Interference-based optimal power-efficient access scheme for cognitive radio networks

In this paper, we propose a new optimization-based access strategy of multi-packet reception (MPR) channel for multiple secondary users (SUs) accessing the primary user (PU) spectrum. We devise an analytical model that realizes the multi-packet access strategy of the SUs. All the network receiving nodes have MPR capability. We aim at maximizing the throughput of the individual SUs subject to the PU's queue stability. Moreover, we are interested in providing an energy-efficient cognitive scheme. Therefore, we include energy constraints on the PU and SU average transmitted energy to the optimization problem. Each SU accesses the medium with certain probability that depends on the PU's activity, i.e., active or inactive. The numerical results show the advantage in terms of SU throughput of the proposed scheme over the conventional access scheme, where the SUs access the channel randomly with fixed power when the PU is sensed to be idle. 2015 IEEE.Qatar National Research FundScopu

Identification of Leishmania donovani as a cause of cutaneous leishmaniasis in Sudan

International audienceEight patients with cutaneous ulcers were referred to the Institute of Endemic Diseases, Khartoum, Sudan, from June 2000 to March 2002 for the diagnosis of suspected cutaneous leishmaniasis (CL). Diagnosis was confirmed parasitotogically by both positive Giemsa-stained smears and successful culture of Leishmania promastigotes in NNN medium. The eight parasite isolates were shown to belong to the Leishmania donovani complex by kDNA PCR. Isoenzyme typing of three isolates revealed that they were identical to the L. donovani MON-82 reference strain, and the gp63 PCR-RFLP profile showed similar patterns to a reference strain of MON-82. CL is endemic in most regions of Sudan and has been reported previously as being caused by L. major MON-74. The results of this study suggest that L. donovani is also a cause of CL in Sudan and that further study of isolates from Sudanese patients with cutaneous ulcers is warranted to ascertain whether L. donovani or L. major is the causative agent. (c) 2007 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved

Characterization of Wood-based Industrial Biorefinery Lignosulfonates and Supercritical Water Hydrolysis Lignin

Understanding the properties of any particular biorefinery or pulping residue lignin is crucial when choosing the right lignin for the right end use. In this paper, three different residual lignin types [supercritical water hydrolysis lignin (SCWH), ammonium lignosulfonate (A-LS), and sodium lignosulfonate (S-LS)] were evaluated for their chemical structure, thermal properties and water vapor adsorption behavior. SCWH lignin was found to have a high amount of phenolic hydroxyl groups and the highest amount of beta-O-4 linkages. Combined with a low ash content, it shows potential to be used for conversion into aromatic or platform chemicals. A-LS and S-LS had more aliphatic hydroxyl groups, aliphatic double bonds and C=O structures. All lignins had available C-3/C-5 positions, which can increase reactivity towards adhesive precursors. The glass transition temperature (T-g) data indicated that the SCWH and S-LS lignin types can be suitable for production of carbon fibers. Lignosulfonates exhibited considerable higher water vapor adsorption as compared to the SCWH lignin. In conclusion, this study demonstrated that the SCWH differed greatly from the lignosulfonates in purity, chemical structure, thermal stability and water sorption behavior. SCWH lignin showed great potential as raw material for aromatic compounds, carbon fibers, adhesives or polymers. Lignosulfonates are less suited for conversion into chemicals or carbon fibers, but due to the high amount of aliphatic hydroxyl groups, they can potentially be modified or used as adhesives, dispersants, or reinforcement material in polymers. For most value-adding applications, energy-intensive purification of the lignosulfonates would be required.Open access funding provided by Linnaeus University. Venla Hemmila and Stergios Adamopoulos would like to thank the Knowledge Foundation for the financial support (project titled "New environment-friendly board materials", 2015-2019). Arantxa Eceiza thanks the Basque Government (IT776-16) and SgiKer General Services of the University of the Basque Countr