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Sample records for arcab two-component system

  1. A TWO-COMPONENT PRODUCTION INVENTORY-ASSEMBLY SYSTEM

    Directory of Open Access Journals (Sweden)

    V.S.S. Yadavalli

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: The paper considers a two-component continuous review inventory system where one of two components is produced by the organisation and the other is supplied by an outside supplier. The two components are assembled into an end product. There are two different product types. Demand occurs according to a Poisson process for each of the product types. It is assumed that product 1 is produced and its production time is arbitrarily distributed. Production is interrupted when the inventory level of product 1 reaches its maximum level. Replenishment of product 2 is done according to an adjustable reorder policy, and the lead-time follows an exponential distribution. Identifying the stochastic process as a semi-regenerative process, steady-state measures such as mean stationary rate of the number of demands lost, mean number of demands satisfied, mean number of replenishments made, are found. The total unutilised capacity of the production system is found, and a cost analysis is also studied. A numerical example is provided to illustrate the results obtained.

    AFRIKAANSE OPSOMMING: ‘n Voorraadsisteem wat kontinu hersien word vir twee verskillende komponenttipes word bestudeer. Die komponente word gebruik vir twee verskillende produktipes. Die verbruik van elke produktipe word beskryf deur ‘n Poissonverdeling. Die produksietyd vir produktipe 1 is arbitrêr verdeel. Sodra die voorraadpeil van produk 1 die maksimum bereik, word produksie gestaak. Aanvulling van produktipe 2 word gedoen volgens ‘n verstelbare herbestelbeleid met eksponensiele leityd. Identifisering van die stogastiese proses as half-regenererend lei vervolgens tot bepaling van gestadigde maatstawe soos gemiddelde aantal verlore eenhede, gemiddelde bevredigde vraag, en gemiddelde aantal aanvullings. Die totale ledigheid van die sisteem word bepaal en die gepaardgaande koste bereken. ‘n Syfervoorbeeld word voorgehou om die resultate te bevestig.

  2. Theory of Ostwald ripening in a two-component system

    Science.gov (United States)

    Baird, J. K.; Lee, L. K.; Frazier, D. O.; Naumann, R. J.

    1986-01-01

    When a two-component system is cooled below the minimum temperature for its stability, it separates into two or more immiscible phases. The initial nucleation produces grains (if solid) or droplets (if liquid) of one of the phases dispersed in the other. The dynamics by which these nuclei proceed toward equilibrium is called Ostwald ripening. The dynamics of growth of the droplets depends upon the following factors: (1) The solubility of the droplet depends upon its radius and the interfacial energy between it and the surrounding (continuous) phase. There is a critical radius determined by the supersaturation in the continuous phase. Droplets with radii smaller than critical dissolve, while droplets with radii larger grow. (2) The droplets concentrate one component and reject the other. The rate at which this occurs is assumed to be determined by the interdiffusion of the two components in the continuous phase. (3) The Ostwald ripening is constrained by conservation of mass; e.g., the amount of materials in the droplet phase plus the remaining supersaturation in the continuous phase must equal the supersaturation available at the start. (4) There is a distribution of droplet sizes associated with a mean droplet radius, which grows continuously with time. This distribution function satisfies a continuity equation, which is solved asymptotically by a similarity transformation method.

  3. Efficient two-component relativistic method for large systems

    International Nuclear Information System (INIS)

    This paper reviews a series of theoretical studies to develop efficient two-component (2c) relativistic method for large systems by the author’s group. The basic theory is the infinite-order Douglas-Kroll-Hess (IODKH) method for many-electron Dirac-Coulomb Hamiltonian. The local unitary transformation (LUT) scheme can effectively produce the 2c relativistic Hamiltonian, and the divide-and-conquer (DC) method can achieve linear-scaling of Hartree-Fock and electron correlation methods. The frozen core potential (FCP) theoretically connects model potential calculations with the all-electron ones. The accompanying coordinate expansion with a transfer recurrence relation (ACE-TRR) scheme accelerates the computations of electron repulsion integrals with high angular momenta and long contractions

  4. Mitochondrial two-component signaling systems in Candida albicans.

    Science.gov (United States)

    Mavrianos, John; Berkow, Elizabeth L; Desai, Chirayu; Pandey, Alok; Batish, Mona; Rabadi, Marissa J; Barker, Katherine S; Pain, Debkumar; Rogers, P David; Eugenin, Eliseo A; Chauhan, Neeraj

    2013-06-01

    Two-component signal transduction pathways are one of the primary means by which microorganisms respond to environmental signals. These signaling cascades originated in prokaryotes and were inherited by eukaryotes via endosymbiotic lateral gene transfer from ancestral cyanobacteria. We report here that the nuclear genome of the pathogenic fungus Candida albicans contains elements of a two-component signaling pathway that seem to be targeted to the mitochondria. The C. albicans two-component response regulator protein Srr1 (stress response regulator 1) contains a mitochondrial targeting sequence at the N terminus, and fluorescence microscopy reveals mitochondrial localization of green fluorescent protein-tagged Srr1. Moreover, phylogenetic analysis indicates that C. albicans Srr1 is more closely related to histidine kinases and response regulators found in marine bacteria than are other two-component proteins present in the fungi. These data suggest conservation of this protein during the evolutionary transition from endosymbiont to a subcellular organelle. We used microarray analysis to determine whether the phenotypes observed with a srr1Δ/Δ mutant could be correlated with gene transcriptional changes. The expression of mitochondrial genes was altered in the srr1Δ/Δ null mutant in comparison to their expression in the wild type. Furthermore, apoptosis increased significantly in the srr1Δ/Δ mutant strain compared to the level of apoptosis in the wild type, suggesting the activation of a mitochondrion-dependent apoptotic cell death pathway in the srr1Δ/Δ mutant. Collectively, this study shows for the first time that a lower eukaryote like C. albicans possesses a two-component response regulator protein that has survived in mitochondria and regulates a subset of genes whose functions are associated with the oxidative stress response and programmed cell death (apoptosis). PMID:23584995

