Does modality matter? A latent profile and transition analysis of sedentary behaviours among school-aged youth: The UP&DOWN study

ABSTRACT

The aims of this study were to identify profiles of sedentary behaviour (SB) patterns, based on leisure-time self-reported SB modalities (screen, educative, social, and relaxing) and to evaluate changes in these profiles over 2 years among Spanish youth aged 8–18 years. Latent profile analysis (LPA), a data-driven analytic approach, was used to identify groups of boys and girls (n = 1553; 48% girls; mean±SD age: 12.56 ± 2.49 y) with distinct SB profiles using the SB modalities (time/d) as input variables. Latent transition analysis, an extension of LPA that uses longitudinal data, was used to analyse 2-year changes in these profiles. At baseline, four and three SB profiles were found among boys (labelled: screen, educative, social, and relaxing) and girls (labelled: screen/social, educative, and relaxing), respectively. Overall, more girls (range: 48%-67%) had the same profile over time, than boys (40%-52%). Participants with a screen or relaxing SB profile at baseline were more likely to have an educative profile after 2 years. Youth with a social and an educative SB profile at baseline were more likely to transition to profiles characterized by higher screen and social SB, respectively. Using a novel and person-centered approach, this study identified gender-specific SB profiles that were moderately stable over time.     

Medieval and renaissance glass technology in Valdelsa (Florence). Part 1: raw materials, sands and non-vitreous finds

A significant number of archaeological finds of the 13th–16th century from the Tuscan sites of Germagnana and Gambassi in Valdelsa—FI, was studied by different physico-chemical investigations (SEM–EDS, ICP, Mössbauer spectroscopy, XRD, XRF, TG-DTA) in order to contribute to clarify the production methodology and the pre-industrial glass manufacture technology. The studied samples are mainly non-vitreous finds as production waste, refractory materials, crucibles and raw materials; also vitreous finds as frits, skims, glasses (glass masses, glass working waste and finished products) have been taken into consideration. The obtained petrographic and physico-chemical data strongly suggest that both Gambassi and Germagnana glass manufactures were strictly connected with the sources of vitrifiable materials, situated in Tuscan sand quarries. In particular a comparison between sands from the neighbouring quarries and appropriate finds of the two archaeological sites evidences that the employed vitrifiable materials possibly belong to La Casina La Cava resort. The archaeological classification, based on macroscopic observation and stratigraphic position, was compared and verified with the scientific classification of the examined finds of Germagnana and Gambassi sites based on their composition, morphology and physico-chemical properties.     

时代特征与马克思主义的理论形态

150多年来，马克思主义随着人类历史的发展和时代课题的解决，在实践中形成了新的形态，使马克思主义成为与时俱进的普遍真理，使社会主义在曲折中不断向前发展，成为人类社会发展不可逆转的总趋势。     

银杏化学成分及药理作用的研究和应用进展

银杏（Gimkgo biloba）又名白果树，为银杏科，银杏属植物。银杏具有多种化学成分、毒性成分和有效成分，银杏中有效成分的药理作用促进了银杏有效成分分离提取技术的研究。我国银杏制剂研究开发在经历了一哄而上的局面后已逐步走向成熟和规范。     

教师专业化背景下反思型体育教师培养模式

教师的专业化发展要求教师成为反思型教师,而反思型教师的成熟和发展离不开教育实践的锻炼和促进,只有将实践中反映出来的问题上升到理论层面加以反思,才能探寻到根源,使主体的合理性水平得到提升和拓宽.体育教师要坚持积极的自我反思与实践,以主体身份投入其中,扩大自己的专业视野,逐步养成教育反思的习惯,建立自我反思机制,成为反思型教师,同时促进教师专业化发展.     

人体体成份检测方法

通过文献法对国内外现有的人体体成份检测方法发展状况进行概述,显示:人们对人体组成成份的研究随着近年来检测仪器和设备的迅速发展而进一步深入,测量结果也越来越精确。     

高住低训对运动员身体成分的影响

为了确切了解运动员在高住低训过程中身体成分的变化,本研究将14名大学生分为:高住低训组(HiLo组)和高住对照组(Hi c组),每组7人,每天低压低氧(2500m模拟高度)暴露12小时。HiLo组每天在常压常氧环境下进行一次3000m跑训练;Hi c组在实验期间不进行任何运动训练。实验为期4周。结果表明,高住低训组体重、体脂重量和体脂百分比明显下降(P<0 05),其他指标稍有降低,但变化不明显(P>0 05)。高住对照组体重、体脂重量、体脂百分比明显下降(P<0 05),其他指标几乎没有变化。模拟高住低训组和高住对照组体重明显降低,瘦体重和肌肉重量无明显变化,而体脂重量和体脂百分比明显降低,说明体重的降低是体脂重量降低的结果。本实验采用的高住模型对蛋白分解作用无明显影响,但机体却选择性利用脂肪供能。而2500m间歇低氧暴露结合训练具有轻微的促蛋白分解效应。     

构建高校三级跳远运动员训练模式探究

在多年实践的基础上 ,对高校三级跳远运动员的训练进行剖析 ,确认训练应以技术训练为核心 ,以运动员个人特点为训练基础 ,以及正确处理力量素质训练与技术训练的关系 ,技术训练中的负荷问题 ,提出适合高校三级跳远训练的模式 ,并进行了理论上的探索     

高师高等数学课的几种课型设计

针对高等数学课程教学的不足设计了三种行之有效的课型,并给出了它们的应用.     

体育专业计算机教育中的教学模式研究

基于计算机基础教育是素质教育的认识,研究了体育与计算机教育的教与学的模式.着重讨论了体育与计算机教育的教与学中的一些重要手段:四年的教育不断线,模块化的教学方法,多功能的教学环境等.