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.

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.

Novel monoclonal antibody recognition of oxidative DNA damage adduct, deoxycytidine-glyoxal

Glyoxal, a reactive aldehyde, is a decomposition product of lipid hydroperoxides, oxidative deoxyribose breakdown, or autoxidation of sugars, such as glucose. It readily forms DNA adducts, generating potential carcinogens such as glyoxalated deoxycytidine (gdC). A major drawback in assessing gdC formation in cellular DNA has been methodologic sensitivity. We have developed an mAb that specifically recognizes gdC. Balb/c mice were immunized with DNA, oxidatively modified by UVC/hydrogen peroxide in the presence of endogenous metal ions. Although UVC is not normally considered an oxidizing agent, a UVC/hydrogen peroxide combination may lead to glyoxalated bases arising from hydroxyl radical damage to deoxyribose. This damaging system was used to induce numerous oxidative lesions including glyoxal DNA modifications, from which resulted a number of clones. Clone F3/9/H2/G5 showed increased reactivity toward glyoxal-modified DNA greater than that of the immunizing antigen. ELISA unequivocally showed Ab recognition toward gdC, which was confirmed by gas chromatography-mass spectrometry of the derivatized adduct after formic acid hydrolysis to the modified base. Binding of Ab F3/9 with glyoxalated and untreated oligomers containing deoxycytidine, deoxyguanosine, thymidine, and deoxyadenosine assessed by ELISA produced significant recognition (p 0.0001) of glyoxal-modified deoxycytidine greater than that of untreated oligomer. Additionally, inhibition ELISA studies using the glyoxalated and native deoxycytidine oligomer showed increased recognition for gdC with more than a 5-fold difference in IC50 values. DNA modified with increasing levels of iron (II)/EDTA produced a dose-dependent increase in Ab F3/9 binding. This was reduced in the presence of catalase or aminoguanidine. We have validated the potential of gdC as a marker of oxidative DNA damage and showed negligible cross-reactivity with 8-oxo-2'-deoxyguanosine or malondialdehyde-modified DNA as well as its utility in immunocytochemistry. Formation of the gdC adduct may involve intermediate structures; however, our results strongly suggest Ab F3/9 has major specificity for the predominant product, 5-hydroxyacetyl-dC.

The authority of complexity

The assertion about the unique 'complexity' or the peculiarly intricate character of social phenomena has, at least within sociology, a long, venerable and virtually uncontested tradition. At the turn of the last century, classical social theorists, for example, Georg Simmel and Emile Durkheim, made prominent and repeated reference to this attribute of the subject matter of sociology and the degree to which it complicates, even inhibits the development and application of social scientific knowledge. Our paper explores the origins, the basis and the consequences of this assertion and asks in particular whether the classic complexity assertion still deserves to be invoked in analyses that ask about the production and the utilization of social scientific knowledge in modern society. We present John Maynard Keynes' economic theory and its practical applications as an illustration. We conclude that the practical value of social scientific knowledge is not dependent on a faithful, in the sense of complete, representation of social reality. Instead, social scientific knowledge that wants to optimize its practicality has to attend and attach itself to elements of social situations that can be altered or are actionable.

The unique complexity of social phenomena and the uses of social science knowledge

The assertion about the peculiarly intricate and complex character of social phenomena has, in much of social discourse, a virtually uncontested tradition. A significant part of the premise about the complexity of social phenomena is the conviction that it complicates, perhaps even inhibits the development and application of social scientific knowledge. Our paper explores the origins, the basis and the consequences of this assertion and asks in particular whether the classic complexity assertion still deserves to be invoked in analyses that ask about the production and the utilization of social scientific knowledge in modern society. We refer to one of the most prominent and politically influential social scientific theories, John Maynard Keynes' economic theory as an illustration. We conclude that, the practical value of social scientific knowledge is not necessarily dependent on a faithful, in the sense of complete, representation of (complex) social reality. Practical knowledge is context sensitive if not project bound. Social scientific knowledge that wants to optimize its practicality has to attend and attach itself to elements of practical social situations that can be altered or are actionable by relevant actors. This chapter represents an effort to re-examine the relation between social reality, social scientific knowledge and its practical application. There is a widely accepted view about the potential social utility of social scientific knowledge that invokes the peculiar complexity of social reality as an impediment to good theoretical comprehension and hence to its applicability.

