Message-passing algorithms for optimal utilization of cognitive radio networks

Cognitive Radio has been proposed as a key technology to significantly improve spectrum usage in wireless networks by enabling unlicensed users to access unused resource. We present new algorithms that are needed for the implementation of opportunistic scheduling policies that maximize the throughput utilization of resources by secondary users, under maximum interference constraints imposed by existing primary users. Our approach is based on the Belief Propagation (BP) algorithm, which is advantageous due to its simplicity and potential for distributed implementation. We examine convergence properties and evaluate the performance of the proposed BP algorithms via simulations and demonstrate that the results compare favorably with a benchmark greedy strategy. © 2013 IEEE.

The role of resources in achieving target competitive positions

Competitive positioning has become an essential component of modern marketing management. For a firm to target effective positions for its products and services, it needs to decide on the market segment (where it will compete) as well as the differential advantage it will emphasise (how it will compete). Until recently, empirical research on positioning has received little attention, while substantial insight has been gained with respect to the concept of competitive positioning. Furthermore, Hooley, Moller and Broderick have highlighted the lack of empirical studies relative to theoretical ones related to positioning in general and to the relationship between positioning and the different components of each competitive positioning that a firm might choose. This study focuses on product competitive positioning in over-the-counter (OTC) pharmaceuticals in the British market. It was found that certain resources underpin specific competitive positions.

Knowledge-based development in leading regions across the globe:an exploratory analysis of the co-evolution of resources, capabilities, and outputs

It is widely observed that the global geography of innovation is rapidly evolving. This paper presents evidence concerning the contemporary evolution of the globe's most productive regions. The paper uncovers the underlying structure and co-evolution of knowledge-based resources, capabilities and outputs across these regions. The analysis identifies two key trends by which the economic evolution and growth patterns of these regions are differentiated-namely, knowledge-based growth and labour market growth. The knowledge-based growth factor represents the underlying commonality found between the growth of economic output, earnings and a range of knowledge-based resources. The labour market growth factor represents the capability of regions to draw on their human capital. Overall, spectacular knowledge-based growth of leading Chinese regions is evident, highlighting a continued shift of knowledge-based resources to Asia. It is concluded that regional growth in knowledge production investment and the capacity to draw on regional human capital reserves are neither necessarily traded-off nor complementary to each other. © 2012 Urban Studies Journal Limited.

Bilateral visual outcomes and service utilization of patients treated for 3 years with ranibizumab for neovascular age-related macular degeneration

Background: The aim of this study was to describe bilateral visual outcomes and the effect of incomplete follow-up after 3 years of ranibizumab therapy for neovascular age-related macular degeneration. Secondarily, the demands on service provision over a 3-year period were described. Methods: Data on visual acuity, hospital visits, and injections were collected over 36 months on consecutive patients commencing treatment over a 9-month period. Visual outcome was determined for 1) all patients, using last observation carried forward for missed visits due to early discontinuation and 2) only those patients completing full 36-month follow-up. Results: Over 3 years, 120 patients cumulatively attended hospital for 1,823 noninjection visits and 1,365 injection visits. A visual acuity loss of <15 letters (L) was experienced by 78.2% of patients. For all patients (n=120), there was a mean loss of 1.68 L using last observation carried forward for missing values. Excluding five patients who died and 30 who discontinued follow-up, mean gain was 1.47 L. In bilateral cases, final acuity was on average 9 L better in second eyes compared to first eyes. Also, 91% of better-seeing eyes continued to be the better-seeing eye. Conclusion: We have demonstrated our approach to describing the long-term service provision and visual outcomes of ranibizumab therapy for neovascular age-related macular degeneration in a consecutive cohort of patients. Although there was a heavy burden with very frequent injections and clinic visits, patients can expect a good level of visual stability and a very high chance of maintaining their better-seeing eye for up to 3 years. © 2014 Chavan et al. This work is published by Dove Medical Press Limited.

Transnationalism as a force for ethnic minority enterprise? The case of Somalis in Leicester

The extant literature on the phenomenon of transnational entrepreneurship has documented that in an era characterized by ‘superdiversity’, ethnic minorities use their diasporic networks to access an array of valuable resources in order to facilitate entrepreneurial activity. The article examines the connection between the notions of ‘superdiversity’, transnationalism and entrepreneurship by illuminating the dynamics of ‘transnational’ Somali business activity in Leicester. Considering this as a critical case, we attempt to address a gap in the literature on ethnic minority enterprise, which has struggled to address the ‘diversification of diversity’ that attends the arrival of new communities in the UK. Moreover, the article contributes to the discussion on the importance of ‘conditioning factors’ in explaining the ‘integration’ of new arrivals. Although familial and co-ethnic ties influence the availability and interaction of social, financial and human capital, this falls considerably short of neoliberal depictions of globalization. The political-economic context imposes harsh constraints upon Somali business activity which cannot be circumvented by the utilization of diasporic links, and transnational entrepreneurship is likely to be the preserve of a minority of minorities.