Ergogenic effects of precooling with cold water immersion and ice ingestion: A meta-analysis

This review evaluated the effects of precooling via cold water immersion (CWI) and ingestion of ice slurry/slushy or crushed ice (ICE) on endurance performance measures (e.g. time-to-exhaustion and time trials) and psychophysiological parameters (core [T_core] and skin [T_skin] temperatures, whole body sweat [WBS] response, heart rate [HR], thermal sensation [TS], and perceived exertion [RPE]). Twenty-two studies were included in the meta-analysis based on the following criteria: (i) cooling was performed before exercise with ICE or CWI; (ii) exercise longer than 6?min was performed in ambient temperature ≥26°C; and (iii) crossover study design with a non-cooling passive control condition. CWI improved performance measures (weighted average effect size in Hedges’ g [95% confidence interval]?+?0.53 [0.28; 0.77]) and resulted in greater increase (ΔEX) in T_skin (+4.15 [3.1; 5.21]) during exercise, while lower peak T_core (?0.93 [?1.18; ?0.67]), WBS (?0.74 [?1.18; ?0.3]), and TS (?0.5 [?0.8; ?0.19]) were observed without concomitant changes in ΔEX-T_core (+0.19 [?0.22; 0.6]), peak T_skin (?0.67 [?1.52; 0.18]), peak HR (?0.14 [?0.38; 0.11]), and RPE (?0.14 [?0.39; 0.12]). ICE had no clear effect on performance measures (+0.2 [?0.07; 0.46]) but resulted in greater ΔEX-T_core (+1.02 [0.59; 1.45]) and ΔEX-T_skin (+0.34 [0.02; 0.67]) without concomitant changes in peak T_core (?0.1 [?0.48; 0.28]), peak T_skin (+0.1 [?0.22; 0.41]), peak HR (+0.08 [?0.19; 0.35]), WBS (?0.12 [?0.42; 0.18]), TS (?0.2 [?0.49; 0.1]), and RPE (?0.01 [?0.33; 0.31]). From both ergogenic and thermoregulatory perspectives, CWI may be more effective than ICE as a precooling treatment prior to exercise in the heat.     

In-season changes in ventricular morphology and systolic function in adolescent female athletes

Purpose: To evaluate the influence of physical maturity on the changes in ventricular morphology and function with sport training in female youth athletes.

Methods: Thirty-two female athletes (age 13–18 years) underwent height and weight measurement and 2-D echocardiographic evaluation immediately prior to, and following, a 20-week soccer season. Pre- and post-season left ventricular end-diastolic diameter (LVEDD), end-diastolic volume (LVEDV), ejection fraction (LVEF), stroke volume (LVSV), mass (LVM), and posterior wall thickness (LVPWT), right ventricular end-diastolic diameter (RVEDD), end-diastolic area (RVEDA), and fractional area change (RVFAC), and interventricular septal thickness (IVST) were compared. In-season change in each variable was compared across pre-season hours of vigorous physical activity (0–1, 2–3, >3 hours).

Results: Significant increases were identified in LVEDV (51.3?±?10.4?v 56.4?±?9.6?ml/m², p?=?0.001) and RVEDA (10.5?±?1.9?v 11.3?±?2.5?cm²/m², p?=?0.040), but not LVEDD, LVM, LVPWT, LVSV, RVEDD, RVEDA, RVFAC, or IVST (p?>?0.05 for all). In-season changes in echocardiographic variables did not differ across hours of pre-season vigorous physical activity (p?>?0.05 for all).

Conclusion: Among female adolescent soccer players, in-season training elicits changes in resting ventricular volume, but not wall thickness or systolic function. These adaptations do not appear to be influenced by pre-season physical activity level.     