  5. Brazilian two-component TLD albedo neutron individual monitoring system

    International Nuclear Information System (INIS)

    Since 1983, Instituto de Radioprotecao e Dosimetria, Brazil, uses a TLD one-component albedo neutron monitor, which has a single different calibration factor specifically for each installation type. In order to improve its energy response, a two-component albedo monitor was developed, which measure the thermal neutron component besides the albedo one. The two-component monitor has been calibrated in reference neutron fields: thermal, five accelerator-produced monoenergetic beams (70, 144, 565, 1200 and 5000 keV) and five radionuclide sources (252Cf, 252Cf(D2O), 241Am-Be, 241Am-B and 238Pu-Be) at several distances. Since January 2008, mainly Brazilian workers who handle neutron sources at different distances and moderation, such as in well logging and calibration facilities are using it routinely.

  6. The Fractional Virial Potential Energy in Two-Component Systems

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    Caimmi, R.

    2008-12-01

    Full Text Available Two-component systems are conceived as macrogases, and the related equation of state is expressed using the virial theorem for subsystems, under the restriction of homeoidally striated density profiles. Explicit calculations are performed for a useful reference case and a few cases of astrophysical interest, both with and without truncation radius. Shallower density profiles are found to yield an equation of state, $phi=phi(y,m$, characterized (for assigned values of the fractional mass, $m=M_j/ M_i$ by the occurrence of two extremum points, a minimum and a maximum, as found in an earlier attempt. Steeper density profiles produce a similar equation of state, which implies that a special value of $m$ is related to a critical curve where the above mentioned extremum points reduce to a single horizontal inflexion point, and curves below the critical one show no extremum points. The similarity of the isofractional mass curves to van der Waals' isothermal curves, suggests the possibility of a phase transition in a bell-shaped region of the $({sf O}yphi$ plane, where the fractional truncation radius along a selected direction is $y=R_j/R_i$, and the fractional virial potential energy is $phi=(E_{ji}_mathrm{vir}/(E_{ij}_mathrm{vir}$. Further investigation is devoted to mass distributions described by Hernquist (1990 density profiles, for which an additional relation can be used to represent a sample of $N=16$ elliptical galaxies (EGs on the $({sf O}yphi$ plane. Even if the evolution of elliptical galaxies and their hosting dark matter (DM haloes, in the light of the model, has been characterized by equal fractional mass, $m$, and equal scaled truncation radius, or concentration, $Xi_u=R_u/r_u^dagger$, $u=i,j$, still it cannot be considered as strictly homologous, due to different values of fractional truncation radii, $y$, or fractional scaling radii, $y^dagger=r_j^dagger/r_i^dagger$, deduced from sample objects.

  7. Crystallographic characterization of a multidomain histidine protein kinase from an essential two-component regulatory system

    OpenAIRE

    Zhao, Haiyan; Tang, Liang

    2009-01-01

    The multidomain cytoplasmic portion of the histidine protein kinase from an essential two-component signal transduction system has been crystallized and X-ray data have been collected to 2.8 Å resolution.

  8. Cauchy problem for a generalized weakly dissipative periodic two-component Camassa-Holm system

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    Wenxia Chen

    2014-05-01

    Full Text Available In this article, we study a generalized weakly dissipative periodic two-component Camassa-Holm system. We show that this system can exhibit the wave-breaking phenomenon and determine the exact blow-up rate of strong solution to the system. In addition, we establish a sufficient condition for having a global solution.

  9. Global dissipative solutions for the two-component Camassa-Holm shallow water system

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    Yujuan Wang

    2015-01-01

    Full Text Available This article presents a continuous semigroup of globally defined weak dissipative solutions for the two-component Camassa-Holm system. Such solutions are established by using a new approach based on characteristics a set of new variables overcoming the difficulties inherent in multi-component systems.

  10. The Qualitative Analysis of a Solution of a Series Maintenance System with Two Components

    Institute of Scientific and Technical Information of China (English)

    GUOWei-hua; YANGMing-zeng

    2003-01-01

    In this paper, firstly we study the series maintenance system with two components, obtain its exsistence and uniqueness of a dynamic state nonnegative solution by strongly continuous semigroups of operators theory. Then we prove that 0 is the eigenvalue of the system's host operators, and finally we study the eigenvector of the eigenvalue 0.

  11. The essential YycFG two-component system controls cell wall metabolism in Bacillus subtilis

    DEFF Research Database (Denmark)

    Bisicchia, Paola; Noone, David; Lioliou, Efthimia;

    2007-01-01

    Adaptation of bacteria to the prevailing environmental and nutritional conditions is often mediated by two-component signal transduction systems (TCS). The Bacillus subtilis YycFG TCS has attracted special attention as it is essential for viability and its regulon is poorly defined. Here we show...