Multiphase modelling of the characteristics of close coupled gas atomization

Not withstanding the high demand of metal powder for automotive and High Tech applications, there are still many unclear aspects of the production process. Only recentlyhas supercomputer performance made possible numerical investigation of such phenomena. This thesis focuses on the modelling aspects of primary and secondary atomization. Initially two-dimensional analysis is carried out to investigate the influence of flow parameters (reservoir pressure and gas temperature principally) and nozzle geometry on final powder yielding. Among the different types, close coupled atomizers have the best performance in terms of cost and narrow size distribution. An isentropic contoured nozzle is introduced to minimize the gas flow losses through shock cells: the results demonstrate that it outperformed the standard converging-diverging slit nozzle. Furthermore the utilization of hot gas gave a promising outcome: the powder size distribution is narrowed and the gas consumption reduced. In the second part of the thesis, the interaction of liquid metal and high speed gas near the feeding tube exit was studied. Both axisymmetric andnon-axisymmetric geometries were simulated using a 3D approach. The filming mechanism was detected only for very small metal flow rates (typically obtained in laboratory scale atomizers). When the melt flow increased, the liquid core overtook the adverse gas flow and entered in the high speed wake directly: in this case the disruption isdriven by sinusoidal surface waves. The process is characterized by fluctuating values of liquid volumes entering the domain that are monitored only as a time average rate: it is far from industrial robustness and capability concept. The non-axisymmetric geometry promoted the splitting of the initial stream into four cores, smaller in diameter and easier to atomize. Finally a new atomization design based on the lesson learned from previous cases simulation is presented.

Chemical synthesis of DNA and RNA containing thio-substituted bases and their post-synthetic modifications

Modified oligonucleotides containing sulphur group have been useful tools for studies of carcinogenesis, protein or nucleic acid structures and functions, protein-nucleic acid interactions, and for antisense modulation of gene expression. One successful example has been the synthesis and study of oligodeoxynucleotides containing 6-thio-2'-deoxyguanine. 6-Thio-2-deoxyguanosine was first discovered as metabolic compound of 6- mercaptopurine (6-MP). Later, it was applied as drug to cure leukaemia. During the research of its toxicity, a method was developed to use the sulphur group as a versatile position for post-synthetic modification. The advantage of application of post-synthetic modification lies in its convenience. Synthesis of oligomers with normal sequences has become routine work in most laboratories. However, design and synthesis of a proper phosphoramidite monomer for a new modified nucleoside are always difficult tasks even for a skilful chemist. Thus an alternative method (post-synthetic method) has been invented to overcome the difficulties. This was achieved by incorporation of versatile nucleotides into oligomers which contain a leaving group, that is sufficiently stable to withstand the conditions of synthesis but can be substituted by nucleophiles after synthesis, to produce, a series of oligomers each containing a different modified base. In the current project, a phosphoramidite monomer with 6-thioguanine has been successfully synthesised and incorporated into RNA. A deprotection procedure, which is specific for RNA was designed for oligomers containing 6-thioguanosine. The results were validated by various methods (UV, HPLC, enzymatic digestion). Pioneer work in utilization of the versatile sulphur group for post-synthetic modification was also tested. Post-synthetic modification was also carried out on DNA with 6- deoxythioguanosine. Electrophilic reagents with various functional groups (alphatic, aromatic, fluorescent) and bi-functional groups have been attached with the oligomers.

Visual performance of the human eye with soft hydrophilic contact lenses

The recording of visual acuity using the Snellen letter chart is only a limited measure of the visual performance of an eye wearing a refractive aid. Qualitative in addition to quantitative information is required to establish such a parameter: spatial, temporal and photometric aspects must all be incorporated into the test procedure. The literature relating to the correction of ametropia by refractive aids was reviewed. Selected aspects of a comparison between the correction provided by spectacles and contact lenses were considered. Special attention was directed to soft hydrophilic contact lenses. Despite technological advances which have produced physiologically acceptable soft lenses, there still remain associated with this recent form of refractive aid unpredictable visual factors. Several techniques for vision assessment were described, and previous studies of visual performance were discussed. To facilitate the investigation of visual performance in a clinical environment, a new semi-automated system was described: this utilized the presentation of broken ring test stimuli on a television screen. The research project comprised two stages. Initial work was concerned with the validation of the television system, including the optimization of its several operational variables. The second phase involved the utilization of the system in an investigation of visual performance aspects of the first month of regular daily soft contact lens wear by experimentally-naive subjects. On the basis of the results of this work an ‘homoeostatic’ model has been proposed to represent the strategy which an observer adopts in order to optimize his visual performance with soft contact lenses.