Taking risks with a growth mindset: long-term influence of an elementary pre-service after school science practicum

In this study, we present the long-term influence of an after school science practicum associated with an elementary science methods course. The practicum or field experience could be considered a community-based service learning programme as it is situated both within and for the community. Study participants included eight third- and fifth-grade teachers who had participated in elementary science methods courses; four of these teachers participated in the after school teaching practicum while four participants experienced a more traditional observation-based elementary science practicum. All of these teachers were in their second or third year teaching which was 3–4 years after taking the methods course. Investigation methods included questionnaires, field observations and semi-structured, individual interviews. Teachers more regularly utilised reform-based teaching strategies and cited the after school teaching practicum as preparing them to use these strategies in their own classrooms. All teachers exhibited a growth mindset to some degree, but the after school practicum participants did demonstrate a wider use of reformed-based teaching strategies and a higher growth mindset. Elementary teachers perceive risk associated with these key aspects of instruction: (1) managing instruction and classroom management, (2) teaching science through guided inquiry, and (3) overcoming adoptions in other ‘mandated’ curriculum like math and reading.     

Cooperative Governance of Successful Public Schooling: Successes,Frustrations and Challenges

In search of embodying values that underpin democracy at school level, the objectives of the article include exploring expectations generated by the constitutional dispensation (Constitution of the Republic of South Africa, 108/1996, section 41) and delineating those moulded by the South African Schools Act (84/1996, Preamble). While the latter formally signify a State-education-partnership, the intention for teachers, learners and parents to accept especially governance responsibilities towards school democracy prompted our focused three-way alliance between parent-teacher-learner parties for the purpose of this article. Our conceptual framework is informed by Permuth, Mawdsley and Silver (2015), who contend that the essentially new facet of moving towards integrating qualitative research with doing traditional legal research could expand legal reasoning and even complement it with empirical credibility. Authenticated by Adler (2015), the article therefore combines focusing on cooperative governance as an act to shape schooling in the traditional legal way (by asking what questions) with qualitative research features to inform us by also asking how and why questions. We chose a documentary design with a comparative angle; selected documentary resources; and took an exploratory approach to gain understanding and weigh the investigated documents by comparing and appraising primary and secondary sources. We also regarded whatever was embedded yet not recorded as similarly important to what was recorded and how a specific concept was extended (De Waal and Serfontein 2015). Reviewing relevant case law, we present an overview of cooperative school governance progress; a constitutional challenges-based intervention; continuous acceptance of responsibility and accountability; and successes, frustrations and challenges concerning the future pathway to successful schooling. Given the snowballing set of demands on public schools, the catch is for partners to know each other's strengths and weaknesses so that balanced contributions will cause governance towards quality education. The drastic parental governance and leadership role-change, with higher moral-social responsibility levels, calls for carefully designed conferences to guide parent-partners’ exercising the necessary discretion underpinned by critically considering the significance of serving society.     

An investigation into the complex process of facilitating effective professional learning: CPD tutors’ practices under the microscope

Background: Research evidence on what makes CPD effective is accumulating. Yet, fundamental questions about the specific features that lead to programme success. Furthermore, very little research investigates the nature and quality of CPD providers’ (tutors) practices. Taking a closer look at how CPD providers support teachers to learn is therefore an important direction for research in order to offer specific guidance on how to design and deliver future CPD programmes for maximum impact.

Purpose: The present study aimed to advance this line of inquiry by seeking to examine tutors’ perceptions and practices in the context of a short course on Inclusive Physical Education. Two research questions were addressed: (1) What were the tutors’ perceptions of effective CPD delivery? And (2) How were these interpretations evidenced in practice? The short course, delivered by 40 different tutors across the country, was part of a National CPD programme which reached and educated over 5000 school staff in England. The scale of this programme thus offered an ideal setting in which to address the research questions.

Participants and setting: A case study design was adopted where the case was identified at the level of individual courses. A cluster sampling procedure was adopted (one cluster for each of the nine geographical areas in England). Where possible, systematic sampling within the nine clusters was employed (i.e. collect evidence from the first two courses delivered in each cluster each year). A total of 27 courses, delivered by 20 tutors across eight geographical areas in England, were selected as cases and all tutors involved in their delivery were invited to participate in the study.

Data collection: To explore tutors’ perceptions of effective CPD delivery (research question 1), qualitative data were collected via an online questionnaire and individual interviews. To examine how these interpretations were evidenced in practice (research question 2), both quantitative and qualitative data were collected via systematic observations and ethnographic field notes.

Data analysis: Qualitative data were analysed using a constructivist approach to grounded theory. Quantitative data from the observations were entered into SPSS version 21 (IBM Statistics) for analysis.