  12. A novel two-component system found in Mycobacterium tuberculosis

    DEFF Research Database (Denmark)

    Morth, J. P.; Gosmann, S.; Nowak, E.;

    2005-01-01

    We report the identification of a novel two-component system in Mycobacterium tuberculosis. We show that the putative histidine kinase with the genomic locus tag Rv3220c is able to self-phosphorylate in the presence of Mg2+/ATP and subsequently transfer the phosphoryl group to a novel response...

  13. Predicting Inter-Species Cross-Talk in Two-Component Signalling Systems

    OpenAIRE

    S. Pawelczyk; Scott, KA; Hamer, R.; Blades, G; Deane, CM; Wadhams, GH

    2012-01-01

    Phosphosignalling pathways are an attractive option for the synthetic biologist looking for a wide repertoire of modular components from which to build. We demonstrate that two-component systems can be used in synthetic biology. However, their potential is limited by the fact that host cells contain many of their own phosphosignalling pathways and these may interact with, and cross-talk to, the introduced synthetic components. In this paper we also demonstrate a simple bioinformatic tool that...

  14. Comparative Genomic Analysis of Two-Component Signal Transduction Systems in Probiotic Lactobacillus casei

    OpenAIRE

    Yu, Shuijing; Peng, Yanping; Chen, Wanyi; Deng, Yangwu; Guo, Yanhua

    2014-01-01

    Lactobacillus casei has traditionally been recognized as a probiotic, thus needing to survive the industrial production processes and transit through the gastrointestinal tract before providing benefit to human health. The two-component signal transduction system (TCS) plays important roles in sensing and reacting to environmental changes, which consists of a histidine kinase (HK) and a response regulator (RR). In this study we identified HKs and RRs of six sequenced L. casei strains. Ortholo...

  15. Topological aspects in a two-component Bose condensed system in a neutron star

    International Nuclear Information System (INIS)

    By making use of Duan–Ge's decomposition theory of gauge potential and the topological current theory proposed by Prof. Duan Yi–Shi, we study a two-component superfluid Bose condensed system, which is supposed to be realized in the interior of neutron stars in the form of the coexistence of a neutron superfluid and a protonic superconductor. We propose that this system possesses vortex lines. The topological charges of the vortex lines are characterized by the Hopf indices and the Brower degrees of ø-mapping. (the physics of elementary particles and fields)

  16. The Two-Component Virial Theorem and the Physical Properties of Stellar Systems.

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    Dantas; Ribeiro; Capelato; de Carvalho RR

    2000-01-01

    Motivated by present indirect evidence that galaxies are surrounded by dark matter halos, we investigate whether their physical properties can be described by a formulation of the virial theorem that explicitly takes into account the gravitational potential term representing the interaction of the dark halo with the baryonic or luminous component. Our analysis shows that the application of such a "two-component virial theorem" not only accounts for the scaling relations displayed by, in particular, elliptical galaxies, but also for the observed properties of all virialized stellar systems, ranging from globular clusters to galaxy clusters. PMID:10587482

  17. Collective degrees of freedom of the two-component nuclear system

    International Nuclear Information System (INIS)

    A microscopic proton-neutron symplectic model of collective motions, based on the non-compact symplectic group Sp(12, R), is introduced by considering the symplectic geometry of the two-component many-particle nuclear system. The dynamical group of the whole many-particle system allows the separation of the nuclear variables into kinematical (internal) and dynamical (collective) ones. Then, the number and type of collective degrees of freedom, related to the dynamical variables, are determined properly by the group-theoretical consideration of the coordinate transformation of the microscopic configuration space, spanned by the m = A-1 translationally invariant Jacobi vectors, to the collective and intrinsic submanifolds. As a result the nuclear wave functions are represented as a product of collective and intrinsic parts. Dynamical content of the Sp(12,R) model is revealed by considering its GCM(6) submodel, which appears as an irrotational flow collective model of the two-component nuclear system augmented by the SO(6) intrinsic vortex degrees of freedom. Consequently, the Sp(12,R) model appears therefore as a hydrodynamic collective model of the proton-neutron nuclear system which include 21 collective irrotational flow degrees of freedom and an U(6) intrinsic structure associated with the vortex degrees of freedom. The latter play an important role in the construction of the microscopic wave functions because they allow to ensure the full antisymmetry of the total wave function and are responsible for the appearance of the low-lying collective bands. (orig.)

  18. Crystallographic characterization of a multidomain histidine protein kinase from an essential two-component regulatory system

    International Nuclear Information System (INIS)

    The multidomain cytoplasmic portion of the histidine protein kinase from an essential two-component signal transduction system has been crystallized and X-ray data have been collected to 2.8 Å resolution. YycGF is a highly conserved two-component signal transduction system that is specific to low-G+C Gram-positive bacteria, including many important human pathogens. It has been recognized as a crucial regulatory system for cell-wall metabolism. YycG, the histidine protein kinase of this system, is a multidomain transmembrane protein. The truncated cytoplasmic portion of YycG from Bacillus subtilis encompassing the PAS domain, the dimerization domain and the catalytic domain was expressed, purified and crystallized. X-ray data were collected to 2.8 Å resolution with a completeness of 98.2% and an overall Rmerge of 5.6%. The crystals belonged to space group P61 or P65, with unit-cell parameters a = 135.0, c = 133.0 Å. The selenomethionine-substituted version of the protein was crystallized and X-ray data were collected to 3.6 Å resolution for subsequent MAD phasing

