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Bacterial foraging optimization (BFO) has attracted much attention and been widely applied in a variety of scientific and engineering applications since its inception. However, the fixed step size and a lack of information communication between bacterial individuals during the optimization process have significant impacts on the performance of BFO. To address these issues on real-parameter single objective optimization problems, this paper proposes a new bacterial foraging optimizer using new designed chemotaxis and conjugation strategies (BFO-CC). Via the new chemotaxis mechanism, each bacterium randomly selects a standard-basis-vector direction for swimming or tumbling; this approach may obviate calculating a random unit vector and could effectively get rid of interfering with each other between different dimensions. At the same time, the step size of each bacterium is adaptively adjusted based on the evolutionary generations and the information of the globally best individual, which readily makes the algorithm keep a better balance between a local search and global search. Moreover, the new designed conjugation operator is employed to exchange information between bacterial individuals; this feature can significantly improve convergence. The performance of the BFO-CC algorithm was comprehensively evaluated by comparing it with several other competitive algorithms (based on swarm intelligence) on both benchmark functions and real-world problems. Our experimental results demonstrated excellent performance of BFO-CC in terms of solution quality and computational efficiency. [ABSTRACT FROM AUTHOR]

We consider a family of rational maps T n, λ of λ -state diamond-like hierarchical Potts models concerning renormalization transformation. We give an asymptotic formula of the Hausdorff dimension of the Julia sets J ( T n, λ ) for sufficiently large λ . [ABSTRACT FROM AUTHOR]

To obtain a comprehensive picture of microtubule dynamics during conjugation, the mode of sexual reproduction in ciliates, we combined indirect immunofluorescence and three-dimensional imaging using confocal laser-scanning microscope to visualize the cellular localization of DNA, microtubules, and γ-tubulin, the main component of the microtubule-organizing center in mating Tetrahymena cells. As the conjugational stages proceeded, the distribution of γ-tubulin changed drastically and microtubules showed dynamic appearance and disappearance during meiosis, nuclear selection, nuclear exchange, and the development of new macronuclei. This study highlights the involvement of cytoskeletal regulation in the modulation of germline nuclear motilities required for ciliate reproduction. [ABSTRACT FROM AUTHOR]

The xanthones α-mangostin and γ-mangostin are the major bioactive compounds in Garcinia mangostana (mangosteen) fruit extracts. Previously, we reported the pharmacokinetic properties of a-mangostin in rats. The purpose of this follow-up study was to compare the pharmacokinetic characteristics of a-mangostin and γ-mangostin in rats if administered as either a pure compound or as a component of a mangosteen fruit extract. The absolute bioavailability of γ-mangostin when administered as a pure compound was determined by giving male Sprague Dawley rats 2mg/ kg γ-mangostin intravenously or 20mg/kg orally. A 160mg/kg aliquot of mangosteen fruit extract was administered, containing α-and γ-mangostin doses equal to 20mg/kg and 4.5mg/kg of each pure compound, respectively. Plasma samples were collected for both pharmacokinetic studies, and compound concentrations were measured by LC-MS/MS. The pharmacokinetic of γ-mangostin after intravenous administration followed a two-compartment body model. The half-life of the distribution phase was 2.40 min, and that of the elimination phase was 1.52 h. After oral administration, both α-and γ-mangostin underwent intensive first-pass metabolism, and both compounds were conjugated rapidly after oral administration. When given as an extract, the total absorption of α-and γ-mangostin was not increased, but the conjugation was slower, resulting in increased free (unconjugated) compound exposure when compared to pure compound administration. Since reported beneficial biological activities of mangosteen xanthones are based on the free, unconjugated compounds, food supplements containing mangosteen fruit extracts should be preferred over the administration of pure xanthones. [ABSTRACT FROM AUTHOR]

Abstract: Can a conjugative plasmid encoding enhanced biofilm forming abilities for its bacterial host facilitate the persistence of the plasmid in a bacterial population despite conferring diminished growth rate and segregative plasmid loss on its bearers? We construct a mathematical model in a chemostat and in a plug flow environment to answer this question. Explicit conditions for an affirmative answer are derived. Numerical simulations support the conclusion. [Copyright &y& Elsevier]

Cells aggregate and can be recovered from suspension when exposed to an ultrasonic standing wave field. The acoustic force on individual cells in a standing wave decreases with particle volume. A plane ultrasonic field generated by a transducer driven at 3.3 MHz was used here to investigate the removal of Escherischia coli, cells with dimensions of the order of 1.0 μm, from batch suspension by sedimentation over a range of concentrations (103 to 1010 cells ml−1). Cell removal efficiencies greater than 90% were achieved at initial concentrations of 1010 cells ml−1. Removal efficiencies decreased gradually to zero, as initial bacterial concentration was reduced to 107 cells ml−1. It was found that, when low concentrations of E. coli (103 to 105 cells ml−1) were added to suspensions of larger particles (i.e. yeast cells) that were of sufficient concentration to form aggregates in the sound field, E. coli could be harvested to an efficiency of 40%. The results imply that the E. coli became trapped and sediment with aggregates of larger particles. Some strains of bacteria are capable of DNA transfer by conjugation. The transfer rate of E. coli RP4 plasmid is order of magnitudes greater when conjugation occurs on solid medium rather than in liquid suspension. We have investigated whether the conjugation rate would also be higher in ultrasonically induced E. coli clumps than in free suspension. The donor strain was mixed with a recipient strain of E. coli, then sonicated in a capillary at 4.6 MHz in a tubular transducer for 5 min. The bacteria aggregated successfully. Results showed a three-fold increase in the rate of conjugation compared to a liquid mating control. [ABSTRACT FROM AUTHOR]

D.D.G.M. and A.L.Z each contributed to 50%. Due to the lack of suitable chromosomal markers, antibiotics could not be used to select transconjugant clones arising from matings between two Pseudomonas strains. As an alternative, a method based on the specificity of a lytic bacteriophage for the recipient strain was used successfully. © Rapid Science Ltd. 1998 [ABSTRACT FROM AUTHOR]

This theory proposes that electric conductivity, metallic or otherwise, ohmic or superconducting, is simply the result of electron density moving through atomic and molecular orbital overlaps in material bodies. The theory argues that electron density moves without resistance (is superconducting) while it is contained within extended quantum mechanical (QM) states which are constructed so that the electron wave function does not experience reflections at any interface. The theory states that ohmic conduction results when the electron wave function does experience reflections at QM interfaces, and requires the continuous external application of electromotive force (EMF) to overcome those reflections and maintain an electric current. [ABSTRACT FROM AUTHOR]

The article discusses the court case Russell v. Citigroup, Inc. in which the U.S. Sixth Circuit Court had held that the employee who has signed an arbitration agreement, need not require to arbitrate a claim that arose before the agreement was signed. In this case, court relied on the stated language and the context under which the agreement was signed. It mentions that the conjugation in the language was important in reaching to the decision.