Optimal partitioning method for stability analysis of continuous/discrete delay systems

This paper is concerned with the problem of stability analysis for continuous‐time/discrete‐time systems with interval time‐varying delay. Based on the idea of partitioning the delay interval into l nonuniform subintervals, new Lyapunov functionals are established. By utilizing the reciprocally convex approach to deal with the delay information in each subinterval, sufficient stability conditions are proposed in terms of linear matrix inequalities. Based on these criteria, the optimal partitioning method is given on the basis of the genetic algorithm. Finally, the reduced conservatism of the results in this paper is illustrated by numerical examples. Copyright © 2013 John Wiley & Sons, Ltd.     

Stabilization of discrete-time Markovian jump linear systems via time-delayed controllers

This paper is concerned with the stabilization problem for a class of discrete-time Markovian jump linear systems with time-delays both in the system state and in the mode signal. The delay in the system state may be time-varying. The delay in the mode signal is manifested as a constant mismatch of the modes between the controller and the system. We first show that the resulting closed-loop system is a time-varying delayed Markovian jump linear system with extended state space. Then a sufficient condition is proposed for the design of a controller such that the closed-loop system is stochastically stable. Finally, numerical simulation is used to illustrate the developed theory.     

A comparison of local variance,fractal dimension,and Moran's I as aids to multispectral image classification

The accuracy of traditional multispectral maximum‐likelihood image classification is limited by the multi‐modal statistical distributions of digital numbers from the complex, heterogenous mixture of land cover types in urban areas. This work examines the utility of local variance, fractal dimension and Moran's I index of spatial autocorrelation in segmenting multispectral satellite imagery with the goal of improving urban land cover classification accuracy. Tools available in the ERDAS Imagine^TM software package and the Image Characterization and Modeling System (ICAMS) were used to analyse Landsat ETM?+ imagery of Atlanta, Georgia. Images were created from the ETM?+ panchromatic band using the three texture indices. These texture images were added to the stack of multispectral bands and classified using a supervised, maximum likelihood technique. Although each texture band improved the classification accuracy over a multispectral only effort, the addition of fractal dimension measures is particularly effective at resolving land cover classes within urbanized areas, as compared to per‐pixel spectral classification techniques.     

Integral partitioning approach to robust stabilization for uncertain distributed time‐delay systems

In this paper, the problems of robust delay‐dependent stability analysis and stabilization are investigated for distributed delay systems with linear fractional uncertainties. By introducing an integral partitioning technique, a new form of Lyapunov functional is constructed and improved distributed delay‐dependent stability conditions are established in terms of linear matrix inequalities. Based on the criterion, a design algorithm for a state‐feedback controller is proposed. Following similar lines, we extend these results to uncertain distributed delay systems. The results developed in this paper can tolerate larger allowable delay than existing ones in the literature, which is illustrated by several examples. Copyright © 2011 John Wiley & Sons, Ltd.     

On the density profile within random and oriented wood-based composite panels: horizontal distribution

Wood composites are produced from the processing of discontinuous wood elements such as flakes and strands, with resin and other additives. Consolidation of the loose mat structure into a panel is achieved under heat and pressure, and the final product structure and properties are therefore governed not only by the properties of the wood elements but also by the forming and pressing processes. This paper deals with the density variation within the horizontal plane of flakeboards, in an approach that combines a structural model, based on the layout of the flakes, together with the consolidation model and mass transfer, both resulting from the hot-pressing process. The density distribution within the panels manufactured according to several possible combinations of random orientation and placement of flakes is analyzed, and the significant influence of the random character of the orientation of flakes during the forming process is highlighted.     

Metabolism of the antiandrogenic drug (Flutamide) by human CYP1A2

The antiandrogenic drug, flutamide, is widely used in the treatment of carcinoma of the prostate. The present study examines the metabolism of flutamide by human liver microsomes and purified recombinant human cytochrome P450s (CYP), expressed as fusion proteins. These studies show the principal role of CYP1A2 in the metabolism of flutamide to 2-hydroxyflutamide. A minor metabolite is formed during the metabolism of flutamide by CYP3A4 in the presence of an excess of added purified NADPH-P450 reductase. The metabolism of flutamide is inhibited by low concentrations of alpha-naphthoflavone and ketoconazole. Other substrates of CYP1A2, such as phenacetin, imipramine, caffeine, and estradiol, are also inhibitors of flutamide metabolism by CYP1A2. Of interest is the inhibition of flutamide metabolism by its metabolite, 2-hydroxyflutamide, and the inhibition of the 2- and 4- hydroxylation of estradiol by flutamide. CV1 cells do not metabolize flutamide to 2-hydroxyflutamide. In assays performed using this cell line transfected with the cDNA for the androgen receptor, flutamide is a pure antagonist, and 2-hydroxyflutamide, while a more potent androgen receptor (AR) antagonist, activates the AR at higher concentrations. Stable expression of CYPIA2 in these CV1 cells causes flutamide to exhibit agonistic properties at higher concentrations, a behavior not exhibited by cells stably transfected only with the expression vector encoding the AR. These findings raise the possibility that increased conversion of flutamide to 2-hydroxyflutamide or accumulation of 2-hydroxyflutamide in cells may contribute to the anomalous responses to flutamide that are observed in some advanced prostate cancers.     

