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In this paper, a relay-based energy-efficient cooperative communication strategy is proposed, under the hypothesis that the relay transmits with power drawn from energy-harvesting (EH) sources. Assuming a deterministic EH model under which the harvested amount of energy is known prior to transmission, a spectrally efficient adaptive Bit-Interleaved Coded (BIC) OFDM modulation scheme has been investigated. To guarantee the successful reception of a packet, Automatic Repeat Request (ARQ) protocol has been adopted. Assuming a long term static channel, the expected goodput (EGP) metric is used as cost function to be optimized. The most significant step-ahead of the proposed approach with respect to state-of-the-art is to increase the cooperation gain by using a bargaining game algorithm. Since most renewable sources are highly intermittent, they can induce significant fluctuation on the available power. The bargaining game algorithm takes into account the energy status of the relay and helps the source node to decide whether to cooperate or not with the relay. Achieved simulation results show that the bargaining game algorithm actually helps the nodes to select the right strategy, with a substantial goodput improvement, in particular when the energy availability of relay becomes intermittent due to the harvesting.

This paper proposes an adaptive Minimum Conditional Bit-ErrorRate (MCBER) Multi-User Detector (MUD) for a Space-Time Block Coded Multi-Carrier Code Division Multiple Access (STBC MC-CDMA) system that is based on Least-Mean-Square (LMS) optimization algorithm. Theoretical basics and simulation results have been presented and discussed for the proposed detector. Results shown in terms of BER evidenced that the MCBER detector outperforms the adaptive LMS-based implementation of MMSE MUD and also the ideal MMSE MUD exploiting the perfect knowledge of channel state-information. The moderate computational effort and the reduced sensitivity to parameterization seem to represent other relevant strengths of the proposed approach., Anglais

Purpose. To estimate the prevalence of self-reported sleep disorders (SD), to examine associations among demographic characteristics and familiar factors with SD, between SD and daytime sleep-related disorders (DD) and between evening habits and SD. Methods. An anonymous questionnaire was proposed to 1563 students (aged 14-21 years, mean age 16.5 ± 1.5; 42.8% males, 57.2% females) attending all classes of two high schools in Verona (North-East of Italy). Data were analyzed by some per- sonal and familial characteristics, by definition of three sleeper groups (non problem, occasional problem or problem-sleepers). Moreover SD were put in relation with DD and with some per- sonal evening attitudes. Results. The 75.5% of the subjects report at least one SD. Dif- ficulty falling asleep is the most frequent SD. The DD concern 91.2% of the sample. Females are more involved than males in SD and DD. All SD result strongly associated with the referred DD, except for sleepiness. Sport is significantly correlated with a minor prevalence of SD. Smoking and studying appear to be associated with SD. Conclusions. Since SD in youth constitute an important Public Health matter with a severe social impact they would be accu- rately studied to offer youth appropriate counselling given the importance of lifestyle in determining good sleep.

BACKGROUND: Doses of acetaminophen 40 mg kg(-1) rectally and 15 mg kg(-1) i.v. produce similar effect-site concentrations. However, the clinical effectiveness of these routes has not been compared. The aim of this study was to compare duration and efficacy of analgesia in children following adenotonsillectomy after acetaminophen either 40 mg kg(-1) rectally or 15 mg kg(-1) i.v. METHODS: Fifty children aged between 2 and 5 yr were recruited. They received a standardized anaesthetic, including 2 microg kg(-1) of fentanyl. Children were randomized to receive either rectal or i.v. acetaminophen. Postoperative pain was assessed regularly with the Children and Infants Postoperative Pain Scale score and rescue analgesia provided if scores were 4 or greater. The primary outcome measure was time to first analgesia. Results were plotted with a Kaplan-Meier analysis and median time to rescue analgesia compared between the groups. RESULTS: The protocol was successfully completed in 46 children. Forty-five children required rescue medication. The time to first rescue analgesia was longer in children receiving rectal acetaminophen (median 10 h, inter-quartile range 9-11 h) compared with those receiving i.v. acetaminophen (7, 6-10 h) with a P-value of 0.01 by log-rank test for equality in survivor function. Few children in either group required rescue analgesia within the first 6 h with differences between the groups being most prominent in the period from 6 to 10 h. CONCLUSIONS: Rectal acetaminophen 40 mg kg(-1) provides longer analgesia for moderately painful procedures when compared with 15 mg kg(-1) acetaminophen i.v.