Studies on the anti-obesity activity of zinc-α2-glycoprotein in the rat

OBJECTIVE: To investigate the anti-obesity effect of the adipokine zinc-a(2)-glycoprotein (ZAG) in rats and the mechanism of this effect. SUBJECTS: Mature male Wistar rats (540 ± 83 g) were administered human recombinant ZAG (50 µg per 100 g body weight given intravenously daily) for 10 days, while control animals received an equal volume of phosphate-buffered saline (PBS). RESULTS: Animals treated with ZAG showed a progressive decrease in body weight, without a decrease in food and water intake, but with a 0.4 °C rise in body temperature. Body composition analysis showed loss of adipose tissue, but an increase in lean body mass. The loss of fat was due to an increase in lipolysis as shown by a 50% elevation of plasma glycerol, accompanied by increased utilization of non-esterified fatty acids, as evidenced by the 55% decrease in plasma levels. Plasma levels of glucose and triglycerides were also reduced by 36-37% and there was increased expression of the glucose transporter 4 in both skeletal muscle and adipose tissue. Expression of the lipolytic enzymes adipose triglyceride lipase and hormone-sensitive lipase in the white adipose tissue (WAT) were increased twofold after ZAG administration. There was almost a twofold increased expression of uncoupling proteins 1 and 3 in brown adipose tissue and WAT, which would contribute to increased substrate utilization. Administration of ZAG increased ZAG expression twofold in the gastrocnemius muscle, BAT and WAT, which was probably necessary for its biological effect. CONCLUSION: These results show that ZAG produces increased lipid mobilization and utilization in the rat.

Advances in predicting and manipulating the immunogenicity of biotherapeutics and vaccines

Therapeutic proteins are vital to the future of human health provision and the survival and profitability of the global pharmaceutical industry. Returns from protein therapeutics are experiencing unprecedented growth: both their number and their economic dividend have increased by an order of magnitude in the last 10 years. The potential immunogenicity of protein therapeutics raises many clinical and safety concerns. Many poorly understood factors relating to both product and host affect immune responses. Available laboratory measurement of immunogenicity is of little utility for predicting the clinical properties of biotherapeutics. Coupled with assay variability and standardization issues, this precludes adequate prediction of the biological or clinical responses of therapeutic proteins, arguing for the utilization of informatic strategies in the analysis and prediction of protein immunogenicity. Currently, many unresolved issues must be addressed and thus circumvented before effective prediction can become routine.

Professionals' awareness of operational antibiotic prescribing controls in UK NHS hospitals

In recent years, there have been increasing recommendations for multidisciplinary collaboration between clinical pharmacists and medical microbiologists in an attempt to control the quality (and quantity) of antibiotic prescribing. A questionnaire addressing the utilization of antibiotic prescribing controls was sent to the chief pharmacist and medical microbiologist in UK NHS hospitals. Responses were received from both the chief pharmacist and the medical microbiologist employed in the same hospital from 83 hospitals (a 30% response rate from two independent studies). A high level of disagreement and poor awareness was identified between the interprofessional staff groups regarding the existence of antibiotic formulary (with disagreement between the two groups, or not known by one or both respondents, in 46% of the paired hospitals, N=38) and guideline documents (13%, N=11), performance of antibiotic prescribing audits (40%, N=33), and whether pharmacists (52%, N=43) and medical microbiologists (77%, N=64) monitored physician compliance with antibiotic prescribing control documents. This study has identified poor knowledge of the existence of basic antibiotic prescribing control mechanisms and the role of professional colleagues. It is suggested that there is some way to go before 'Agenda for Change' principles of flexible and collaborative roles are met. © 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.

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.

Green-to-red tunable SHG of a quantum-dot laser in a PPKTP waveguide

Quasi-phase-matching is an important and widelyused technique in nonlinear optics enabling efficient frequency up-conversion. However, since its introduction almost half a century ago, this technique is well developed for near infrared (IR) but is intrinsically limited in spectral tunability in the visible range by the strict conditions set by the spatial modulation which compensates the momentum mismatch imposed by the dispersion. Here, we provide a fundamental generalization of quasi-phase-matching based on the utilization of a significant difference in the effective refractive indices of the high- and low-order modes in multimode waveguides. This concept enables to match the period of poling in a very broad wavelength range and opens up a new avenue for an order-ofmagnitude increase in wavelength range for frequency conversion from a single crystal. Using this approach, we demonstrate an all-room-temperature continuous-wave (CW) second harmonic generation (SHG) with over 60 nm tunability from green to red in a periodically-poled potassium titanyl phosphate (PPKTP) waveguide pumped by a single broadly-tunable quantumdot laser diode. © 2012 by Astro, Ltd.