experiment 2, the neuromechanical capabilities (leg stiffness and vertical jump performance) of a group of world-class players and three groups of less-skilled tennis players were examined. The results showed an increase in leg stiffness with an increase in the level of expertise. A cross-experiment analysis in world-class male players (ATP/ITF, n = 10) revealed that the timing of initial foot movement was significantly correlated with the leg stiffness (r² = 0.54), with later lateral step after the serve in the players who had higher stiffness. The findings support the hypothesis that world-class tennis players adapt perceptual-motor control on the basis of their neuromechanical capabilities and maximise the time before initiating their interceptive action to rely on more reliable information.  相似文献   

The role of location and social strength for friendship prediction in location-based social networks     

Jorge C. Valverde-Rebaza  Mathieu Roche  Pascal Poncelet  Alneu de Andrade Lopes 《Information processing & management》2018,54(4):475-489

Recent advances in data mining and machine learning techniques are focused on exploiting location data. These advances, combined with the increased availability of location-acquisition technology, have encouraged social networking services to offer to their users different ways to share their location information. These social networks, called location-based social networks (LBSNs), have attracted millions of users and the attention of the research community. One fundamental task in the LBSN context is the friendship prediction due to its role in different applications such as recommendation systems. In the literature exists a variety of friendship prediction methods for LBSNs, but most of them give more importance to the location information of users and disregard the strength of relationships existing between these users. The contributions of this article are threefold, we: 1) carried out a comprehensive survey of methods for friendship prediction in LBSNs and proposed a taxonomy to organize the existing methods; 2) put forward a proposal of five new methods addressing gaps identified in our survey while striving to find a balance between optimizing computational resources and improving the predictive power; and 3) used a comprehensive evaluation to quantify the prediction abilities of ten current methods and our five proposals and selected the top-5 friendship prediction methods for LBSNs. We thus present a general panorama of friendship prediction task in the LBSN domain with balanced depth so as to facilitate research and real-world application design regarding this important issue.  相似文献   

How does the tennis serve technique influence the serve-and-volley?     

Martin C  Bideau B  Nicolas G  Delamarche P  Kulpa R 《Journal of sports sciences》2012,30(11):1149-1156

In tennis, a high ball velocity and a fast run toward the net are key features to successful performance of "serve-and-volley" players. For the serve, tennis players can use two techniques: the foot-up (FU) or foot-back (FB) technique. The aim of this study was to determine if the running time toward the net after the serve and the ball velocity (V(ball)) vary between these two techniques. Moreover we analysed the angular momentum values of the trunk and of the arm holding the racquet. Fifteen expert tennis players performed six successful serve-and-volleys with both techniques. Running time to the net is significantly lower for FB, whereas V(ball) is significantly higher for FU. Trunk and arm angular momentums about the transverse axis are significantly higher with FU before ball impact. A significant correlation (r = 0.81, P < 0.001) exists between changes in the maximal trunk angular momentum and in running time to the net between the two serve techniques. A significant correlation (r = 0.84, P < 0.001) also exists between changes in the maximal trunk angular momentum and in V(ball) between the two serve techniques. According to these results, FB is the best technique for moving as quickly as possible to the net because of a lower trunk angular momentum.  相似文献   

Spatiotemporal analysis of 3D kinematic asymmetry in professional cycling during an incremental test to exhaustion     

Camille Pouliquen  Guillaume Nicolas  Benoit Bideau  Gérard Garo  Armand Megret  Paul Delamarche 《Journal of sports sciences》2018,36(19):2155-2163

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The prognostic relevance of psychological factors with regard to participation and success in table-tennis     

Guillaume Martinent  Valérian Cece  Marije Titia Elferink-Gemser  Irene Renate Faber  Jean-Claude Decret 《Journal of sports sciences》2018,36(23):2724-2731

ABSTRACT

This study examined the prognostic relevance of self-determined motivation, coping, burnout, perceived stress and recovery experienced by 159 youth table-tennis players involved in intensive training centers with regard to their participation and success six years later. Results of ANCOVAs showed that players who still practiced at time 2 (T2; six years later; n = 130) reported lower time 1 (T1; while they were involved in intensive training centers) amotivation (large effect), disengagement-oriented coping, sport devaluation and reduced accomplishment (moderate effects) than their counterparts who dropped out at T2 (n = 29). Results of ANCOVAs also showed that international (n = 18) and/or national players (n = 86) at T2 reported significantly lower T1 amotivation (large effect), disengagement-oriented coping and sport devaluation (moderate effects) in comparison to regional (n = 26) players at T2. Finally results of correlational analyses showed that T2 performance and/or six-year performance progress were significantly and weakly correlated with introjected and external regulations, perceived stress and perceived recovery, and significantly and moderately correlated with amotivation, disengagement-oriented coping, sport devaluation, and reduced accomplishment. Overall, this study provided insights into the role played by self-determined motivation, coping, burnout, perceived stress and recovery in the table-tennis players’ dropout and performance level six years later.  相似文献   

Changes in student effort and grade expectation in the course of a term     

C. S. Khachikian  D. W. Guillaume  T. K. Pham 《European Journal of Engineering Education》2011,36(6):595-605

Students were surveyed and asked to self-evaluate their performance and time-on-task in six engineering courses (eight sections). Surveys were conducted four times over the course of a 10-week quarter. Students with the highest grade point averages (GPAs) (2.88 mean; 4.00 mode) indicated ‘no change’ while students with lower GPAs (2.67 mean; 1.83 mode) indicated a ‘negative change’ in grade expectations by the end of the quarter, indicating that better performing students are better self-evaluators. Students reduced time-on-task 2–4 hours/week, especially early in the quarter. Students who changed their time-on-task during each survey had a GPA mode of 4.00, indicating that ‘master’ students readily adapt to course demands. This study shows that most students over-predict their grades and their level of commitment to a course and lose confidence in their abilities as the term progresses. It is suggested that instructors obtain student grade predictions and use them to provide timely and appropriate feedback.  相似文献   

Differences in career self-efficacy among women     

Peggy Smith Mathieu M.Ed.  Claudia J. Sowa Ph.D.  Spencer G. Niles D.Ed. 《Journal of Career Development》1993,19(3):187-196

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