  19. Coexistence of superfluid and metallic-like state in two-component fermionic systems

    Energy Technology Data Exchange (ETDEWEB)

    Continentino, M.A., E-mail: mucio@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Padilha, Igor T. [Universidade Federal do Amazonas, Departamento de Física, Av. Gal. Rodrigo Octávio Jordão Ramos, 3000 Setor Sul e Norte, Coroado I, Manaus (Brazil)

    2012-01-09

    We study the possibility of coexistence in a two component fermionic system of a superfluid state with a metallic-like state with gapless excitations at a Fermi surface. We consider a two-component system with mixing (hybridization) between them and attractive interactions between only one type of quasi-particles. Besides a conventional BCS regime, we find for sufficiently strong interactions a superfluid state of Bose condensed pairs at zero temperature. We investigate whether these pairs can coexist with a metallic-like state characterized by gapless electronic excitations. The zero temperature phase diagram as a function of the strength of the attractive interaction and the mixing is obtained. For simplicity and to clarify the nature of the quantum phase diagram we consider the case of s-wave pairing. -- Highlights: ► We study superconductivity in a multi-component system along the BCS–BEC crossover. ► The T=0 phase diagram exhibits different regimes for the superfluid phases. ► We find a new metallic phase with fermions coexisting with preformed pairs. ► Superconductivity is destroyed from the BEC-like regime.

  20. Novel two-component systems implied in antibiotic production in Streptomyces coelicolor.

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    Ana Yepes

    Full Text Available The abundance of two-component systems (TCSs in Streptomyces coelicolor A3(2 genome indicates their importance in the physiology of this soil bacteria. Currently, several TCSs have been related to antibiotic regulation, and the purpose in this study was the characterization of five TCSs, selected by sequence homology with the well-known absA1A2 system, that could also be associated with this important process. Null mutants of the five TCSs were obtained and two mutants (ΔSCO1744/1745 and ΔSCO4596/4597/4598 showed significant differences in both antibiotic production and morphological differentiation, and have been renamed as abr (antibiotic regulator. No detectable changes in antibiotic production were found in the mutants in the systems that include the ORFs SCO3638/3639, SCO3640/3641 and SCO2165/2166 in any of the culture conditions assayed. The system SCO1744/1745 (AbrA1/A2 was involved in negative regulation of antibiotic production, and acted also as a negative regulator of the morphological differentiation. By contrast, the system SCO4596/4597/4598 (AbrC1/C2/C3, composed of two histidine kinases and one response regulator, had positive effects on both morphological development and antibiotic production. Microarray analyses of the ΔabrC1/C2/C3 and wild-type transcriptomes revealed downregulation of actII-ORF4 and cdaR genes, the actinorhodin and calcium-dependent antibiotic pathway-specific regulators respectively. These results demonstrated the involvement of these new two-component systems in antibiotic production and morphological differentiation by different approaches. One is a pleiotropic negative regulator: abrA1/A2. The other one is a positive regulator composed of three elements, two histidine kinases and one response regulator: abrC1/C2/C3.

  1. Wave-breaking phenomena and global solutions for periodic two-component Dullin-Gottwald-Holm systems

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    Min Zhu

    2013-02-01

    Full Text Available In this article we study the initial-value problem for the periodic two-component b-family system, including a special case, when b = 2, which is referred to as the two-component Dullin-Gottwald-Holm (DGH system. We first show that the two-component b-family system can be derived from the theory of shallow-water waves moving over a linear shear flow. Then we establish several results of blow-up solutions corresponding to only wave breaking with certain initial profiles for the periodic two-component DGH system. Moreover, we determine the exact blow-up rate and lower bound of the lifespan for the system. Finally, we give a sufficient condition for the existence of the strong global solution to the periodic two-component DGH system.

  2. Regulation of virulence by a two-component system in group B streptococcus.

    Science.gov (United States)

    Jiang, Sheng-Mei; Cieslewicz, Michael J; Kasper, Dennis L; Wessels, Michael R

    2005-02-01

    Group B Streptococcus (GBS) is frequently carried in the gastrointestinal or genitourinary tract as a commensal organism, yet it has the potential to cause life-threatening infection in newborn infants, pregnant women, and individuals with chronic illness. Regulation of virulence factor expression may affect whether GBS behaves as an asymptomatic colonizer or an invasive pathogen, but little is known about how such factors are controlled in GBS. We now report the characterization of a GBS locus that encodes a two-component regulatory system similar to CsrRS (or CovRS) in Streptococcus pyogenes. Inactivation of csrR, encoding the putative response regulator, in two unrelated wild-type strains of GBS resulted in a marked increase in production of beta-hemolysin/cytolysin and a striking decrease in production of CAMP factor, an unrelated cytolytic toxin. Quantitative RNA hybridization experiments revealed that these two phenotypes were associated with a marked increase and decrease in expression of the corresponding genes, cylE and cfb, respectively. The CsrR mutant strains also displayed increased expression of scpB encoding C5a peptidase. Similar, but less marked, changes in gene expression were observed in CsrS (putative sensor component) mutants, evidence that CsrR and CsrS constitute a functional two-component system. Experimental infection studies in mice demonstrated reduced virulence of both CsrR and CsrS mutant strains relative to the wild type. Together, these results indicate that CsrRS regulates expression of multiple GBS virulence determinants and is likely to play an important role in GBS pathogenesis. PMID:15659687

