A Characterization of Lyapunov Inequalities for Stability of Switched Systems

We study stability criteria for discrete-time switched systems and provide a meta-theorem that characterizes all Lyapunov theorems of a certain canonical type. For this purpose, we investigate the structure of sets of LMIs that provide a sufficient condition for stability. Various such conditions have been proposed in the literature in the past fifteen years. We prove in this note that a family of languagetheoretic conditions recently provided by the authors encapsulates all the possible LMI conditions, thus putting a conclusion to this research effort. As a corollary, we show that it is PSPACE-complete to recognize whether a particular set of LMIs implies stability of a switched system. Finally, we provide a geometric interpretation of these conditions, in terms of existence of an invariant set.Comment: arXiv admin note: text overlap with arXiv:1201.322

Joint Spectral Radius and Path-Complete Graph Lyapunov Functions

We introduce the framework of path-complete graph Lyapunov functions for approximation of the joint spectral radius. The approach is based on the analysis of the underlying switched system via inequalities imposed among multiple Lyapunov functions associated to a labeled directed graph. Inspired by concepts in automata theory and symbolic dynamics, we define a class of graphs called path-complete graphs, and show that any such graph gives rise to a method for proving stability of the switched system. This enables us to derive several asymptotically tight hierarchies of semidefinite programming relaxations that unify and generalize many existing techniques such as common quadratic, common sum of squares, and maximum/minimum-of-quadratics Lyapunov functions. We compare the quality of approximation obtained by certain classes of path-complete graphs including a family of dual graphs and all path-complete graphs with two nodes on an alphabet of two matrices. We provide approximation guarantees for several families of path-complete graphs, such as the De Bruijn graphs, establishing as a byproduct a constructive converse Lyapunov theorem for maximum/minimum-of-quadratics Lyapunov functions.Comment: To appear in SIAM Journal on Control and Optimization. Version 2 has gone through two major rounds of revision. In particular, a section on the performance of our algorithm on application-motivated problems has been added and a more comprehensive literature review is presente

The Effect of Garlic Extract on Expression of INFγ And Inos Genes in Macrophages Infected with Leishmania major

Background: The study was aimed to show the effect of molecular mechanism of Aqueous Garlic Extract (AGE) on expression of IFNγ and iNOS genes in Leishmania major.Methods: Leishmania major promastigotes (MRHO/IR/75/ER) were added to the in-vitro cultured J774 cell line, the cells were incubated for 72 hours. Various concentrations of garlic extract (9.25, 18.5, 37, 74, 148 mg/ml) were added to the infected cells. MTT assay was applied for cellular proliferation. After 72 hours of incubation, supernatants were collected and total RNA was extracted from the infected cells. The express of IFNγ and iNOS genes were studied by RT-PCR method.Results: The colorimetric MTT assay after 3 days of incubation showed cytotoxic effect of garlic extract with an IC50 of 37 mg/ml. In addition, IFNγ and iNOS genes expression by RT-PCR indicated that garlic extract lead to over expression of these genes in J774 cell line infected with L. major.Conclusion: Garlic extract exerts cytotoxic effect on infected J774 cell line. In addition, the hypothesis that garlic can improve cellular immunity with raising the expression of IFNγ and of iNOS genes con­firmed

Analysis of the Joint Spectral Radius Via Lyapunov Functions on Path-Complete Graphs

We study the problem of approximating the joint spectral radius (JSR) of a finite set of matrices. Our approach is based on the analysis of the underlying switched linear system via inequalities imposed between multiple Lyapunov functions associated to a labeled directed graph. Inspired by concepts in automata theory and symbolic dynamics, we define a class of graphs called path-complete graphs, and show that any such graph gives rise to a method for proving stability of the switched system. This enables us to derive several asymptotically tight hierarchies of semidefinite programming relaxations that unify and generalize many existing techniques such as common quadratic, common sum of squares, maximum/minimum-of-quadratics Lyapunov functions. We characterize all path-complete graphs consisting of two nodes on an alphabet of two matrices and compare their performance. For the general case of any set of n x n matrices we propose semidefinite programs of modest size that approximate the JSR within a multiplicative factor of 1/[superscript 4]√n of the true value. We establish a notion of duality among path-complete graphs and a constructive converse Lyapunov theorem for maximum/minimum-of-quadratics Lyapunov functions

When is a set of LMIs a sufficient condition for stability?

We study stability criteria for discrete time switching systems. We investigate the structure of sets of LMIs that are a sufficient condition for stability (i.e., such that any switching system which satisfies these LMIs is stable). We provide an exact characterization of these sets. As a corollary, we show that it is PSPACE-complete to recognize whether a particular set of LMIs implies the stability of a switching system

A retrospective study of hydatid cysts in patients undergoing liver and lung surgery in Tehran, Iran

Hydatid cyst, caused by larval stages of Echinococcus granulosus, is a zoonotic parasitic disease with public health importance. The disease is cosmopolitan and endemic in Iran. We conducted a retrospective study of the records of Milad Hospital, Tehran, Iran to establish the proportion of lung and liver surgical procedures that were performed for removal of hydatid cyst and to investigate the demography of the population undergoing lung and liver hydatid cyst surgery in this hospital. A retrospective cross-sectional study was conducted of records of 682 patients who underwent liver (n = 404) or lung (n = 278) surgery from April 2009 to March 2013. In 404 liver surgeries, 111 (27.5) diagnoses of hydatid cyst were verified. Liver hydatid infection demonstrated a significant age-related difference (p < 0.05). Cysts were found in 64 of 217 females (29.5) and 47 of 187 males (25.1). While in both sexes, more cysts were found in liver, the liver/lung ratio in females was significantly higher than in males (p < 0.001). Hydatid cyst was verified in 59 (21.2) of 278 lung surgeries: 27 of 105 females (25.7) and 32 of 173 males (18.5). There was a significant relationship between sex and organ site (p < 0.001) with the proportion of hydatid cysts in males occurring in lung higher than seen in females. In the five investigated years, approximately 25 of liver and lung surgeries conducted at Milad Hospital were related to hydatidosis. Increasing public awareness of principles of avoiding infection could reduce the risk of nearly a quarter of liver and lung surgeries and costs associated with the treatment of hydatid cysts. © 201

