Selecting users in energy-efficient collaborative spectrum sensing

Cognitive radio network is defined as an intelligent wireless communication network that should be able to adaptively reconfigure its communication parameters to meet the demands of the transmission network or the user. In this context one possible way to utilize unused licensed spectrum without interfering with incumbent users is through spectrum sensing. Due to channel uncertainties, single cognitive (opportunistic) user cannot make a decision reliably and hence collaboration among multiple users is often required. Here collaboration among large number of users tends to increase power consumption and introduces large communication overheads. In this paper, the number of collaborating users is optimized in order to maximize the probability of detection for any given power budget in a cognitive radio network, while satisfying constraints on the false alarm probability. We show that for the maximum probability of detection, collaboration of only a subset of available opportunistic users is required. The robustness of our proposed spectrum sensing algorithm is also examined under flat Rayleigh fading and AWGN channel conditions.

Impact of the number of users on error probabilities in multiuser diversity systems

Multiuser diversity gain has been investigated well in terms of a system capacity formulation in the literature. In practice, however, designs on multiuser systems with nonzero error rates require a relationship between the error rates and the number of users within a cell. Considering a best-user scheduling, where the user with the best channel condition is scheduled to transmit per scheduling interval, our focus is on the uplink. We assume that each user communicates with the base station through a single-input multiple-output channel. We derive a closed-form expression for the average BER, and analyze how the average BER goes to zero asymptotically as the number of users increases for a given SNR. Note that the analysis of average BER even in SI SO multiuser diversity systems has not been done with respect to the number of users for a given SNR. Our analysis can be applied to multiuser diversity systems with any number of antennas.

Falls prevention and support:: translating research, integrating services and promoting the contribution of service users for quality and innovative programmes of care

Falls are a significant threat to the safety, health and independence of older citizens. Despite the substantial evidence that is available around effective falls prevention programmes and interventions, their translation into falls reduction programmes and policies has yet to be fully realised. While hip fracture rates are decreasing, the number and incidence of fall-related hospital admissions among older people continue to rise. Given the demographic trends that highlight increasing numbers of older people in the UK, which is broadly reflected internationally, there is a financial and social imperative to minimise the rate of falls and associated injuries. Falling is closely aligned to growing older (Slips, Trips and Falls Update: From Acute and Community Hospitals and Mental Health Units in England and Wales, Department of Health, HMSO, London, 2010). According to the World Health Organization, around 30% of older people aged over 65 and 50% of those over 80 will fall each year (Falls Fact Sheet Number 344, WHO, Geneva, 2010). Falls happen as a result of many reasons and can have harmful consequences, including loss of mobility and independence, confidence and in many cases even death (Cochrane Database Syst Rev 15, 2009, 146; Slips, Trips and Falls Update: From Acute and Community Hospitals and Mental Health Units in England and Wales, Department of Health, HMSO, London, 2010; Falling Standards, Broken Promises: Report of the National
Audit of Falls and Bone Health in Older People 2010, Health Care Quality
Improvement Partnership, London, 2011). What is neither fair nor correct is the
common belief by old and young alike that falls are just another inconvenience to put up with. The available evidence justifiably supports the view that well-organised services, based upon national standards and expert guidance, can prevent future falls among older people and reduce death and disability from fractures. This paper will draw from the UK, as an exemplar for policy and practice, to discuss the strategic direction of falls prevention programmes for older people and the partnerships that need to exist between researchers, service providers and users of services to translate evidence to the clinical setting. Second, it will propose some mechanisms for disseminating evidence to healthcare professionals and other stakeholders, to improve the quality and capacity of the clinical workforce.

Overconfidence, sexual health awareness and sexual health risk among young female users of sexual health clinics

This study explored the patterning of young people’s sexual health competence, and how this relates to sexual health outcomes. A survey of 381 young people attending two sexual health clinics in Northern Ireland was carried out between 2009 and 2010. Latent profile analysis of self-rated decision making, self-rated sexual health knowledge, and knowledge of sexually transmitted disease questionnaire scores was used to determine typologies of sexual health competence. Analysis revealed three categories of sexual health competence and explored their association with other behaviours and social characteristics. Young people’s subjective opinion of their sexual health competency, when not matched with a corresponding knowledge of sexual health, could place people at an increased risk of poor sexual health outcomes. Greater levels of peer pressure to have sex and early sexual debut were associated with poorer sexual health knowledge. This finding warrants further investigation, as the importance of self-perceived competence for sexual health screening and education programmes are considerable.

Health professionals' and service users' perspectives of shared care for monitoring wet age-related macular degeneration: a qualitative study alongside the ECHoES trial

Objectives: To explore the views of eye health professionals and service users on shared community and hospital care for wet or neovascular age-related macular degeneration (nAMD).

Method: Using maximum variation sampling, 5 focus groups and 10 interviews were conducted with 23 service users and 24 eye health professionals from across the UK (consisting of 8 optometrists, 6 ophthalmologists, 6 commissioners, 2 public health representatives and 2 clinical eye care advisors to local Clinical Commissioning Groups). Data were transcribed verbatim and analysed thematically using constant comparative techniques derived from grounded theory methodology.

Results: The needs and preferences of those with nAMD appear to be at odds with the current service being provided. There was enthusiasm among health professionals and service users about the possibility of shared care for nAMD as it was felt to have the potential to relieve hospital eye service burden and represent a more patient-centred option, but there were a number of perceived barriers to implementation. Some service users and ophthalmologists voiced concerns about optometrist competency and the potential for delays with referrals to secondary care if stable nAMD became active again. The health professionals were divided as to whether shared care was financially more efficient than the current model of care. Specialist training for optometrists, under the supervision of ophthalmologists, was deemed to be the most effective method of training and was perceived to have the potential to improve the communication and trust that shared care would require.

Conclusions: While shared care is perceived to represent a promising model of nAMD care, voiced concerns suggest that there would need to be greater collaboration between ophthalmology and optometry, in terms of interprofessional trust and communication.