Distributed execution of cognitive relaying with time incentive: multiple PU scenario

The prime focus of this study is in developing distributed algorithms for cognitive relaying with time incentive for multiple primary users (CRTI-M). CRTI-M is a symbiotic paradigm in which the incumbent primary users (PUs) of the spectrum, with weak transmission links, seek cooperation from the cognitive secondary user (SU) nodes in their vicinity, and in return reward them with an incentive time for the latter's own communication. When relaying through the SU network, each PU can either use its own spectrum or that of the other PUs. Cross-layer optimization problems are formulated to enable both these possibilities in a multi-hop multi-channel cognitive radio network with the objective of maximizing the cumulative time incentive for the SUs. Corresponding distributed algorithms are developed, which face the challenge of meeting the constraints of the formulated problems with only local information and the lack of a centralized controller. Further, to make the CRTI-M schemes practically realizable, a MAC scheduling protocol is suggested, which gives emphasis to the distributed implementation and provides a unified framework for the PUs and SUs. Simulation results are furnished to demonstrate the effectiveness of the proposed algorithms

Power allocation, bit loading and sub-carrier bandwidth sizing for OFDM-based cognitive radio

The function of the Radio Resource Management module of a Cognitive Radio (CR) system is to evaluate the available resources and assign them to meet the Quality of Service (QoS) objectives of the Secondary User (SU), within some constraints on factors which limit the performance of the Primary User (PU). While interference mitigation to the PU spectral band from the SU's transmission has received a lot of attention in recent literature; the novelty of our work is in considering a more realistic and effective approach of dividing the PU into sub-bands, and ensuring that the interference to each of them is below a specified threshold. With this objective, and within a power budget, we execute the tasks of power allocation, bit loading and sizing the sub-carrier bandwidth for an orthogonal frequency division multiplexing (OFDM)-based SU. After extensively analyzing the solution form of the optimization problems posed for the resource allocation, we suggest iterative algorithms to meet the aforementioned objectives. The algorithm for sub-carrier bandwidth sizing is novel, and not previously presented in literature. A multiple SU scenario is also considered, which entails assigning sub-carriers to the users, besides the resource allocation. Simulation results are provided, for both single and multi-user cases, which indicate the effectiveness of the proposed algorithms in a CR environment

The SS-SCR Scheme for dynamic spectrum access

We integrate the two models of Cognitive Radio (CR), namely, the conventional Sense-and-Scavenge (SS) Model and Symbiotic Cooperative Relaying (SCR). The resultant scheme, called SS-SCR, improves the efficiency of spectrum usage and reliability of the transmission links. SS-SCR is enabled by a suitable cross-layer optimization problem in a multihop multichannel CR network. Its performance is compared for different PU activity patterns with those schemes which consider SS and SCR separately and perform disjoint resource allocation. Simulation results depict the effectiveness of the proposed SS-SCR scheme. We also indicate the usefulness of cloud computing for a practical deployment of the scheme

Comparative Evaluation of Sealing Ability of Mineral Trioxide Aggregate and Biodentine Used for Root Furcation Perforation Repair – A Systematic Review"

Introduction: During endodontic operations, furcation perforations are a serious complication that might jeopardize periodontal health and the affected tooth\u27s long-term prognosis. To stop microbial leaking and encourage periodontal repair, these perforations must be properly sealed. Because of its sealing capabilities and biocompatibility, Mineral Trioxide Aggregate (MTA) has long been regarded as the gold standard for furcation healing. A more recent calcium silicate-based substance called biodentine has gained attention as a possible substitute because of its advantageous physical characteristics and bioactivity. Objectives: The aim of the present systematic review is to evaluate and compare the sealing ability of Mineral Trioxide Aggregate and Biodentine when used for the repair of root furcation perforations. Methods: A comprehensive electronic search was carried out across databases such as PubMed, Scopus, and Google Scholar. The included studies compared the sealing capabilities of MTA and Biodentine in the repair of furcation perforations by in vitro or ex vivo experimental investigations. Two reviewers independently carried out the data extraction and quality assessment in accordance with PRISMA criteria. Results:The majority of the included research evaluated the effectiveness of sealing using spectrophotometric, fluid filtration, dye penetration, or bacterial leakage techniques. Although MTA and Biodentine both showed adequate sealing capabilities, a number of studies found that Biodentine performed better or on par with MTA in terms of marginal adaption and decreased leakage. Conclusions: Root furcation holes can be successfully repaired using both mineral trioxide aggregate and biodentine. Although MTA is still often used, Biodentine seems to provide a similar sealing capacity combined with benefits like quicker setting time and better handling. To confirm these results and encourage evidence-based material selection in clinical practice, more standardized clinical and in vivo research is advised

