Evaluating the Power of Latent Growth Curve Models to Detect Individual Differences in Change     

Christopher Hertzog  Timo von Oertzen  Paolo Ghisletta  Ulman Lindenberger 《Structural equation modeling》2013,20(4):541-563

We evaluated the statistical power of single-indicator latent growth curve models to detect individual differences in change (variances of latent slopes) as a function of sample size, number of longitudinal measurement occasions, and growth curve reliability. We recommend the 2 degree-of-freedom generalized test assessing loss of fit when both slope-related random effects, the slope variance and intercept-slope covariance, are fixed to 0. Statistical power to detect individual differences in change is low to moderate unless the residual error variance is low, sample size is large, and there are more than four measurement occasions. The generalized test has greater power than a specific test isolating the hypothesis of zero slope variance, except when the true slope variance is close to 0, and has uniformly superior power to a Wald test based on the estimated slope variance.  相似文献   

Editorial     

Christopher Day Editor 《Teachers and Teaching》2013,19(6):587-589

This article discusses the advantages and disadvantages of using information and communication technology (ICT) as a mediating artefact in the classroom compared to alternative tools with illustrations from a qualitative classroom study. The aim of the article is to describe and show the conditions that have to be satisfied if ICT is to have an advantage over alternative tools in a classroom. The main focus is on the importance of the context of the learning activities, in which the teacher plays an important part. Theories on language and learning are presented and the article concludes with reflections on the teacher’s role in the use of ICT in the classroom.  相似文献   

Peer mentoring for first‐year teacher education students: the mentors’ experience     

Ann M. Heirdsfield  Sue Walker  Kerryann Walsh  Lynn Wilss 《Mentoring & Tutoring: Partnership in Learning》2013,21(2):109-124

Universities worldwide are developing peer mentoring programmes to assist first‐year students’ transition into university life. Awareness of the mentees’ experiences in the mentoring programme – the successes and challenges – contributes to ongoing planning for successful transition for first‐year students. Also, understanding the mentors’ experiences can contribute to the success of the programme and, more importantly, can lead to strong self efficacy for the mentors. This qualitative study appraises a mentoring programme for first‐year undergraduate students from the mentors’ perspective. The mentors’ experiences, both positive and negative, are discussed and a relational model of mentoring is presented. The results of this inquiry have implications for the development of future mentoring programmes, particularly in terms of mentor recruitment and preparation, if first‐year students are to be effectively oriented and supported in their transition to university study.  相似文献   

A modular cell culture device for generating arrays of gradients using stacked microfluidic flows     

Sip CG  Bhattacharjee N  Folch A 《Biomicrofluidics》2011,5(2):22210

Microfluidics has become increasingly important for the study of biochemical cues because it enables exquisite spatiotemporal control of the microenvironment. Well-characterized, stable, and reproducible generation of biochemical gradients is critical for understanding the complex behaviors involved in many biological phenomena. Although many microfluidic devices have been developed which achieve these criteria, the ongoing challenge for these platforms is to provide a suitably benign and physiologically relevant environment for cell culture in a user-friendly format. To achieve this paradigm, microfluidic designs must consider the full scope of cell culture from substrate preparation, cell seeding, and long-term maintenance to properly observe gradient sensing behavior. In addition, designs must address the challenges associated with altered culture conditions and shear forces in flow-based devices. With this consideration, we have designed and characterized a microfluidic device based on the principle of stacked flows to achieve highly stable gradients of diffusible molecules over large areas with extremely low shear forces. The device utilizes a benign vacuum sealing strategy for reversible application to pre-established cell cultures. We apply this device to an existing culture of breast cancer cells to demonstrate the negligible effect of its shear flow on migratory behavior. Lastly, we extend the stacked-flow design to demonstrate its scalable architecture with a prototype device for generating an array of combinatorial gradients.  相似文献   

Ventilatory acclimatisation is beneficial for high-intensity exercise at altitude in elite cyclists     

Nathan E. Townsend  Christopher J. Gore  Tammie R. Ebert  David T. Martin  Allan G. Hahn  Chin-Moi Chow 《European Journal of Sport Science》2016,16(8):895-902