  3. Development and characterization of two-component albedo based neutron individual monitoring system using thermoluminescent detectors

    International Nuclear Information System (INIS)

    A TLD-albedo based two-component neutron individual monitoring system was developed and characterized in this work. The monitor consists of a black plastic holder, an incident neutron boron loaded shield, a moderator polyethylene body (to increase its response), two pairs of TLD-600 and TLD-700 (one pair to each component) and an adjustable belt. This monitoring system was calibrated in thermal neutron fields and in 70 keV, 144 keV, 565 keV, 1.2 MeV and 5 MeV monoenergetic neutron fields. In addition, it was calibrated in 252Cf(D2O), 252Cf, 241Am-B, 241Am-Be and 238Pu-Be source fields. For the latter, the lower detection levels are, respectively, 0.009 mSv, 0.06 mSv, 0.12 mSv, 0.09 mSv and 0.08 mSv. The participation in an international intercomparison sponsored by IAEA with simulated workplace fields validated the system. The monitoring system was successfully characterized in the ISO 21909 standard and in an IRD - the Brazilian Institute for Radioprotection and Dosimetry - technical regulation draft. Nowadays, the neutron individual system is in use by IRD for whole body individual monitoring of five institutions, which comprehend several activities. (author)

  4. The CpxRA two-component system contributes to Legionella pneumophila virulence.

    Science.gov (United States)

    Tanner, Jennifer R; Li, Laam; Faucher, Sébastien P; Brassinga, Ann Karen C

    2016-06-01

    The bacterium Legionella pneumophila is capable of intracellular replication within freshwater protozoa as well as human macrophages, the latter of which results in the serious pneumonia Legionnaires' disease. A primary factor involved in these host cell interactions is the Dot/Icm Type IV secretion system responsible for translocating effector proteins needed to establish and maintain the bacterial replicative niche. Several regulatory factors have been identified to control the expression of the Dot/Icm system and effectors, one of which is the CpxRA two-component system, suggesting essentiality for virulence. In this study, we generated cpxR, cpxA and cpxRA in-frame null mutant strains to further delineate the role of the CpxRA system in bacterial survival and virulence. We found that cpxR is essential for intracellular replication within Acanthamoeba castellanii, but not in U937-derived macrophages. Transcriptome analysis revealed that CpxRA regulates a large number of virulence-associated proteins including Dot/Icm effectors as well as Type II secreted substrates. Furthermore, the cpxR and cpxRA mutant strains were more sodium resistant than the parental strain Lp02, and cpxRA expression reaches maximal levels during postexponential phase. Taken together, our findings suggest the CpxRA system is a key contributor to L. pneumophila virulence in protozoa via virulence factor regulation. PMID:26934669

  5. Photoisomerization-induced morphology and transparency transition in an azobenzene based two-component organogel system.

    Science.gov (United States)

    Cao, Xinhua; Liu, Xue; Chen, Liming; Mao, Yueyuan; Lan, Haichuang; Yi, Tao

    2015-11-15

    A two-component gel containing long chain alkylated gallic acid (GA) and photochromic phenazopyridine (PAP) was prepared. The gel was thoroughly characterized by UV-visible and IR spectra, SEM and POM images, XRD diffraction and dynamic oscillatory measurements. The structure and transparency of the two-component gel can be reversibly changed by alternative UV light irradiation and warming in the palm of the hand. This kind of soft material has potential application in upscale surface functional materials. PMID:26218198

  6. The Evolution of Two-Component Systems in Bacteria RevealsDifferent Strategies for Niche Adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Alm, Eric; Huang, Katherine; Arkin, Adam

    2006-09-13

    Two-component systems including histidine protein kinasesrepresent the primary signal transduction paradigm in prokaryoticorganisms. To understand how these systems adapt to allow organisms todetect niche-specific signals, we analyzed the phylogenetic distributionof nearly 5000 histidine protein kinases from 207 sequenced prokaryoticgenomes. We found that many genomes carry a large repertoire of recentlyevolved signaling genes, which may reflect selective pressure to adapt tonew environmental conditions. Both lineage-specific gene family expansionand horizontal gene transfer play major roles in the introduction of newhistidine kinases into genomes; however, there are differences in howthese two evolutionary forces act. Genes imported via horizontal transferare more likely to retain their original functionality as inferred from asimilar complement of signaling domains, while gene family expansionaccompanied by domain shuffling appears to be a major source of novelgenetic diversity. Family expansion is the dominantsource of newhistidine kinase genes in the genomes most enriched in signalingproteins, and detailed analysis reveals that divergence in domainstructure and changes in expression patterns are hallmarks of recentexpansions. Finally, while these two modes of gene acquisition arewidespread across bacterial taxa, there are clear species-specificpreferences for which mode is used.