Fatal acute pulmonary oedema after inhalation of fumes from polytetrafluoroethylene (PTFE)

The cases of three patients with acute pulmonary oedema caused by inhalation of fumes from heated polytetrafluoroethylene (PTFE) in a plastic factory are described. One patient died from profound hypoxaemia and shock shortly after admission, and the other two patients survived after medical treatment. This is the first report of fatal pulmonary oedema in a worker exposed to PTFE heated in a plastic extruding operation. From this observation, it appears that inhalation exposure to pyrolytic products from polytetrafluoroethylene can cause fatal respiratory complications. Special precautions are warranted in this kind of operation to prevent workers from being exposed to these substances.     

Thermo Sequenase DNA polymerase and T. acidophilum pyrophosphatase: new thermostable enzymes for DNA sequencing

A combination of thermostable enzymes has been developed that produces higher quality cycle sequences. Thermo Sequenase DNA polymerase is a thermostable enzyme engineered to catalyze the incorporation of ddNTPs with an efficiency several thousandfold better than other thermostable DNA polymerases. Since the enzyme also catalyzes pyrophosphorolysis at dideoxy termini, a thermostable inorganic pyrophosphatase is needed to remove the pyrophosphate produced during sequencing reactions. Thermoplasma acidophilum inorganic pyrophosphatase (TAP) is thermostable and effective for converting pyrophosphate to orthophosphate. The use of the combination of Thermo Sequenase polymerase and TAP for cycle sequencing yields sequence data with uniform band intensities, allowing the determination of longer, more accurate sequence reads. Uniform band intensities also facilitate interpretation of sequence anomalies and the presence of mixed templates. Sequencing PCR products of DNA amplified from heterozygous diploid individuals results in signals of equal intensity from each allele.     

Seroprevalence of human papillomavirus types 6 and 16 capsid antibodies in homosexual men

Human papillomavirus (HPV) has been implicated in the pathogenesis of anal carcinoma, which is increased in homosexual men. Little is known about the serologic response to HPV in normal or immunosuppressed men; therefore, HIV-infected and -uninfected homosexual men were screened for HPV-6 and -16 capsid antibodies. HIV-infected men had increased HPV DNA detection but did not significantly differ in the prevalence of serum HPV antibodies. HPV-6 DNA detection and the presence of anal warts were significantly correlated with serum antibody overall and in the HIV-infected subgroup. HPV-16 DNA detection was not significantly correlated with serum antibody overall or in either subgroup; however, HIV-infected men with high-grade anal squamous intraepithelial lesions were significantly more likely to have HPV-16 antibodies. HIV-infected men are able to generate an antibody response to HPV, and a lack of serum HPV antibodies cannot explain the increased HPV-associated disease seen in HIV-infected men.     

Caffeine-induced release of intracellular Ca2+ from Chinese hamster ovary cells expressing skeletal muscle ryanodine receptor. Effects on full-length and carboxyl-terminal portion of Ca2+ release channels

The ryanodine receptor (RyR)/Ca2+ release channel is an essential component of excitation-contraction coupling in striated muscle cells. To study the function and regulation of the Ca2+ release channel, we tested the effect of caffeine on the full-length and carboxyl-terminal portion of skeletal muscle RyR expressed in a Chinese hamster ovary (CHO) cell line. Caffeine induced openings of the full length RyR channels in a concentration-dependent manner, but it had no effect on the carboxyl-terminal RyR channels. CHO cells expressing the carboxyl-terminal RyR proteins displayed spontaneous changes of intracellular [Ca2+]. Unlike the native RyR channels in muscle cells, which display localized Ca2+ release events (i.e., "Ca2+ sparks" in cardiac muscle and "local release events" in skeletal muscle), CHO cells expressing the full length RyR proteins did not exhibit detectable spontaneous or caffeine-induced local Ca2+ release events. Our data suggest that the binding site for caffeine is likely to reside within the amino-terminal portion of RyR, and the localized Ca2+ release events observed in muscle cells may involve gating of a group of Ca2+ release channels and/or interaction of RyR with muscle-specific proteins.