Aim: The aim of this study was to examine the relationship between ventilatory adaptation and performance during altitude training at 2700?m. Methods: Seven elite cyclists (age: 21.2?±?1.1?yr, body mass: 69.9?±?5.6?kg, height 176.3?±?4.9?cm) participated in this study. A hypoxic ventilatory response (HVR) test and a submaximal exercise test were performed at sea level prior to the training camp and again after 15 d at altitude (ALT15). Ventilation (V_E), end-tidal carbon-dioxide partial pressure (P_ETCO₂) and oxyhaemoglobin saturation via pulse oximetry (SpO₂) were measured at rest and during submaximal cycling at 250?W. A hill climb (HC) performance test was conducted at sea level and after 14 d at altitude (ALT14) using a road of similar length (5.5–6?km) and gradient (4.8–5.3%). Power output was measured using SRM cranks. Average HC power at ALT14 was normalised to sea level power (HC%). Multiple regression was used to identify significant predictors of performance at altitude. Results: At ALT15, there was a significant increase in resting V_E (10.3?±?1.9 vs. 12.2?±?2.4?L·min^?1) and HVR (0.34?±?0.24 vs. 0.71?±?0.49?L·min^?1·%^?1), while P_ETCO₂ (38.4?±?2.3 vs. 32.1?±?3.3?mmHg) and SpO₂ (97.9?±?0.7 vs. 94.0?±?1.7%) were reduced (P?V_E at altitude as significant predictors of HC% (adjusted r²?=?0.913; P?=?0.003). Conclusions: Ventilatory acclimatisation occurred during a 2 wk altitude training camp in elite cyclists and a higher HVR was associated with better performance at altitude, relative to sea level. These results suggest that ventilatory acclimatisation is beneficial for cycling performance at altitude.  相似文献   

The development of uncertainty monitoring during kindergarten: Change and longitudinal relations with executive function and vocabulary in children from low-income backgrounds     

Christopher R. Gonzales  Alexis Merculief  Megan M. McClelland  Simona Ghetti 《Child development》2022,93(2):524-539

Children's ability to monitor subjective feelings of uncertainty (i.e., engage in uncertainty monitoring) is a central metacognitive skill. In the current study, we examined the development of uncertainty monitoring as well as its relations with vocabulary and executive function development in children (N = 137, 52% female) from predominately White and Latinx/Hispanic backgrounds when they were 4–6 years old and enrolled in a Head Start preschool and kindergarten between 2018 and 2019. We found that children's uncertainty monitoring improved during the kindergarten year. Children's executive function and vocabulary in preschool and vocabulary growth from preschool to kindergarten predicted uncertainty monitoring at the end of kindergarten, which sheds new light on potential mechanisms supporting children's metacognitive development.  相似文献   

High School Success: A Learning Strategies Intervention to Reduce Drop-Out Rates     

Lowder  Christopher  O’Brien  Chris  Hancock  Dawson  Hachen  Jeremy  Wang  Chuang 《The Urban Review》2022,54(4):509-530

The Urban Review - The transition into high school is a critical time to act for students with a history of academic difficulty. In this study, researchers examined the impact of a learning...  相似文献   

Growth in written academic word use in response to morphology-focused supplemental instruction     

Wood  Carla  Schatschneider  Christopher 《Reading and writing》2022,35(2):399-426

Reading and Writing - The aims of the current project were to: (1) describe average change in the use of academic words across the school year in writing and (2) examine potential predictors of...  相似文献   

Micro- and nanofluidic technologies for epigenetic profiling     

Toshiki Matsuoka  Byoung Choul Kim  Christopher Moraes  Minsub Han  Shuichi Takayama 《Biomicrofluidics》2013,7(4)

This short review provides an overview of the impact micro- and nanotechnologies can make in studying epigenetic structures. The importance of mapping histone modifications on chromatin prompts us to highlight the complexities and challenges associated with histone mapping, as compared to DNA sequencing. First, the histone code comprised over 30 variations, compared to 4 nucleotides for DNA. Second, whereas DNA can be amplified using polymerase chain reaction, chromatin cannot be amplified, creating challenges in obtaining sufficient material for analysis. Third, while every person has only a single genome, there exist multiple epigenomes in cells of different types and origins. Finally, we summarize existing technologies for performing these types of analyses. Although there are still relatively few examples of micro- and nanofluidic technologies for chromatin analysis, the unique advantages of using such technologies to address inherent challenges in epigenetic studies, such as limited sample material, complex readouts, and the need for high-content screens, make this an area of significant growth and opportunity.  相似文献   

The Meaning of Graceful Movement     

Christopher Cordner 《体育哲学杂志》2013,40(2):132-143

  相似文献