A tapered channel microfluidic device for comprehensive cell adhesion analysis, using measurements of detachment kinetics and shear stress-dependent motion

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.     

Anthropometric profiles of elite older triathletes in the Ironman Brazil compared with those of young Portuguese triathletes and older Brazilians

The objective of this study was to describe the anthropometric profiles of elite older triathletes participating in the 2009 Ironman Brazil and to compare their somatotype, anthropometric and body composition characteristics with those of elite young triathletes and older non-athletes. The sample consisted of 64 males, divided into three groups: (1) older triathletes (n = 17), (2) young triathletes (n = 24), and (3) older non-athletes (n = 23). Somatotype was analysed according to the Carter and Heath ( 1990 ) method. Body mass index, sum of four skinfolds, percentage body fat, body fat mass, and fat-free mass were also estimated. Older non-athletes had higher endomorphy, sum of four skinfolds, fat percentage, and body fat mass than the athletes. Older athletes who participated in the Ironman and elite young triathletes had higher fat-free mass than older non-athletes. Older triathletes and older non-athletes were considered mainly endomorphic mesomorphs and young triathletes mainly ectomorphic mesomorphs. The findings that characterize the anthropometric profile of athletes in this sports modality could be used as a reference.     

Differences between web sessions according to the origin of their visits

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.     

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.     

Mentoring Matters: An Exploratory Survey of Educational Leadership Doctoral Students’ Perspectives

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.     

Effects of a Cooperative Learning Program on the Elaborations of Students Working in Dyads

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.     

Responsive Instruction for Young Children: A Study of how teachers can help easily distracted children become more attentive

In a research and development project called ‘orthopedagogisch project Afstemming’, conducted at the Utrecht University, a programme for teachers in kindergarten is designed and evaluated. It's goal is enhancing children's motivation and attention for work and play by means of responsive Instruction.     

Learning by starch potato growers: learning in small businesses with no employees

In small businesses with no employees, learning environments have a low learning readiness. Consequently, learners need to rely on their own agency to shape their learning experiences. Results from a study of agricultural entrepreneurs indicated that the components of motivation and self-regulated learning strategies shape learner's agency and explain learning environment configuration in small businesses with no employees. Configuration of the learning environment was found to be a weak determinant of the learning performance of these learners. However, results showed that prior performance of learners in small businesses with no employees dictates how their agency operates and what learning effect is achieved; higher prior performance results in higher learning effects. We conclude that mechanisms that underlie learning in traditional learning environments work similarly in learning environments in small businesses with no employees.     

Orthography and the development of metalinguistic reflection in Portuguese primary school pupils / Ortografía y desarrollo de la reflexión metalingüística en alumnos portugueses en primaria

Abstract

Linguistic awareness is crucial in learning literacy. This project has a two-fold aim: to develop the students’ ability to think about language in order to write with accuracy and to lead teachers to promote students’ discussions about their writing difficulties. The study is part of a two-year action-research project developed in primary schools from the Lisbon area, with experimental and control groups. The starting point of the project was the analysis of the problems students of third and fourth grades showed in their writing. The scope of the project includes dictation tasks within an interactionist approach, favouring grammatical discussions leading to the observation and manipulation of linguistic data.