Asymmetry of red blood cell motions in a microchannel with a diverging and converging bifurcation

In microcirculation, red blood cells (RBCs) flowing through bifurcations may deform considerably due to combination of different phenomena that happen at the micro-scale level, such as: attraction effect, high shear, and extensional stress, all of which may influence the rheological properties and flow behavior of blood. Thus, it is important to investigate in detail the behavior of blood flow occurring at both bifurcations and confluences. In the present paper, by using a micro-PTV system, we investigated the variations of velocity profiles of two working fluids flowing through diverging and converging bifurcations, human red blood cells suspended in dextran 40 with about 14% of hematocrit level (14 Hct) and pure water seeded with fluorescent trace particles. All the measurements were performed in the center plane of rectangular microchannels using a constant flow rate of about 3.0 × 10⁻¹² m³/s. Moreover, the experimental data was compared with numerical results obtained for Newtonian incompressible fluid. The behavior of RBCs was asymmetric at the divergent and convergent side of the geometry, whereas the velocities of tracer particles suspended in pure water were symmetric and well described by numerical simulation. The formation of a red cell-depleted zone immediately downstream of the apex of the converging bifurcation was observed and its effect on velocity profiles of RBCs flow has been investigated. Conversely, a cell-depleted region was not formed around the apex of the diverging bifurcation and as a result the adhesion of RBCs to the wall surface was enhanced in this region.     

Mathematics learning and assessment using MathE platform: A case study

Education and Information Technologies - Universities are encouraging the implementation of innovative methodologies and teaching strategies to develop an interactive and appealing educational...     

The preparation of Fijian school leaders: a framework for principal preparation in a South Pacific context

ABSTRACT

Increased school autonomy and a greater focus on achieving school effectiveness and improvement has made it essential to reconsider the role of school leaders (OECD 2009, Creating Effective Teaching and Learning Environments: First Results from TALIS. Paris: OECD Publishing). This recommends that leadership development in this rapidly changing world deserves significant consideration compared to the past. With the increasing interest entrusted to school leadership, this article reports on how school leaders are currently prepared by the higher education programmes offered in two out of three universities in Fiji. Through an extensive literature review as well as through programme documents and policy reviews, this article focuses on current educational leadership post-graduate courses offered at these Fijian universities and highlight areas of strengths as well as suggests recommendations for improvement that are in line with identified needs for effective principal preparation in a Fijian context with key connections made to the larger South Pacific region.     

Non-anthropocentric Reasoning in Children: Its incidence when they are confronted with ecological dilemmas

This study used an individual structured interview to (1) verify the incidence of non-anthropocentric reasoning in 123 children attending the 3rd and 4th years in three primary schools in the Lisbon area (Portugal), when they are confronted with ecological dilemmas and (2) establish those places they frequented which permit animal contact. The results show a greater incidence of non-anthropocentric reasoning than that obtained in other international studies. This may be related to the focus of the questions asked, which invited children to imagine themselves as another animal or to present situations where human interaction is unfair. This incidence was found independently of gender, school origin and whether or not pets were owned, even with the more biologically complex animals. School year was the only variable proven to make a difference in conceptually more demanding questions. We also verified that the children's general past experience of nature is essentially aligned to ‘controlled environments depending on ongoing human management’, confirming a decline in direct contact with ‘natural and semi-natural environments’. However, this type of experience does not seem to exert a negative influence on their non-anthropocentric reasoning.     

Educational technology: a presupposition of equality?

The work of philosopher Jacques Rancière is used conceptually and methodologically to frame an exploration of the driving interests in educational technology policy and the sanctioning of particular discursive constructions of pedagogy that result. In line with Rancière’s thinking, the starting point for this analysis is that of equality – that people are legally, morally, intellectually, and in their everyday practices discursively equal. The use of Rancière’s concepts, demos, police, and politics, to analyse three educational technology policies internationally shows that teachers are positioned within these policies as discursively unequal, and as intellectually inferior, not only in terms of technology expertise, but crucially as pedagogues. This positioning has important implications for teachers and teacher education. Teachers are capable of recognising and critiquing inequality, and this article makes a case for an act of politics that aims to reconfigure allocated identities and power imbalances in the educational technology order.     