  7. Gene Regulation by the LiaSR Two-Component System in Streptococcus mutans.

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    Manoharan Shankar

    Full Text Available The LiaSR two-component signal transduction system regulates cellular responses to several environmental stresses, including those that induce cell envelope damages. Downstream regulons of the LiaSR system have been implicated in tolerance to acid, antibiotics and detergents. In the dental pathogen Streptococcus mutans, the LiaSR system is necessary for tolerance against acid, antibiotics, and cell wall damaging stresses during growth in the oral cavity. To understand the molecular mechanisms by which LiaSR regulates gene expression, we created a mutant LiaR in which the conserved aspartic acid residue (the phosphorylation site, was changed to alanine residue (D58A. As expected, the LiaR-D58A variant was unable to acquire the phosphate group and bind to target promoters. We also noted that the predicted LiaR-binding motif upstream of the lia operon does not appear to be well conserved. Consistent with this observation, we found that LiaR was unable to bind to the promoter region of lia; however, we showed that LiaR was able to bind to the promoters of SMU.753, SMU.2084 and SMU.1727. Based on sequence analysis and DNA binding studies we proposed a new 25-bp conserved motif essential for LiaR binding. Introducing alterations at fully conserved positions in the 25-bp motif affected LiaR binding, and the binding was dependent on the combination of positions that were altered. By scanning the S. mutans genome for the occurrence of the newly defined LiaR binding motif, we identified the promoter of hrcA (encoding a key regulator of the heat shock response that contains a LiaR binding motif, and we showed that hrcA is negatively regulated by the LiaSR system. Taken together our results suggest a putative role of the LiaSR system in heat shock responses of S. mutans.

  8. Transcriptome analysis of the Brucella abortus BvrR/BvrS two-component regulatory system.

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    Cristina Viadas

    Full Text Available BACKGROUND: The two-component BvrR/BvrS system is essential for Brucella abortus virulence. It was shown previously that its dysfunction alters the expression of some major outer membrane proteins and the pattern of lipid A acylation. To determine the genes regulated by BvrR/BvrS, we performed a whole-genome microarray analysis using B. abortus RNA obtained from wild type and bvrR mutant cells grown in the same conditions. METHODOLOGY/PRINCIPAL FINDINGS: A total of 127 differentially expressed genes were found: 83 were over expressed and 44 were less expressed in the bvrR mutant. Two operons, the phosphotransferase system and the maltose transport system, were down-regulated. Several genes involved in cell envelope or outer membrane biogenesis were differentially expressed: genes for outer membrane proteins (omp25a, omp25d, lipoproteins, LPS and fatty acid biosynthesis, stress response proteins, chaperones, flagellar genes, and twelve genes encoding ABC transport systems. Ten genes related with carbon metabolism (pckA and fumB among others were up-regulated in the bvrR mutant, and denitrification genes (nirK, norC and nosZ were also regulated. Notably, seven transcriptional regulators were affected, including VjbR, ExoR and OmpR that were less expressed in the bvrR mutant. Finally, the expression of eleven genes which have been previously related with Brucella virulence was also altered. CONCLUSIONS/SIGNIFICANCE: All these data corroborate the impact of BvrR/BvrS on cell envelope modulation, confirm that this system controls the carbon and nitrogen metabolism, and suggest a cross-talk among some regulators to adjust the Brucella physiology to the shift expected to occur during the transit from the extracellular to the intracellular niche.

  9. Relating gene expression data on two-component systems to functional annotations in Escherichia coli

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    Sule Preeti

    2008-06-01

    Full Text Available Abstract Background Obtaining physiological insights from microarray experiments requires computational techniques that relate gene expression data to functional information. Traditionally, this has been done in two consecutive steps. The first step identifies important genes through clustering or statistical techniques, while the second step assigns biological functions to the identified groups. Recently, techniques have been developed that identify such relationships in a single step. Results We have developed an algorithm that relates patterns of gene expression in a set of microarray experiments to functional groups in one step. Our only assumption is that patterns co-occur frequently. The effectiveness of the algorithm is demonstrated as part of a study of regulation by two-component systems in Escherichia coli. The significance of the relationships between expression data and functional annotations is evaluated based on density histograms that are constructed using product similarity among expression vectors. We present a biological analysis of three of the resulting functional groups of proteins, develop hypotheses for further biological studies, and test one of these hypotheses experimentally. A comparison with other algorithms and a different data set is presented. Conclusion Our new algorithm is able to find interesting and biologically meaningful relationships, not found by other algorithms, in previously analyzed data sets. Scaling of the algorithm to large data sets can be achieved based on a theoretical model.

  10. Functional characterization of WalRK: A two-component signal transduction system from Bacillus anthracis

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    Alisha Dhiman

    2014-01-01

    Full Text Available Two-component signal transduction systems (TCS, consisting of a sensor histidine protein kinase and its cognate response regulator, are an important mode of environmental sensing in bacteria. Additionally, they have been found to regulate virulence determinants in several pathogens. Bacillus anthracis, the causative agent of anthrax and a bioterrorism agent, harbours 41 pairs of TCS. However, their role in its pathogenicity has remained largely unexplored. Here, we show that WalRK of B. anthracis forms a functional TCS which exhibits some species-specific functions. Biochemical studies showed that domain variants of WalK, the histidine kinase, exhibit classical properties of autophosphorylation and phosphotransfer to its cognate response regulator WalR. Interestingly, these domain variants also show phosphatase activity towards phosphorylated WalR, thereby making WalK a bifunctional histidine kinase/phosphatase. An in silico regulon determination approach, using a consensus binding sequence from Bacillus subtilis, provided a list of 30 genes that could form a putative WalR regulon in B. anthracis. Further, electrophoretic mobility shift assay was used to show direct binding of purified WalR to the upstream regions of three putative regulon candidates, an S-layer protein EA1, a cell division ABC transporter FtsE and a sporulation histidine kinase KinB3. Our work lends insight into the species-specific functions and mode of action of B. anthracis WalRK.

