Outage performance analysis and SWIPT optimization in energy-harvesting wireless sensor network deploying NOMA

Thanks to the benefits of non-orthogonal multiple access (NOMA) in wireless communications, we evaluate a wireless sensor network deploying NOMA (WSN-NOMA), where the destination can receive two data symbols in a whole transmission process with two time slots. In this work, two relaying protocols, so-called time-switching-based relaying WSN-NOMA (TSR WSN-NOMA) and power-splitting-based relaying WSN-NOMA (PSR WSN-NOMA) are deployed to study energy-harvesting (EH). Regarding the system performance analysis, we obtain the closed-form expressions for the exact and approximate outage probability (OP) in both protocols, and the delay-limited throughput is also evaluated. We then compare the two protocols theoretically, and two optimization problems are formulated to reduce the impact of OP and optimize the data rate. Our numerical and simulation results are provided to prove the theoretical and analytical analysis. Thanks to these results, a great performance gain can be achieved for both TSR WSN-NOMA and PSR WSN-NOMA if optimal values of TS and PS ratios are found. In addition, the optimized TSR WSN-NOMA outperforms that of PSR WSN-NOMA in terms of OP.Web of Science193art. no. 61

Outage and bit error probability analysis in energy harvesting wireless cooperative networks

This study focuses on a wireless powered cooperative communication network (WPCCN), which includes a hybrid access point (HAP), a source and a relay. The considered source and relay are installed without embedded energy supply (EES), thus are dependent on energy harvested from signals from the HAP to power their cooperative information transmission (IT). Taking inspiration from this, the author group investigates into a harvest-then-cooperate (HTC) protocol, whereas the source and the relay first harvest the energy from the AP in a downlink (DL) and then collaboratively work in uplink (UL) for IT of the source. For careful evaluation of the system performance, derivations of the approximate closed-form expression of the outage probability (OP) and an average bit error probability ( ABER) for the HTC protocol over Rayleigh fading channels are done. Lastly, the author group performs Monte-Carlo simulations to reassure the numerical results they obtained.Web of Science255746

Development of a Health Empowerment Programme to improve the health of working poor families: protocol for a prospective cohort study in Hong Kong

Introduction: People from working poor families are at high risk of poor health partly due to limited healthcare access. Health empowerment, a process by which people can gain greater control over the decisions affecting their lives and health through education and motivation, can be an effective way to enhance health, health-related quality of life (HRQOL), health awareness and health-seeking behaviours of these people. A new cohort study will be launched to explore the potential for a Health Empowerment Programme to enable these families by enhancing their health status and modifying their attitudes towards health-related issues. If proven effective, similar empowerment programme models could be tested and further disseminated in collaborations with healthcare providers and policymakers. Method and analysis: A prospective cohort study with 200 intervention families will be launched and followed up for 5 years. The following inclusion criteria will be used at the time of recruitment: (1) Having at least one working family member; (2) Having at least one child studying in grades 1–3; and (3) Having a monthly household income that is less than 75% of the median monthly household income of Hong Kong families. The Health Empowerment Programme that will be offered to intervention families will comprise four components: health assessment, health literacy, self-care enablement and health ambassador. Their health status, HRQOL, lifestyle and health service utilisation will be assessed and compared with 200 control families with matching characteristics but will not receive the health empowerment intervention. Ethics and dissemination: This project was approved by the University of Hong Kong—the Hospital Authority Hong Kong West Cluster IRB, Reference number: UW 12-517. The study findings will be disseminated through a series of peer-reviewed publications and conference presentations, as well as a yearly report to the philanthropic funding body–Kerry Group Kuok Foundation (Hong Kong) Limited.published_or_final_versio

GdxSi grown with mass-analyzed low energy dual ion beam epitaxy technique

Semiconducting gadolinium silicide GdxSi samples were prepared by mass-analyzed low-energy dual ion beam epitaxy technique. Auger electron spectroscopy depth profiles indicate that the gadolinium ions are implanted into the single-crystal silicon substrate and formed 20 nm thick GdxSi film. X-ray double-crystal diffraction measurement shows that there is no new phase formed. The XPS spectra show that one type of silicon peaks whose binding energy is between that of silicide and silicon dioxide, and the gadolinium peak of binding energy is between that of metal Gd and Gd2O3. All of these results indicate that an amorphous semiconductor is formed. (C) 2002 Elsevier Science B.V. All rights reserved

Trans-boundary air pollution in a Southeast Asian megacity: Case studies of the synoptic meteorological mechanisms and impacts on air quality

