Life under flow: A novel microfluidic device for the assessment of anti-biofilm technologies

In the current study, we have developed and fabricated a novel lab-on-a-chip device for the investigation of biofilm responses, such as attachment kinetics and initial biofilm formation, to different hydrodynamic conditions. The microfluidic flow channels are designed using computational fluid dynamic simulations so as to have a pre-defined, homogeneous wall shear stress in the channels, ranging from 0.03 to 4.30 Pa, which are relevant to in-service conditions on a ship hull, as well as other man-made marine platforms. Temporal variations of biofilm formation in the microfluidic device were assessed using time-lapse microscopy, nucleic acid staining, and confocal laser scanning microscopy (CLSM). Differences in attachment kinetics were observed with increasing shear stress, i.e., with increasing shear stress there appeared to be a delay in bacterial attachment, i.e., at 55, 120, 150, and 155 min for 0.03, 0.60, 2.15, and 4.30 Pa, respectively. CLSM confirmed marked variations in colony architecture, i.e.,: (i) lower shear stresses resulted in biofilms with distinctive morphologies mainly characterised by mushroom-like structures, interstitial channels, and internal voids, and (ii) for the higher shear stresses compact clusters with large interspaces between them were formed. The key advantage of the developed microfluidic device is the combination of three architectural features in one device, i.e., an open-system design, channel replication, and multiple fully developed shear stresses.     

Intensity of exercise recovery,blood lactate disappearance,and subsequent swimming performance

Abstract

The aim of this study was to examine the effects of active versus passive recovery on blood lactate disappearance and subsequent maximal performance in competitive swimmers. Fourteen male swimmers from the University of Virginia swim team (mean age 20.3 years, s = 4.1; stature 1.85 m, s = 2.2; body mass 81.1 kg, s = 5.6) completed a lactate profiling session during which the speed at the lactate threshold (V_LT), the speed at 50% of the lactate threshold (V_LT.5), and the speed at 150% of the lactate threshold (V_LT1.5) were determined. Participants also completed four randomly assigned experimental sessions that consisted of a 200-yard maximal-effort swim followed by 10 min of recovery (passive, V_LT.5, V_LT, V_LT1.5) and a subsequent 200-yard maximal effort swim. All active recovery sessions resulted in greater lactate disappearance than passive recovery (P < 0.0001 for all comparisons), with the greatest lactate disappearance associated with recovery at V_LT (P = 0.006 and 0.007 vs. V_LT.5 and V_LT1.5 respectively) [blood lactate disappearance was 2.1 mmol · l^?1 (s = 2.0), 6.0 mmol · l^?1 (s = 2.6), 8.5 mmol · l^?1 (s = 1.8), and 6.1 mmol · l^?1 (s = 2.5) for passive, V_LT.5, V_LT, and V_LT1.5 respectively]. Active recovery at V_LT and V_LT1.5 resulted in faster performance on time trial 2 than passive recovery (P = 0.005 and 0.03 respectively); however, only active recovery at V_LT resulted in improved performance on time trial 2 (TT₂) relative to time trial 1 (TT₁) [TT₂?TT₁: passive +1.32 s (s = 0.64), V_LT.5+1.01 s (s = 0.53), V_LT?1.67 s (s = 0.26), V_LT1.5?0.07 s (s = 0.51); P < 0.0001 for V_LT). In conclusion, active recovery at the speed associated with the lactate threshold resulted in the greatest lactate disappearance and in improved subsequent performance in all 14 swimmers. Our results suggest that coaches should consider incorporating recovery at the speed at the lactate threshold during competition and perhaps during hard training sessions.     

The association between mathematics pedagogy and learners’ dispositions for university study

We address the current concerns about teaching‐to‐the‐test and its association with declining dispositions towards further study of mathematics and the consequences for choice of STEM subjects at university. In particular, through a mixed study including a large survey sample of over 1000 students and their teachers, and focussed qualitative case studies, we explored the impact of ‘transmissionist’ pedagogic practices on learning outcomes. We report on the construction and validation of a scale to measure teachers’ self‐reported pedagogy. We then use this measure in combination with the students’ survey data and through regression modelling we illustrate significant associations between the pedagogic measure and students’ mathematics dispositions. Finally, we discuss the potential implications of these results for mathematics education and the STEM agenda.     

