José Carlos Ribeiro

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The new IEEE 802.21 standard specifies link layer intelligence and other related network information to upper layers in order to optimize handovers between networks of different types, such as WiMAX, Wi-Fi, and 3GPP. This paper makes a short description of 802.21 standard, how it is implemented in ns-2, and the signaling used in a handover between WiMAX and(More)
The aims of this study were: (1) to observe participation in moderate-to-vigorous physical activity (MVPA) during school recess periods; (2) to determine the relative importance of physical activity during recesses to overall daily physical activity; and (3) to examine differences in physical activity between the sexes during unstructured recess periods.(More)
— This paper presents a characterization of spectrum opportunities in GSM900 downlink bands, for fixed and mobile scenarios. A testbed to analyze coexistence between the licensed GSM900 downlink system and an OFDM based secondary system that opportunistically shares the same spectrum is presented. Coexistence analysis is based on metrics such as spectrum(More)
BACKGROUND Active commuting to/from school is an important source of physical activity that has been declining over the past years. Although it is an affordable and simple way of increasing physical activity levels it is still unclear whether it has enough potential to improve health. Therefore, the aim of this cross sectional study was to examine the(More)
The purpose of this study was to analyse the associations between sports participation, levels of moderate to vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF). The study comprised 310 participants (183 girls and 127 boys) aged 11-18 years. Sports participation was assessed by questionnaire and habitual physical activity (PA) was(More)
This paper proposes some reflections concerning the process of creation of multiple virtual identities usually verified in several online social platforms of informal interaction based on textual/synchronous modality. With this intention, it discusses characterization, exploratory possibilities (personal and social-communicative) and reasons which lead(More)
The aim of this study was to examine any differences in cardiovascular disease (CVD) risk in Portuguese children split by parental educational level. A cross-sectional school-based study was conducted in 2011 on 359 Portuguese children (202 girls and 157 boys) aged 10 to 17 years (mean age ± SD = 13.9 ± 1.98 years). Height and body mass were assessed to(More)
Although the 6-minute walk test (6MWT) has been widely used in patients with schizophrenia, there is a lack of scientific evidence about its reliability and validity in this population. The first goal of this study was to explore the test-retest reliability of the 6MWT and to identify the associated parameters that contribute to the variability of the(More)