Findings: Findings indicate that tutors’ perceptions and beliefs did not always materialise. Data from the observations suggest variation in the ways tutors structured, supported and facilitated professional learning. This variation was evident not only in the actual time dedicated to practical vs. theoretical activities and active vs. passive learning opportunities but also in tutors’ ability to facilitate professional learning. This finding suggests that there is a significant set of skills involved in supporting, nurturing and challenging professional learning in CPD contexts. It is therefore important to consider how tutors can be best supported to develop and implement these skills effectively.

Conclusion: The results consolidate existing understandings about the importance of (inter)active and practical learning opportunities in CPD; but also add nuance and detail on the diverse ways in which tutors engaged participants in the learning process. Findings draw our attention to the important issue of the selection and continuing education of CPD tutors.     

NTP同步算法在校园网中的应用

时间同步技术是现代网络应用的关键技术,针对高校校园网络设备对时间准确可靠性的要求,在传统NTP同步算法的基础上构建基于C/S模式的网络时间同步系统应用到校园局域网中.通过测试验证该同步算法系统能够在现时环境中满足校园网对时间精确度的需求.     

PI3K阻断剂对大鼠运动骨骼肌Akt/mTOR信号的影响

目的:通过阻断PI3K信号,以深入探讨Akt/mTOR通路在抗阻运动中骨骼肌蛋白合成的作用。方法:8周龄雄性SD大鼠在适应性训练后分为4组:安静组(S)、阻断剂组(SL)、运动组(E)、运动+阻断剂组(EL),每组6只。运动方式为跑台运动(坡度为10%,跑速20 m/min,60 min),每天1次,共7 d。腹腔注射外源性LY294002(剂量为5.5 mg/kg)。用Western Blotting法检测腓肠肌MHC、Akt和mTOR蛋白表达、Akt(Ser473)和mTOR(Ser2448)磷酸化表达。结果:在一周后,LY294002明显抑制MHC,运动有促进的趋势,并减弱LY294002对MHC的抑制效应。LY294002显著抑制Akt和mTOR蛋白表达、Akt(Ser473)和mTOR(Ser2448)的磷酸化表达,而运动明显增强mTOR、Akt(Ser473)和mTOR(Ser2448)表达。结论:1)阻断PI3K信号可使运动骨骼肌Akt/mTOR通路受到明显抑制,而同时骨骼肌MHC明显降低,明显抑制肌肉蛋白合成。2)运动明显促进该通路的表达,并减弱PI3K阻断剂对该通路的抑制效应。3)PI3K阻...     

icl7135的串行采集方式在蓄电池电压监测系统中的应用

文章介绍了双积分型a/d转换器icl7135的串行数据采集方式在蓄电池电压监测系统中的应用,给出了icl7135与mcs-51单片机串行接口实现电压监测硬件和软件设计方法.     

基于Pro／TOOLKIT的齿轮快速设计系统的研究与开发

针对齿轮结构复杂,直接使用Pro/E造型困难、工作量大、效率低的特点,基于Pro／E平台,运用二次开发工具Pro／TOOLKIT研究与开发了齿轮快速设计系统。用户通过友好的界面输入齿轮设计基本参数,即可自动生成齿轮的三维实体,从而缩短产品开发周期,提高设计效率。     

太阳光下La~(3+)掺杂TiO_2纳米粒子光催化降解亚甲基蓝的动力学研究

利用酸催化的快速溶胶-凝胶法(sol-gel)制备了一系列不同La3+掺杂量(x=0.01%～3%)的TiO2复合光催化剂;在太阳光条件下,以亚甲基蓝溶液的光催化降解为模型反应,研究了染料的光催化降解动力学行为,考察了催化剂投加量和La3+掺杂量对复合光催化剂活性的影响.结果表明,亚甲基蓝的光催化降解反应遵循Langmuir-Hinshelwood动力学模型,表观反应速率常数随着反应体系中催化剂用量和La3+掺杂量的不同而不同,均存在一个最佳值.在本实验条件下,当催化剂投加量为1.5g/L,La3+掺杂量为0.5%时,测得表观反应速率常数为2.1.×10-2mg(L·min)-1,反应120min后亚甲基蓝的降解率可达91.55%.