  11. Genome-Wide Identification and Expression Analysis of Two-Component System Genes in Tomato

    Science.gov (United States)

    He, Yanjun; Liu, Xue; Ye, Lei; Pan, Changtian; Chen, Lifei; Zou, Tao; Lu, Gang

    2016-01-01

    The two-component system (TCS), which comprises histidine kinases (HKs), phosphotransfers (HPs), and response regulator proteins (RRs), plays pivotal roles in regulating plant growth, development, and responses to biotic and abiotic stresses. TCS genes have been comprehensively identified and investigated in various crops but poorly characterized in tomato. In this work, a total of 65 TCS genes consisting of 20 HK(L)s, six HPs, and 39 RRs were identified from tomato genome. The classification, gene structures, conserved domains, chromosome distribution, phylogenetic relationship, gene duplication events, and subcellular localization of the TCS gene family were predicted and analyzed in detail. The amino acid sequences of tomato TCS family members, except those of type-B RRs, are highly conserved. The gene duplication events of the TCS family mainly occurred in the RR family. Furthermore, the expansion of RRs was attributed to both segment and tandem duplication. The subcellular localizations of the selected green fluorescent protein (GFP) fusion proteins exhibited a diverse subcellular targeting, thereby confirming their predicted divergent functionality. The majority of TCS family members showed distinct organ- or development-specific expression patterns. In addition, most of TCS genes were induced by abiotic stresses and exogenous phytohormones. The full elucidation of TCS elements will be helpful for comprehensive analysis of the molecular biology and physiological role of the TCS superfamily. PMID:27472316

  12. Site-Directed Mutagenesis to Improve Sensitivity of a Synthetic Two-Component Signaling System.

    Science.gov (United States)

    Olshefsky, Audrey; Shehata, Laila; Kuldell, Natalie

    2016-01-01

    Two-component signaling (2CS) systems enable bacterial cells to respond to changes in their local environment, often using a membrane-bound sensor protein and a cytoplasmic responder protein to regulate gene expression. Previous work has shown that Escherichia coli's natural EnvZ/OmpR 2CS could be modified to construct a light-sensing bacterial photography system. The resulting bacterial photographs, or "coliroids," rely on a phosphotransfer reaction between Cph8, a synthetic version of EnvZ that senses red light, and OmpR. Gene expression changes can be visualized through upregulation of a LacZ reporter gene by phosphorylated OmpR. Unfortunately, basal LacZ expression leads to a detectable reporter signal even when cells are grown in the light, diminishing the contrast of the coliroids. We performed site-directed mutagenesis near the phosphotransfer site of Cph8 to isolate mutants with potentially improved image contrast. Five mutants were examined, but only one of the mutants, T541S, increased the ratio of dark/light gene expression, as measured by β-galactosidase activity. The ratio changed from 2.57 fold in the starting strain to 5.59 in the T541S mutant. The ratio decreased in the four other mutant strains we examined. The phenotype observed in the T541S mutant strain may arise because the serine sidechain is chemically similar but physically smaller than the threonine sidechain. This may minimally change the protein's local structure, but may be less sterically constrained when compared to threonine, resulting in a higher probability of a phosphotransfer event. Our initial success pairing synthetic biology and site-directed mutagenesis to optimize the bacterial photography system's performance encourages us to imagine further improvements to the performance of this and other synthetic systems, especially those based on 2CS signaling. PMID:26799494

  13. Characterization of an archaeal two-component system that regulates methanogenesis in Methanosaeta harundinacea.

    Directory of Open Access Journals (Sweden)

    Jie Li

    Full Text Available Two-component signal transduction systems (TCSs are a major mechanism used by bacteria in response to environmental changes. Although many sequenced archaeal genomes encode TCSs, they remain poorly understood. Previously, we reported that a methanogenic archaeon, Methanosaeta harundinacea, encodes FilI, which synthesizes carboxyl-acyl homoserine lactones, to regulate transitions of cellular morphology and carbon metabolic fluxes. Here, we report that filI, the cotranscribed filR2, and the adjacent filR1 constitute an archaeal TCS. FilI possesses a cytoplasmic kinase domain (histidine kinase A and histidine kinase-like ATPase and its cognate response regulator. FilR1 carries a receiver (REC domain coupled with an ArsR-related domain with potential DNA-binding ability, while FilR2 carries only a REC domain. In a phosphorelay assay, FilI was autophosphorylated and specifically transferred the phosphoryl group to FilR1 and FilR2, confirming that the three formed a cognate TCS. Through chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR using an anti-FilR1 antibody, FilR1 was shown to form in vivo associations with its own promoter and the promoter of the filI-filR2 operon, demonstrating a regulatory pattern common among TCSs. ChIP-qPCR also detected FilR1 associations with key genes involved in acetoclastic methanogenesis, acs4 and acs1. Electrophoretic mobility shift assays confirmed the in vitro tight binding of FilR1 to its own promoter and those of filI-filR2, acs4, and mtrABC. This also proves the DNA-binding ability of the ArsR-related domain, which is found primarily in Archaea. The archaeal promoters of acs4, filI, acs1, and mtrABC also initiated FilR1-modulated expression in an Escherichia coli lux reporter system, suggesting that FilR1 can up-regulate both archaeal and bacterial transcription. In conclusion, this work identifies an archaeal FilI/FilRs TCS that regulates the methanogenesis of M. harundinacea.

  14. The Two-Component Virial Theorem and the Physical Properties of Stellar Systems

    OpenAIRE

    Dantas, Christine C.; Ribeiro, Andre L. B.; Capelato, Hugo V.; de Carvalho, Reinaldo R.

