The suitability of Sanders’ model for calculation of the propulsive force generated by the hands during sculling motion

This study examined whether Sanders’ model is suitable for estimating accurately the propulsive force generated by the hands’ motion in swimming comparing the calculated force obtained using the model and the measured force during an actual propulsive action. The measured and calculated forces were obtained from 13 swimmers who, while tethered, performed a sculling motion in a prone position for the purpose of displacing the body by moving it forward. Kinematic analyses were conducted to obtain the calculated force, while the measured force was obtained via the use of a load cell. The calculated force was lower than the measured force and accounted for only a small part of the variation in the measured force. The forces could not be used interchangeably, and there were fixed and proportional differences between them. Consequently, this study indicates that Sanders’ model is not suitable for estimating accurately the propulsive force generated by the swimmer’s hands during sculling motion. However, research that integrates analyses from different approaches could result in improvements to the model that would render it applicable for estimating the propulsive forces during movements that are characterised by directional changes of the hands.     

Construction by dielectrophoresis of microbial aggregates for the study of bacterial cell dormancy

A study of the effect of aggregate size on the resuscitation of dormant M. smegmatis was conducted by constructing cell aggregates with defined sizes and shapes using dielectrophoresis and monitoring the resuscitation process under controlled laboratorial conditions in a long-term cell feeding system. Differently sized cell aggregates were created on the surface of indium tin oxide coated microelectrodes, their heights and shapes controlled by the strength of the induced electric field and the shape of the microelectrodes. Both two-dimensional (ring-patterned) and three-dimensional cell aggregates were produced. The cell aggregates were maintained under sterile conditions at 37 °C for up to 14 days by continuously flushing Sauton’s medium through the chamber. Resuscitation of dormant M. smegmatis was evaluated by the production of the fluorescent dye 5-cyano-2,3-ditolyltetrazolium chloride. The results confirm that the resuscitation of dormant M. smegmatis is triggered by the accumulation of a resuscitation promoting factor inside the aggregates by diffusion limitation.     

Typology of motivation and learning intentions of users in MOOCs: the MOOCKNOWLEDGE study

Educational technology research and development - Participants in massive open online courses show a wide variety of motivations. This has been studied with the elaboration of classifications of...     

Applying the PEN-3 Cultural Model to Address HIV/AIDS Prevention in Rural Guatemala

Guatemala has an accelerating HIV rate, where prevalence is three times higher among indigenous than nonindigenous, comprising 21% of all cases. Vulnerability is exacerbated by high poverty, low literacy, and poor access to testing and treatment options. This study develops a community-engaged HIV prevention campaign plan for the Mayan town of Santiago Atitlán. The PEN-3 model of cultural sensitivity frames this formative research project. Assessment domains of the PEN-3 model (Cultural empowerment and Relationships & expectations) identify culturally relevant factors affecting HIV prevention behaviours. The Cultural identity domain is utilized to identify entry points enhancing cultural acceptance and efficacy.     

Creativity: a challenge for contemporary education

ABSTRACT

In this essay, I comment on the objective of cultivating creativity in general and in schools in particular. I start by tracing the historical origin of this objective, then discuss a select set of relevant issues, including what can be considered the best practices for achieving this. I conclude by contemplating the potential for globalisation of this objective, and the portability of general pedagogies and specific approaches to cultivating creativity between different educational systems.     

空间均匀低温氢气燃烧器开发（英文）

目的:设计制造低温的催化氢气燃烧器,并对其进行相关功能性测试。创新点:成功设计并制造出一个集成流量分配器的催化低温氢气燃烧器。方法:1.基于树状分叉方法,设计燃烧器的流量分配器,均匀分配气体到催化表面,并利用熔融沉积成型技术制备原型样机。2.基于测试结果,利用选择性激光熔化技术对燃烧器进行最优化设计。3.对设计的催化燃烧器的相关功能进行验证。结论:1.设计的低温催化燃烧器与传统的非催化燃烧器相比具有很多优势,尤其是实现了无焰均匀低温(约200°C)的产热;这一技术有望运用于化工领域的增材制造。2.本文不但用选择性激光熔融技术制备了最终产品,而且利用了熔融沉积成型技术进行快速的样机制备。3.催化剂多孔载体的调控和催化剂的负载方式研究有望进一步提升燃烧器的综合性能。     

Separation by dielectrophoresis of dormant and nondormant bacterial cells of Mycobacterium smegmatis

The dielectrophoretic behavior of active, dead, and dormant Mycobacterium smegmatis bacterial cells was studied. It was found that the 72-h-old dormant cells had a much higher effective particle conductivity (812±10 μS cm⁻¹), almost double that of active cells (560±20 μS cm⁻¹), while that of dead (autoclaved) M. smegmatis cells was the highest (950±15 μS cm⁻¹) overall. It was also found that at 80 kHz, 900 μS cm⁻¹ dead cells were attracted at the edges of interdigitated castellated electrodes by positive dielectrophoresis, but dormant cells were not. Similarly, at 120 kHz, 2 μS cm⁻¹ active cells were attracted and dormant cells were not. Using these findings a dielectrophoresis-based microfluidic separation system was developed in which dead and active cells were collected from a given cell suspension, while dormant cells were eluted.     

