Dual-hop relaying communications over generalized-K (KG) fading channels

In this paper, a study on the end-to-end performance of dual-hop non-regenerative relaying over independent generalized-K (KG) fading channels is presented. Using a suitable upper bound for the end-to-end signal-to-noise ratio (SNR), novel closed-form expressions for the cumulative distribution function (CDF), probability density function (PDF) and the moments of this bounded SNR are derived. These results can be afterwards used to obtain important performance metrics of the considered system such as the outage probability and the error performance of digital modulation schemes. In the case of independent but non-necessarily identical fading channels, lower bounds for the average bit error probability (ABEP) for different modulation schemes are determined by using the Padé approximants method. For the case of identical fading channels, closed-form lower bounds for the ABEP are derived. Various numerical and computer simulation results illustrate the proposed analysis.     

Snow White in Hellenic primary classrooms: children’s responses to non-traditional gender discourses

This paper sets out to investigate how children make sense of and negotiate non-traditional gender discourses promoted through the feminist version of the fairytale of Snow White. The research was based on work with 120 pupils aged 9–11 years old in 2 Athenian primary schools. The data were collected through semi-structured group interviews. The findings suggested that schoolchildren gave conflicting accounts in relation to gender discourses and identities. There is a strong indication that girls of this age are more prepared than boys to challenge traditional gender discourses.     

Assessment of energy expenditure in children using the RT3 accelerometer

The aim of this study was to evaluate the utility of the RT3 accelerometer in young children, compare its accuracy with heart rate monitoring, and develop an equation to predict energy expenditure from RT3 output. Forty-two volunteers (mean age 12.2 years, s = 1.1) exercised at two horizontal and graded walking speeds (4 and 6 km.h(-1), 0% grade and 6% grade), and one horizontal running speed (8 km.h(-1), 0% grade), on a treadmill. Energy expenditure and oxygen consumption (VO2) served as the criterion measures. Comparison of RT3 estimates (counts and energy expenditure) demonstrated significant differences at 4, 6, and 8 km.h(-1) on level ground (P < 0.01), while no significant differences were noted between horizontal and graded walking at 4 and 6 km.h(-1). Correlation and regression analyses indicated no advantage of vector magnitude over the vertical plane (X) alone. A strong relationship between RT3 estimates and indirect calorimetry across all speeds was obtained (r = 0.633-0.850, P < 0.01). A child-specific prediction equation (adjusted R2 = 0.753) was derived and cross-validated that offered a valid energy expenditure estimate for walking/running activities. Despite recognized limitations, the RT3 may be a useful tool for the assessment of children's physical activity during walking and running.     

Young people’s relationship to education: the case of Greek youth

The aim of this study is to explore how Greek youth understands their relationship to education, and how this understanding might change as a result of the interplay between participation in different educational/social arrangements and structural factors such as gender, socio‐economic background and area of residence. In total, 800 young people (i.e. four groups—students in upper‐secondary school, tertiary education, vocational education and training and working young people) were surveyed. The results yield an impressive homogeneity of the young people’s views corresponding to a ‘pragmatic’ image of schooling, though they are partially differentiated with respect to attitudes and practices. Moreover, boundaries are discerned between the young people following academic and non‐academic educational trajectories, and between the learning opportunities provided within and outside the formal educational system. Finally, females appear to be more mobilized, but less satisfied by educational services. These findings are contextualized and discussed against a background of relevant trends in other European countries, as well as of wider social, historical and political forces affecting Greek society.     

Towards an Analysis of Visual Images in School Science Textbooks and Press Articles about Science and Technology

This paper aims at presenting the application of a grid for the analysis of the pedagogic functions of visual images included in school science textbooks and daily press articles about science and technology. The analysis is made using the dimensions of content specialisation (classification) and social-pedagogic relationships (framing) promoted by the images as well as the elaboration and abstraction of the corresponding visual code (formality), thus combining pedagogical and socio-semiotic perspectives. The grid is applied to the analysis of 2819 visual images collected from school science textbooks and another 1630 visual images additionally collected from the press. The results show that the science textbooks in comparison to the press material: a) use ten times more images, b) use more images so as to familiarise their readers with the specialised techno-scientific content and codes, and c) tend to create a sense of higher empowerment for their readers by using the visual mode. Furthermore, as the educational level of the school science textbooks (i.e., from primary to lower secondary level) rises, the content specialisation projected by the visual images and the elaboration and abstraction of the corresponding visual code also increases. The above results have implications for the terms and conditions for the effective exploitation of visual material as the educational level rises as well as for the effective incorporation of visual images from press material into science classes.