Low energy consumption is one of the main challenges for wireless video transmission on battery limited devices. The energy invested at the lower layers of the protocol stack involved in data communication, such as link and physical layer, represent an important part of the total energy consumption. This communication energy highly depends on the channel conditions and on the transmission data rate. Traditionally, video coding is unaware of varying channel conditions. In this paper, we propose a cross-layer approach in which the rate control mechanism of the video codec becomes channel-aware and steers the instantaneous output rate according to the channel conditions to reduce the communication energy. Our results show that energy savings of up to 30% can be obtained with a reduction of barely 0.1 dB on the average video quality. The impact of feedback delays is shown to be small. In addition, this adaptive mechanism has low complexity, which makes it suitable for real-time applications. 相似文献
The French orthographic code is complex, and its acquisition is laborious (Catach, 2008; Fayol & Jaffré, 2008). Three hypotheses attempt to explain orthographic knowledge acquisition (OKA). For some, exposure to the code leads to OKA through a self-learning process (Share, 2004). For others, OKA benefits from graphophonological processes (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001). Finally, some authors suggest that OKA is possible thanks to visual specific processes (Ans, Carbonnel, & Valdois, 1998). The main goal of this study was to test these hypotheses in a classroom context with comparable samples. In total, 143 2nd-grade children participated in this quasi-experimental study with a pretest, immediate posttest, and delayed posttest design. We assigned participants to one of four conditions. For three conditions, we created three teaching procedures based on each of the hypotheses: frequency of contacts with target words; explicit teaching of graphophonological properties of words; explicit teaching of visual properties of words. The fourth served as a control group. ANOVA analyses indicated that all three experimental conditions favored OKA, showing that the different teaching procedures led to spelling development. However, the visual condition was the most favorable. Three main conclusions can be drawn from this study: (a) models of OKA should account for the different paths that can lead to spelling acquisition; (b) visual properties of words and their acquisition need additional research, and (c) applied research in real classroom contexts is not only relevant for informing teaching practices but also for better understanding how learning takes place.
Various initiatives over the past 40 years have aimed to strengthen children’s early learning and social development. One policy theory—manifest in recent welfare reforms—postulates that requiring single mothers to work more outside the home will advance children’s well-being. We first examine whether young children’s social development is related to maternal employment among 405 women who entered welfare-to-work programs in 1998. For girls, age 24–42 months, we found that their mother’s recent employment duration was significantly associated with a lower incidence of aggressive behavior and inattentiveness, measured by two scales from the Child Behavior Checklist (CBCL 2/3). Yet these relationships with employment were weaker than more robust associations observed for proximal child-rearing practices, including the frequency of reading with the child, enforcing a regular bedtime, the propensity to spank the child, as well as levels of maternal depression. We then assess whether broader measures of the mother’s economic security help to predict these proximal determinants of development. We observed that food security and indicators of job quality consistently predicted the proximal factors. Structural equation models (SEM) provided additional evidence that these broader indicators of economic security, but not recent employment per se, operated through parenting practices and maternal depression to influence girls’ and boys’ social development. These results are consistent with recent findings from random-assignment experiments, showing that employment gains rarely affect child outcomes unless mothers’ income and broader economic security also improve. 相似文献
AN EXPLORATION OF THE EDUCATIONAL RESILIENCE OF TEACHING STAFF – This study focuses on the degree of resilience displayed
by teaching staff with the aim of promoting their professional development and preventing job-related exhaustion. Seven underprivileged
schools in Montreal were selected, and 24 teaching staff with contrasting personal profiles were interviewed on the subject
of their work. The Alceste software was used to analyse the conversations, which revolved around techniques applied when dealing
with critical incidents. The main analysis identified five different discourses among the respondents. Three of these were
associated with the more resilient of the teachers and two were associated with the more vulnerable ones. Resilient teaching
staff characteristically discussed dealing with aggressive behaviour, the teaching-learning relationship and the subject of
social relationships, whereas vulnerable teaching staff focused on work beyond the classroom, people in positions of higher
authority and the community. The authors note that teachers who are just embarking on their careers appear more vulnerable
than more experienced teaching staff, which suggests that more resources should be provided to support teachers in their profession. 相似文献
Autonomy-supportive parenting is found to foster children’s adjustment but relatively few studies have been conducted with toddlers. In the present exploratory study, parents (N = 182) reported what practices they use when asking their toddlers (M age = 26.9 months) to engage in important yet uninteresting activities. Parents rated twenty-six potentially autonomy-supportive practices, along with a well-known scale measuring the extent to which they have a positive attitude towards autonomy support. Research Findings: Using correlational and factorial analyses, eight practices were identified: various ways to communicate empathy, providing developmentally appropriate rationales, describing the problem in an informational and neutral way, and modeling the requested behavior. This subset of autonomy-supportive practices for toddlers was positively related with toddlers’ rule internalization, providing them with further validity. Practice or Policy: These preliminary findings may be useful in guiding future conceptual, empirical, and applied work on the support of toddlers’ autonomy and its assessment in an emotionally-charged and challenging context. 相似文献
An increasing number of scholars are being trained in the field of mind, brain, and education (MBE), yet discussions of trainees' needs and how to meet them are rare. We, the inaugural International Mind, Brain, and Education Society (IMBES) Trainee Board, identify three broad needs of MBE trainees: guidance and support, greater access to and connections among the MBE community, and professional development. We report a first step to address these needs: a daylong trainee conference, which included sessions to foster connections among trainees, provide mentorship from MBE leaders, and provide knowledge and skill building for careers. Attendees' survey results suggest the conference successfully supported trainees' development. As substantial trainee needs remain, we offer specific ways that principal investigators, institutions, funding agencies, future IMBES trainee boards, and the MBE community can further address trainees' needs to support early‐career development and strengthen the MBE field generally. 相似文献