Local and regional sources contribute to degraded air quality in many urban areas, however, the influence of trans-boundary air pollution on surface PM2.5 is still poorly characterized in Southeast Asia (SEA) megacities. This study, for the first time, utilizes multi-platform datasets to elucidate two trans-boundary PM2.5 episodes in Ho Chi Minh City (HCMC), Vietnam, over the periods 25–29 Oct 2013 and 05–08 Oct 2015. Both events persisted with limited diurnal fluctuations and more than 60% of the Air Quality Index (AQI) values at an unhealthy level. PM2.5 concentrations during the events were 100% and 115% higher on average compared to local accumulation periods in the same months, highlighting the importance of trans-boundary pollution to local HCMC air quality. Backward trajectories, MERRA-2 AOD data, and CALIPSO images revealed the origin and synoptic meteorology conditions facilitating both trans-boundary pollution events. Anthropogenic PM2.5 emissions in continental East Asia fed the 2013 event, which was then transported by strong northeasterly winds triggered by an upper-level ridge near the Tibetan Plateau and a low-pressure system in western Pacific Ocean. In contrast, the 2015 event was the result of Indonesia biomass burning (BB), which was enhanced and transported by a westward propagating Western Pacific Subtropical High triggered by a strong El Nino ˜ event. Future climate change will likely increase the number of extreme El Nino ˜ events, leading to the increase of transboundary Indonesia BB events to HCMC. This study lays the groundwork for detailing the impact of trans-boundary pollution on local air quality in SEA megacities

Studies of the Decay B+- -> D_CP K+-

We report studies of the decay B+- -> D_CP K+-, where D_CP denotes neutral D mesons that decay to CP eigenstates. The analysis is based on a 29.1/fb data sample of collected at the \Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e+ e- storage ring. Ratios of branching fractions of Cabibbo-suppressed to Cabibbo-favored processes involving D_CP are determined to be B(B- -> D_1 K-)/B(B- -> D_1 pi-)=0.125 +- 0.036 +- 0.010 and B(B- -> D_2 K-)/B(B- -> D_2 pi-)=0.119 +- 0.028 +- 0.006, where indices 1 and 2 represent the CP=+1 and CP=-1 eigenstates of the D0 - anti D0 system, respectively. We also extract the partial rate asymmetries for B+- -> D_CP K+-, finding A_1 = 0.29 +- 0.26 +- 0.05 and A_2 = -0.22 +- 0.24 +- 0.04.Comment: 10 pages, 2 figures, submitted to Physical Review Letter

Knowledge about safe motherhood and HIV/AIDS among school pupils in a rural area in Tanzania

\ud The majority of adolescents in Africa experience pregnancy, childbirth and enter motherhood without adequate information about maternal health issues. Information about these issues could help them reduce their pregnancy related health risks. Existing studies have concentrated on adolescents' knowledge of other areas of reproductive health, but little is known about their awareness and knowledge of safe motherhood issues. We sought to bridge this gap by assessing the knowledge of school pupils regarding safe motherhood in Mtwara Region, Tanzania. We used qualitative and quantitative descriptive methods to assess school pupils' knowledge of safe motherhood and HIV/AIDS in pregnancy. An anonymous questionnaire was used to assess the knowledge of 135 pupils ranging in age from 9 to 17 years. The pupils were randomly selected from 3 primary schools. Underlying beliefs and attitudes were assessed through focus group interviews with 35 school children. Key informant interviews were conducted with six school teachers, two community leaders, and two health staffs. Knowledge about safe motherhood and other related aspects was generally low. While 67% of pupils could not mention the age at which a girl may be able to conceive, 80% reported it is safe for a girl to be married before she reaches 18 years. Strikingly, many school pupils believed that complications during pregnancy and childbirth are due to non-observance of traditions and taboos during pregnancy. Birth preparedness, important risk factors, danger signs, postpartum care and vertical transmission of HIV/AIDS and its prevention measures were almost unknown to the pupils. Poor knowledge of safe motherhood issues among school pupils in rural Tanzania is related to lack of effective and coordinated interventions to address reproductive health and motherhood. For long-term and sustained impact, school children must be provided with appropriate safe motherhood information as early as possible through innovative school-based interventions.\u

Population genetics of cancer cell clones: possible implications of cancer stem cells

Abstract Background The population dynamics of the various clones of cancer cells existing within a tumour is complex and still poorly understood. Cancer cell clones can be conceptualized as sympatric asexual species, and as such, the application of theoretical population genetics as it pertains to asexual species may provide additional insights. Results The number of generations of tumour cells within a cancer has been estimated at a minimum of 40, but high cancer cell mortality rates suggest that the number of cell generations may actually be in the hundreds. Such a large number of generations would easily allow natural selection to drive clonal evolution assuming that selective advantages of individual clones are within the range reported for free-living animal species. Tumour cell clonal evolution could also be driven by variation in the intrinsic rates of increase of different clones or by genetic drift. In every scenario examined, the presence of cancer stem cells would require lower selection pressure or less variation in intrinsic rates of increase. Conclusions The presence of cancer stem cells may result in more rapid clonal evolution. Specific predictions from theoretical population genetics may lead to a greater understanding of this process.</p