Using the Quality of Literacy Implementation Checklist to Improve Preschool Literacy Instruction

Despite much progress in improving the quality of preschool programs, there is still an uneven quality of instruction in early childhood settings. Providing support and professional development (PD) for teachers that is practical, systematic and sustainable is one potential avenue to increase classroom quality in preschool, including quality of literacy instruction. Preschool educators who want to focus on increasing the quality of literacy instruction need simple-to-use tools that can be implemented quickly and provide a means to assess progress towards the goal of improving literacy instruction. The Quality of Literacy Implementation checklist measures how well the teaching staff include intentional, instruction in literacy/oral language. Rather than focusing on a specific curriculum or intervention, quality of implementation focuses on the teacher’s delivery of key procedural features of evidence-based instruction. As is the case with fidelity of implementation, a quality of implementation checklist not only measures implementation but also provides a roadmap about how instruction might be modified to ensure that critical and essential skills are emphasized across the preschool day.     

Conditioned suppression of a positively reinforced shuttle response

Rats were trained to run up and down an alleyway for sucrose reinforcement on a variable interval schedule. Differential aversive classical conditioning with auditory CSs was then conducted in a separate apparatus (“off the baseline”) prior to those CSs being presented while the subjects were responding for sucrose in the alleyway. Once the effects of the CSs had extinguished, shock was reintroduced following one CS but not the other (“on the baseline” differential aversive classical conditioning). Both “off the baseline” and “on the baseline” conditioning resulted in conditioned suppression to the CS followed by shock, but little effect of the CS followed by no shock was found. In the “on the baseline” phase, total suppression of baseline responding occurred at moderate US intensities, and this appeared to result from the subject avoiding the location at which he was last shocked. At lower values, both baseline response rate and relative suppression ratio were functions of US intensity. The results are discussed in relation to the effects found in similar experiments using avoidance baselines.     

Conceptions of the Curriculum: teachers and ‘truth‘

This article draws its inspiration from the three socio‐epistemological theories of phenomenology, contextualism and traditional epistemology and their abrasive interrelation. From these foundations, a theoretical framework is devised as a basis for an exposition and interpretation of empirical work undertaken in four contrasting school contexts. The aim of the research was firstly to look for similarities between teachers’ conceptions of the curriculum and secondly to provide evidence which could be used as a basis for judging to what extent these similarities were constrained by teachers’ conceptions of ‘truth’.

The paper discusses teachers’ responses to three questions from an open‐ended questionnaire; these requested views on how far curriculum content was considered to be related: (a) to individual pupils, (b) to social requirements and (c) to ‘truth’. The discussion of each question resolves itself into a number of issues connected with these three themes.

The article is predominantly interpretative but a short appendix displays a more rigorous analysis of the distribution of the responses across the four schools. Finally, although the paper is concerned with opinions about curricula rather than with actual curricula transactions, my hope is that awareness of teachers’ ideas may provide indicators for curricular realities.     

Pupil involvement in planning topics using KWL grids: opinions of teachers,student teachers and pupils

Pupil involvement in planning is one way in which teachers listen to the “pupil voice”. This paper focuses on pupil involvement in planning class topics using KWL grids. The opinions of teachers, teacher education students and primary school pupils in Northern Ireland were sought on this using questionnaires and interviews. The vast majority of teachers and student teachers responded positively, many commenting that the pupils had reacted favourably, enthusiastically or with enjoyment, and that they seemed to be more motivated, responsive and interested in topics in which they had some “ownership”. Negative opinions expressed by teachers included arguments about difficulties in incorporating pupil ideas into their planning as well as practical concerns about using a KWL grid with younger or less able pupils. More fundamental were fears about loss of teacher control, teacher authority being undermined, and “interference” in teacher planning. One of the outcomes of the study is a list of recommendations for good practice when using KWL grids.     

Evaluating the validity of the Automated Working Memory Assessment

The aim of the present study was to investigate the construct stability and diagnostic validity of a standardised computerised tool for assessing working memory: the Automated Working Memory Assessment (AWMA). The purpose of the AWMA is to provide educators with a quick and effective tool to screen for and support those with memory impairments. Findings indicate that working memory skills in children with memory impairments are relatively stable over the course of the school year. There was also a high degree of convergence in performance between the AWMA and the WISC‐IV Working Memory Index. The educational implications are discussed.