Self-training through the Internet

The development of five courses, aimed at advanced engineering training, using the Internet, is described in this paper. A European consortium was responsible for the development, implementation and testing of the courses through the organization of virtual classes on the Internet. An important outcome was the definition of the training service characteristics, which led to the development of a quality system based on four fundamental concepts: credit, accreditation, certification and qualification. Professionals of several age groups and industrial sectors with different expectations as well as engineering students attended pilot virtual classes. From the trainee's side, we report on how the training opportunity was received and how the training service provided was felt. The main project successes and a few weak points and a number of important recommendations are listed for future reference.     

Reading and spelling acquisition in European Portuguese: a preliminary study

We investigated the initial development of reading and spelling in European Portuguese. First-graders, tested in February and June, had to read and spell words and pseudowords. In February there were regularity and graphemic complexity effects, indicating that these children relied on grapheme–phoneme conversion. The lexicality effect found in spelling, in June, suggest that by the end of first grade these children had begun to construct an orthographic lexicon. However, lexical addressing is not inconsistent with phonological mediation as regularization errors increased between the sessions. Additionally, the previously reported similarity in global performance of Portuguese and French beginning readers may conceal processing differences that are related to specific characteristics of the corresponding orthographic codes.

Parasympathetic activity delayed after self-paced exercise

The main purpose of this study was to compare the effect of the constant load and self-paced exercise with similar total work on autonomic control after endurance exercise. Ten physically active men were submitted to (i) a maximal incremental exercise test, (ii) a 4-km cycling time trial (4-km TT), and (iii) a constant workload test with identical total external work performed at 4-km TT. Gas exchange was measured throughout the tests, while blood lactate, heart rate, and heart rate variability (HRV) were measured during the passive recovery. Power output measured at the last lap (i.e. 3600–4000?m) of 4-km TT (316?±?89?W) was statistically higher than power output measured at the end of the constant workload exercise (211?±?42?W). The 4-km TT produced higher values of blood lactate concentration (8.8?±?2.1?mmol?L^?1) than the constant workload test (7.8?±?2.1?mmol?L^?1). The heart rate recovery measured at 60?s (constant workload: 37?±?7?bpm; 4-km TT: 30?±?6) and 120?s (constant workload: 57?±?9?bpm; 4-km TT: 51?±?9?bpm) were higher in the constant workload than in the self-paced exercise. The HRV (i.e. RMSSD30s) was statistically higher in the constant load exercise measured at 120, 420, 450, 480, 540, and 570?s than the self-paced exercise. These findings suggest that the autonomic control responses were dependent of the endurance exercise modalities, with parasympathetic activity being delayed after self-paced exercise, as evidenced by post-exercise heart rate indices.     

Proximity-to-goal as a constraint on patterns of behaviour in attacker-defender dyads in team games

The aim of this study was to determine whether spatiotemporal interactions between footballers and the ball in 1 vs. 1 sub-phases are influenced by their proximity to the goal area. Twelve participants (age 15.3 ± 0.5 years) performed as attackers and defenders in 1 vs. 1 dyads across three field positions: (a) attacking the goal, (b) in midfield, and (c) advancing away from the goal area. In each position, the dribbler was required to move beyond an immediate defender with the ball towards the opposition goal. Interactions of attacker-defender dyads were filmed with player and ball displacement trajectories digitized using manual tracking software. One-way repeated measures analysis of variance was used to examine differences in mean defender-to-ball distance after this value had stabilized. Maximum attacker-to-ball distance was also compared as a function of proximity-to-goal. Significant differences were observed for defender-to-ball distance between locations (a) and (c) at the moment when the defender-to-ball distance had stabilized (a: 1.69 ± 0.64 m; c: 1.15 ± 0.59 m; P < 0.05). Findings indicate that proximity-to-goal influenced the performance of players, particularly when attacking or advancing away from goal areas, providing implications for training design in football. In this study, the task constraints of football revealed subtly different player interactions than observed in previous studies of dyadic systems in basketball and rugby union.