Reduction of water evaporation in polymerase chain reaction microfluidic devices based on oscillating-flow

Producing polymeric or hybrid microfluidic devices operating at high temperatures with reduced or no water evaporation is a challenge for many on-chip applications including polymerase chain reaction (PCR). We study sample evaporation in polymeric and hybrid devices, realized by glass microchannels for avoiding water diffusion toward the elastomer used for chip fabrication. The method dramatically reduces water evaporation in PCR devices that are found to exhibit optimal stability and effective operation under oscillating-flow. This approach maintains the flexibility, ease of fabrication, and low cost of disposable chips, and can be extended to other high-temperature microfluidic biochemical reactors.     

Phonological working memory, phonological awareness and language in literacy difficulties in Brazilian children

One of the most usual flaws that lead to literacy disability regards cognitive difficulties and alterations some children present in the literacy process. Many studies have found alterations in phonological processing, more specifically in phonological working memory (PWM) and phonological awareness (PA). Therefore, our aim was to identify alterations in skills of phonological working memory, phonological awareness and language (semantic, syntactic and phonological aspects) of Brazilian children with literacy disabilities (age 7–8). They were divided into two groups: (1) Group of Normal Literacy (NL); and (2) Group With Literacy Disabilities (LD). The evaluation comprised tests that assessed general cognitive functions and the skills at stake. The LD presented a poorer performance than the NL in the skills of PWM, PA and language aspects. The factor analysis showed that these skills prevailed in differentiating the groups. Thus, children with literacy disabilities presented deficits in phonological processing and language. These deficits seem to be a result of alterations of the phonological representations and poor language skills that are prior to the literacy period. Consequently, we believe that the early identification of these alterations can be very useful for the prevention of future literacy problems.     

Teaching About Energy

Science & Education - In this article, we draw upon the Conceptual Profile Theory to discuss the negotiation of meanings related to the energy concept in an 11th grade physics classroom. This...     

Fault-tolerant sensorless control of wind turbines achieving efficiency maximization in the presence of electrical faults

This paper proposes a sensorless fault-tolerant control strategy solving the tracking problem of the maximum delivered power characteristic for a wind energy conversion system equipped with a permanent magnet synchronous generator. A previously published control scheme ensuring the maximum power efficiency of the wind turbine, not requiring feedback information about rotor speed and position, and about wind velocity, is here extended to make the control scheme fault-tolerant with respect to possible electrical faults affecting the equations of the permanent magnet synchronous generator (PMSG) in the original (α, β) frame. The control law is based on a number of interconnected nonlinear observers. Closed loop asymptotic vanishing of the observation errors is proved. The proposed control solution has been validated on the National Renewable Energy Laboratory (NREL) 5-MW three-blade wind turbine model.     

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.     

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.