DNA translocation through short nanofluidic channels under asymmetric pulsed electric field

Investigation of single molecule DNA dynamics in confined environments has led to important applications in DNA analysis, separation, and sequencing. Here, we studied the electrophoretic transport of DNA molecules through nanochannels shorter than the DNA contour length and calculated the associated translocation time curves. We found that the longer T4 DNA molecules required a longer time to traverse a fixed length nanochannel than shorter λ DNA molecules and that the translocation time decreased with increasing electric field which agreed with theoretical predictions. We applied this knowledge to design an asymmetric electric pulse and demonstrate the different responses of λ and T4 DNA to the pulses. We used Brownian dynamics simulations to corroborate our experimental results on DNA translocation behaviour. This work contributes to the fundamental understanding of polymer transport through nanochannels and may help in designing better separation techniques in the future.     

Developmental dyslexia in an orthography of intermediate depth: the case of European Portuguese

Fifteen Portuguese children with dyslexia, aged 9–11 years, were compared with reading and chronological age controls with respect to five indicators related to the phonological deficit hypothesis: the effects of lexicality, regularity, and length, implicit and explicit phonological awareness, and rapid naming. The comparison between groups indicates that Portuguese children with dyslexia have a phonological impairment which is revealed by a developmental deficit in implicit phonological awareness and irregular word reading (where younger reading level controls performed better than dyslexics) and by a developmental delay in decoding ability and explicit phonological awareness (where dyslexics matched reading level controls). These results are discussed in relation to the idea that European Portuguese is written in an orthography of intermediate depth.     

Key determinants of time to 5 m in different ventral swimming start techniques

The aim of this study was to determine the biomechanical parameters that explain ventral start performance in swimming. For this purpose, 13 elite swimmers performed different variants of the ventral start technique. Two-dimensional video analyses of the aerial and underwater phases were used to assess 16 kinematic parameters from the starting signal to 5?m, and an instrumented starting block was used to assess kinetic data. A Lasso regression was used to reduce the number of parameters, providing the main determinants to starting performance, revealing different combinations of key determinants, depending on the variant (r²?≥?0.90), with flight distance being the most relevant to all variants (r?≤??0.80; p?r?=??0.79; p?r?≤?0.61; p?r²?=?0.66) or block time and flight distance (r²?=?0.83). These data provide relevant contributions to the further understanding of the biomechanics of swimming starts as well as insights for performance analysis and targeted interventions to improve athlete performance.     

Have the poor found their own appropriate

Correspondence schools in Brazil are entirely in the hands of private entrepreneurs and ignored, even despised, by official educators. Yet, as this paper shows, they can, —in many cases, do—, provide helpful education for those who have no other access to educational opportunity. Indeed, they appear to offer the most equal form of opportunity. Accompanying their benefits, however, are many imperfections and abuses. The paper identifies five areas where government intervention could help both the public and the correspondence schools, without stifling their current vitality.     

Discrimination blocking: Acquisition versus performance deficits in human contingency learning

We compared acquisition and performance accounts of human contingency learning. After solving a discrimination in Phase 1, in which Cue A predicted the occurrence of the outcome and Cue B predicted its nonoccurrence (A+/B−), a new discrimination (X+/Y−) was superimposed in Phase 2 (AX+/BY−). The participants were finally trained in Phase 3 with the added discrimination, which either maintained the same contingencies as those in Phase 2 (X+/Y−; Experiment 1) or reversed the contingencies (X−/Y+; Experiment 2). According to competitive-learning theories (e.g., Rescorla & Wagner, 1972), there should be no learning of the added discrimination in Phase 2, so that no advantage or disadvantage for this discrimination should be observed in Phase 3. In contrast, performance theories, such as the comparator hypothesis (Miller & Matzel, 1988), contend that learning of the added discrimination in Phase 2 should proceed normally; so, in Phase 3, an advantage for the added discrimination should be observed in Experiment 1, but a disadvantage should be observed in Experiment 2. Our participants learned about the added discrimination and generally showed the effects predicted by the comparator hypothesis.     

An asset-based perspective on prospective teacher education

Journal of Mathematics Teacher Education -     

Resilience strategies for new teachers in high-needs areas

This qualitative study investigates strategies of resilience exhibited by fifteen novice teachers employed in high-needs areas, such as in urban and rural contexts and in special education. Findings indicated that teachers utilised a variety of strategies, including help-seeking, problem-solving, managing difficult relationships, and seeking rejuvenation/renewal. These strategies assisted beginning teachers in building additional resources and support; however, the burden for success and securing resources fell on teachers themselves. Furthermore, the researchers recognised that resilient teachers demonstrated agency in the process of overcoming adversity. Implications for future practice and research are discussed.     

Detection of Catabacter hongkongensis in polluted European water samples

The Catabacteriaceae is a new bacterial family with a unique member: Catabacter hongkongensis is a strictly anaerobic, non-sporulating, Gram-positive coccobacillus that is phylogenetically related to some clostridial clusters. Little is known of its epidemiology and environmental distribution, but the inclusion of its 16S rRNA gene sequence in GenBank has allowed it to be detected qualitatively. As a first approach for prospective surveys, a real-time polymerase chain reaction (PCR) procedure to identify C. hongkongensis has been developed. The presence of Catabacteriaceae in 29 water bodies subjected to possible human or animal impact has been investigated. Four of them were positive. The results confirm that highly polluted water can contain C. hongkongensis.