Analyzing and Developing Technique for Mining Very Large Databases to Support Knowledge Exploration

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Diprosopus tetraophthalmos: a rare congenital anomaly

Diprosopus is an extremely rare form of conjoined twins which is found in newborns where there is partial or complete duplication of face. The etiology and pathophysiology remain unknown and no genetic mutations have definitively associated with the condition so far. This article described a case of an infant born at 33.4 weeks gestation with multiple congenital anomalies including diprosopus tetraophthalmos and discussed the possible hypothesis and implications of prenatal diagnosis

Vandetanib (ZD6474) in the Treatment of Medullary Thyroid Cancer

Vandetanib (ZD6474) is an orally bioavailable small molecule tyrosine kinase inhibitor of multiple growth factor receptors, including RET (Rearrange during transfection), vascular endothelial growth factor receptor-2 (VEGFR-2) and epidermal growth factor receptor (EGFR). The activity against RET and VEGF made it a good choice in the treatment of medullary thyroid cancer (MTC). As there is considerable cross talk between growth factor pathways, dual inhibition with such agents has become an attractive strategy, in the treatment of many malignancies with encouraging Phase II clinical trial data to date. Vandetanib was tested in two Phase II trials in the treatment of patients with medullary thyroid cancer at doses of 100 mg and 300 mg daily respectively. The encouraging results of these 2 trials led to a randomized phase II trial comparing this medication to placebo using a crossover design. More than 300 patients were included in this study, which ultimately showed a significant improvement in progression-free survival in patients taking vandetanib. Based on these results, the Oncology Drug Advisory Committee (ODAC) of the Food and Drug Administration (FDA) recommended that vandetanib be approved for the treatment of patients with unresectable locally advanced or metastatic medullary thyroid cancer

The Wide Fuel and its Characteristics

Water in diesel emulsion is an optional fuel, has a potential to reduce the formation of both nitrogen oxides, carbon dioxides and particulate matters in diesel engine. Thus the performance of this emulsified fuel strongly depends on the type of emulsion, stability of emulsion, amount of surfactant and the physio-chemical properties. In this study, water in diesel emulsion fuels of 5%, 10%, 20%, 25% water by volume was prepared by a mechanical stirrer. Physical and chemical properties of emulsion were examined as this properties could influence the spray characteristic of the emulsion which can affect the ignition delay and flame propagation, the carbon contents for emulsified fuel with 10% and 20% were low droplet size of the emulsion was found to be less than 2 µm. The water content in the emulsified fuel also include the amount of surfactant density and viscosity was found to be higher for all of the water in diesel emulsion the pure diesel

Specimen Design of Hydrogen Peroxide Systems for Attitude Control

Hydrogen peroxide (HP) is one of the most desirable alternatives to hydrazine and its derivatives, the most common type of fuel utilized in today’s rocket fuel industry. Research interest in HP as a rocket propellant has recently increased due to concerns over the carcinogenic nature of hydrazine-based fuels and the dinitrogen tetroxide rocket propellant combination. Hydrazine is a dangerously unstable, highly toxic, and carcinogenic substance, whereas HP is considered a green fuel. HP has a higher specific gravity and lower cost compared to its counterparts. HP cells are made with catalysts such as nickel, platinum, and palladium, and their efficiency is significantly higher than that of other cells. HP can be used as a monopropellant, bipropellant, or hybrid propellant in various compositions. The exothermic decomposition of HP yields water and oxygen. The rate of decomposition depends on factors such as temperature, concentration, pH, and the catalyst used. After treating the water with suitable salts, it can be consumed by astronauts, giving HP an advantage over other propellants