Picrotoxin Delineates Different Transport Configurations for Malate and gamma Aminobutyric Acid through TaALMT1

Plant-derived pharmacological agents have been used extensively to dissect the structure– function relationships of mammalian GABA receptors and ion channels. Picrotoxin is a noncompetitive antagonist of mammalian GABAA receptors. Here, we report that picrotoxin inhibits the anion (malate) efflux mediated by wheat (Triticum aestivum) ALMT1 but has no effect on GABA transport. The EC50 for inhibition was 0.14 nM and 0.18 nM when the ALMTs were expressed in tobacco BY2 cells and in Xenopus oocytes, respectively. Patch clamping of the oocyte plasma membrane expressing wheat ALMT1 showed that picrotoxin inhibited malate currents from both sides of the membrane. These results demonstrate that picrotoxin inhibits anion efflux effectively and can be used as a new inhibitor to study the ion fluxes mediated by ALMT proteins that allow either GABA or anion transport.Sunita A. Ramesh, Yu Long, Abolfazl Dashtbani-Roozbehani, Matthew Gilliham, Melissa H. Brown, and Stephen D. Tyerma

Dicentracin-Like from Asian sea bass Fish and Moronecidine-Like from Hippocampus Comes: Two Candidate Antimicrobial Peptides Against Leishmanina major Infection

Anti-Leishmanial drug therapy faces significant challenges related to cytotoxicity and drug resistance. Thus, new and efficient anti-Leishmanial drugs need to be identified. Due to their broad-spectrum antimicrobial and also immunomodulatory activities, antimicrobial peptides (AMPs) have attracted considerable attention. In this study, we comparatively assessed the anti-Leishmanial activities of two recently identified AMPs (dicentracin-like and moronecidine-like) and the well-known AMP piscidin from the hybrid striped bass. AMPs were first assessed against Leishmania major promastigotes using MTS. Subsequently, macrophages were infected with L. major and treated with AMPs to evaluate anti-amastigotes activity of AMPs, and non-infected macrophages were treated with AMPs to determine cytotoxicity against mammalian cells using MTS. The induction of factors limiting L. major growth (IL-12, TNF-α and reactive oxygen species (ROS)) by AMPs was measured by ELISA and dichlorofluorescin-diacetate (DCFH-DA) assay, respectively. Piscidin was more efficacious against L. major promastigotes as compared to dicentracine-like or moronocidin-like peptides, whereas, dicentracine-like and moronocidin-like peptide exhibited a higher activity against L. major amastigotes compared to piscidin. In turn, piscidin was most cytotoxic in non-infected macrophages compared to the other two AMPs. A direct association was observed between hydrophobicity of AMPs and their anti-promastigote and cytotoxic activities. Dicentracine-like or moronocidin-like peptides induced higher levels of IL-12, TNF-α and ROS in macrophages compared to piscidin. Collectively, our results suggest that dicentracine-like and moronocidin-like peptides represent potentially promising multi-functional therapeutic agents that might not only directly kill L. major but also induce anti-Leishmania factors that can limit L. major growth and intracellular survival

Prevalence of anti-toxoplasma gondii antibodies in young Iranians: The Caspian III study

Background: Toxoplasmosis is a worldwide neglected tropical and sub-tropical infection caused by Toxoplasma gondii (T. gondii). Most of the previous studies on the seroprevalence of T. gondii in Iran have been done at provincial level and on specific populations, including pregnant females. Socioeconomic parameters are associated with the prevalence of this disease. In this study, the authors evaluated the presence of anti-T. gondii antibodies and the related risk factors in Iranian adolescents. Methods: This was a cross-sectional study on serum samples from the third Iranian national school-based survey (the CASPIAN III study), which included 10- to 18-year-old students. Participants were selected by multistage sampling from 27 Iranian provinces. In this study, serum samples of 882 adolescents from 16 provinces were randomly selected and examined for IgG and IgM antibodies against T. gondiiby theEnzymeLinked Fluorescent Assay (ELFA).Demographicandsocioeconomic factors related to T. gondii infection were gathered using the global school-based health survey (GSHS) questionnaire. Results: The overall T. gondii IgGandIgMseropositivitywas56.3 (95 CI: 53.4 to 59.2)and3.7 (95CI: 2.7 to 4.9), respectively. In multivariate logistic regression model, family size was statistically associated with seroprevalence of anti T. gondii IgG. Living in crowded households (households with more than 4 people vs. households with less than 4 people) increased the risk of seropositivity of T. gondii (OR: 1.40, 95 CI: 1.10 to 1.99). Conclusions: The results of this study indicate that about 40 of Iranian adolescents have not had contact with the T. gondii, thus the risk of congenital toxoplasmosis might be high in young females. Also, household size was the main factor associated with T. gondii infection. Preventive strategies and health education in Iranian adolescents are recommended. © 2017, Pediartric Infections Research Center