Short-term optimal load training vs a modified complex training in semi-professional basketball players

This study investigated the effects on neuromuscular performance of a 6-week Optimal Load Training (OLT) and a novel modified Complex Training (MCT) (complex pairs: the same exercise using a moderate and an OL) in basketball players, in-season. Eighteen male athletes were randomly assigned to one of the protocols. Anthropometric measurements were taken to evaluate body composition. Lower- and upper-body maximum dynamic strength, countermovement jump (CMJ), standing long jump (SLJ), 10-m sprint and change of direction (COD) were also assessed. Moderate-to-large strength gains (presented as percentage change ± 90% confidence limits) were obtained for half-squat (OLT: 10.8 ± 5.3%; MCT: 17.2 ± 11.6%) and hip thrust (OLT: 23.5 ± 17.7%; MCT: 28.2 ± 19.0%). OLT athletes achieved likely small improvements in sprint (1.6 ± 1.6%) and COD (3.0 ± 3.2%). Players in the MCT attained likely moderate improvements in COD (3.0 ± 2.0%) and possibly small in SLJ (2.5 ± 4.6%). No protocol relevantly affected CMJ or body composition. An ANCOVA test revealed unclear between-group differences. In conclusion, both protocols increased basketball players’ strength without the use of heavy loads (> 85% 1RM) and without impairing sprint, CMJ and SLJ performance. These findings suggest that basketball strength and conditioning professionals may use either method to counteract strength losses during the season.     

Development of a cultural self-efficacy scale for adolescents (CSES-A)

We developed a cultural self-efficacy scale for adolescents (CSES-A) and tested its psychometric properties using both exploratory and confirmatory factor analyses. Cultural self-efficacy (CSE) was defined as person's perception of his/her own capability to function effectively in situations characterized by cultural diversity. On the basis of Bandura's guideline for the development of a domain-specific self-efficacy measure, we tailored 50 items after reviewing literature about cultural competence, adolescents’ school-problems and social self-efficacy scales developed in previous studies in intercultural contexts. After pre-testing and analyzing psychometric properties of the scale, we selected 33 items. Eight hundred sixty-eight adolescents with five different cultural origins completed a set of questionnaires, including the CSES-A, internal control expectancies, general self-efficacy, academic expectancies, number of people from diverse cultures they keep in touch with, acculturation attitudes, perceived enrichment of other cultures, acculturation stress and demographic data. An EFA with MPLUS 2.14 highlighted a five-factor solution with 25 items that was supported by a subsequent CFA. The five factors were: self-efficacy in mixing satisfactorily with other cultures, in understanding different ways of life, in processing information from other cultures, in coping with loneliness and in learning and understanding other languages. The pattern of correlation with internal control expectancies, general self-efficacy and cultural variables supported the validity of the scale. CSES-A may be useful for future research on multicultural contexts, in which self-efficacy in cultural adaptation could be a fundamental variable.     

Conservation of historical reinforced concrete structures damaged by carbonation induced corrosion by means of electrochemical realkalisation

Electrochemical realkalisation is a technique aimed at stopping rebar corrosion in carbonated concrete. The alkalinity of the concrete around the rebars is restored, and an environment favourable to the passivation of steel is re-created. The technique is based on the application of a DC current from an anode, placed on the external surface of the concrete, and the rebar. The anode is usually embedded in cellulose pulp soaked with a solution of sodium or potassium carbonate. The rebar and the anode are connected to a DC current feeder, the rebar to the negative terminal and the anode to the positive terminal. The applied current produces alkalinity at the surface of the rebar, while the alkaline electrolyte in which the anode is immersed penetrates from the external surface. In this way the concrete is realkalised, its protective characteristics towards the steel are restored and rebars can return to passive conditions. The treatment is temporary: this feature makes it very attractive in the field of historical buildings and cultural heritage, where the conservation of the original materials and surfaces is often a stringent requirement in the design of the repair. This paper shows the advantages of this technique applied to historical structures by describing the application to a bell tower built in the 1920s. The electrochemical realkalisation treatment was applied to eight columns on the bell tower where a traditional repair (based on the substitution of carbonated concrete with a repair mortar) would have been practically impossible. The application of the treatment followed two steps: initially, a trial was made on two sections of two columns, so as to calibrate the process parameters such as current density, time length and type of anode. Subsequently, the treatment was applied to all the columns. The analyses carried out on the concrete after the application of the treatment showed that the protection to the reinforcement was mainly connected to the alkaline layer produced around the steel, which is expected to prevent further corrosion of the steel.