On delayed genetic regulatory networks with polytopic uncertainties: Robust stability analysis

Copyright [2008] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.In this paper, we investigate the robust asymptotic stability problem of genetic regulatory networks with time-varying delays and polytopic parameter uncertainties. Both cases of differentiable and nondifferentiable time-delays are considered, and the convex polytopic description is utilized to characterize the genetic network model uncertainties. By using a Lyapunov functional approach and linear matrix inequality (LMI) techniques, the stability criteria for the uncertain delayed genetic networks are established in the form of LMIs, which can be readily verified by using standard numerical software. An important feature of the results reported here is that all the stability conditions are dependent on the upper and lower bounds of the delays, which is made possible by using up-to-date techniques for achieving delay dependence. Another feature of the results lies in that a novel Lyapunov functional dependent on the uncertain parameters is utilized, which renders the results to be potentially less conservative than those obtained via a fixed Lyapunov functional for the entire uncertainty domain. A genetic network example is employed to illustrate the applicability and usefulness of the developed theoretical results

Immunomodulation with Probiotics Against Aeromonas veronii in Grass Carp (Ctenopharyngodon idellus)

Aeromonas comprisea wide range of opportunistic bacteria that cause septicemia (blood poisoning)in fish.Withexpandingaquaculture, myriad methods have been used to combat these pathologiesincludingprobiotics and plant extracts which canpotentiallyaddress these diseases without harmingthe environment. Inthis study, four strains of opportunistic pathogens were isolated from diseased fish, thenmolecular identification of 16SrDNA was performed. Results identifiedthe four strains asAeromonas veronii, Shewanella sp., Bacillus cereus, and Aeromonas salmonicida. Experimental trialsrevealed that A.veroniiwas the primary strain. Multiple virulence-related factors were discovered, includingaerolysin (Aer), cytotoxic enterotoxin (Act), and the outer membrane protein (OmpAII).Thesewere foundonly in A.veronii. LC50 in grass carp was 3.6×104CFU/mLover 96 h, whereas the safe concentration was 9.11×103CFU/mL.Grass carp were challenged with 3 differentconcentrations of A.veronii. Following a 48h incubation period they were treated for 24 h, 48 h, and 72 h with 8.1×106CFU/mLconcentrations.The expression ofInterleukin-8(IL-8)andTumor Necrosis Factor-α(TNF-α)was up-regulated in the kidney, liver, spleen, and heart using qRT-PCR. Simultaneously, enzyme activity involving Pyruvate Kinase(PK),Alkaline Phosphatase(AKP), Alanine aminotransferase (ALT),Succinate Dehydrogenase (SDH), and Lysozyme (Lsz)inserum and liver tissues was significantly up-regulated.We found that probiotics enhancedgrowth of grass carp, improvedhealth status,and was beneficial in reducing the prevalence of this disease. Subsequent to feeding mixed probiotics,IL-8 and TNF-α geneexpression was significantly lower (p>0.05)than inthe infected group,at 16 and 31 days. Expression of these genes in the liver, spleen, and intestines of healthy grass carp fed probiotics wassignificantly up-regulated in contrast to grass carp fed a basal diet (p<0.05).Our results suggestthat use of probiotics as immune stimulator may improve the control of fish diseases in aquaculture

Broadband RCS Reduction of Microstrip Patch Antenna Using Bandstop Frequency Selective Surface

In this article, a simple and effective approach is presented to reduce the Radar Cross Section (RCS) of microstrip patch antenna in ultra broad frequency band. This approach substitutes a metallic ground plane of a conventional patch antenna with a hybrid ground consisting of bandstop Frequency Selective Surface (FSS) cells with partial metallic plane. To demonstrate the validity of the proposed approach, the influence of different ground planes on antenna’s performance is investigated. Thus, a patch antenna with miniaturized FSS cells is proposed. The results suggest that this antenna shows 3dB RCS reduction almost in the whole out-of operating band within 1-20GHz for wide incident angles when compared to conventional antenna, while its radiation characteristics are sustained simultaneously. The reasonable agreement between the measured and the simulated results verifies the efficiency of the proposed approach. Moreover, this approach doesn’t alter the lightweight, low-profile, easy conformal and easy manufacturing nature of the original antenna and can be extended to obtain low-RCS antennas with metallic planes in broadband that are quite suitable for the applications which are sensitive to the variation of frequencies