    1999-01-01

    Motivated by present indirect evidences that galaxies are surrounded by dark matter halos, we investigate whether their physical properties can be described by a formulation of the virial theorem which explicitly takes into account the gravitational potential term representing the interaction of the dark halo with the barionic or luminous component. Our analysis shows that the application of such a ``two-component virial theorem'' not only accounts for the scaling relations displayed, in part...

  15. Phenotype microarray analysis of Escherichia coli K-12 mutants with deletions of all two-component systems.

    Science.gov (United States)

    Zhou, Lu; Lei, Xiang-He; Bochner, Barry R; Wanner, Barry L

    2003-08-01

    Two-component systems are the most common mechanism of transmembrane signal transduction in bacteria. A typical system consists of a histidine kinase and a partner response regulator. The histidine kinase senses an environmental signal, which it transmits to its partner response regulator via a series of autophosphorylation, phosphotransfer, and dephosphorylation reactions. Much work has been done on particular systems, including several systems with regulatory roles in cellular physiology, communication, development, and, in the case of bacterial pathogens, the expression of genes important for virulence. We used two methods to investigate two-component regulatory systems in Escherichia coli K-12. First, we systematically constructed mutants with deletions of all two-component systems by using a now-standard technique of gene disruption (K. A. Datsenko and B. L. Wanner, Proc. Natl. Acad. Sci. USA 97:6640-6645, 2000). We then analyzed these deletion mutants with a new technology called Phenotype MicroArrays, which permits assays of nearly 2,000 growth phenotypes simultaneously. In this study we tested 100 mutants, including mutants with individual deletions of all two-component systems and several related genes, including creBC-regulated genes (cbrA and cbrBC), phoBR-regulated genes (phoA, phoH, phnCDEFGHIJKLMNOP, psiE, and ugpBAECQ), csgD, luxS, and rpoS. The results of this battery of nearly 200,000 tests provided a wealth of new information concerning many of these systems. Of 37 different two-component mutants, 22 showed altered phenotypes. Many phenotypes were expected, and several new phenotypes were also revealed. The results are discussed in terms of the biological roles and other information concerning these systems, including DNA microarray data for a large number of the same mutants. Other mutational effects are also discussed. PMID:12897016

  16. Bacillus subtilis Two-Component System Sensory Kinase DegS Is Regulated by Serine Phosphorylation in Its Input Domain

    DEFF Research Database (Denmark)

    Jers, Carsten; Kobir, Ahasanul; Søndergaard, Elsebeth Oline;

    2011-01-01

    Bacillus subtilis two-component system DegS/U is well known for the complexity of its regulation. The cytosolic sensory kinase DegS does not receive a single predominant input signal like most two-component kinases, instead it integrates a wide array of metabolic inputs that modulate its activity...... demonstrate that DegS phosphorylation can be carried out by at least two B. subtilis Hanks-type kinases in vitro, and this stimulates the phosphate transfer towards DegU. The consequences of this process were studied in vivo, using phosphomimetic (Ser76Asp) and non-phosphorylatable (Ser76Ala) mutants of Deg...

  17. Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

    NARCIS (Netherlands)

    Been, M.W.H.J. de; Francke, C.; Moezelaar, R.; Abee, T.; Siezen, R.J.

    2006-01-01

    Members of the Bacillus cereus group are ubiquitously present in the environment and can adapt to a wide range of environmental fluctuations. In bacteria, these adaptive responses are generally mediated by two-component signal transduction systems (TCSs), which consist of a histidine kinase (HK) and

  18. Vortices with scalar condensates in two-component Ginzburg-Landau systems

    CERN Document Server

    Forgacs, Peter

    2016-01-01

    In a class of two-component Ginzburg-Landau models (TCGL) with a U(1)$\\times$U(1) symmetric potential, vortices with a condensate at their core may have significantly lower energies than the Abrikosov-Nielsen-Olesen (ANO) ones. On the example of liquid metallic hydrogen (LMH) above the critical temperature for protons we show that the ANO vortices become unstable against core-condensation, while condensate-core (CC) vortices are stable. For LMH the ratio of the masses of the two types of condensates, $M=m_2/m_1$ is large, and then as a consequence the energy per flux quantum of the vortices, $E_n/n$ becomes a non-monotonous function of the number of flux quanta, $n$. This leads to yet another manifestation of neither type 1 nor type 2, (type 1.5) superconductivity: superconducting and normal domains coexist while various "giant" vortices form. We note that LMH provides a particularly clean example of type 1.5 state as the interband coupling between electronic and protonic Cooper-pairs is forbidden.

  19. Phosphate sink containing two-component signaling systems as tunable threshold devices

    DEFF Research Database (Denmark)

    Amin, Munia; Kothamachu, Varun B; Feliu, Elisenda;

    2014-01-01

    Synthetic biology aims to design de novo biological systems and reengineer existing ones. These efforts have mostly focused on transcriptional circuits, with reengineering of signaling circuits hampered by limited understanding of their systems dynamics and experimental challenges. Bacterial two...

  20. Some new integrable systems of two-component fifth order equations

    OpenAIRE

    Talati, Daryoush; Wazwaz, Abdul-Majid

    2016-01-01

    In this work we develop some fifth-order integrable coupled systems of weight $0$ and $1$ which possess seventh-order symmetry. We establish four new systems, where in some cases, related recursion operator and bi-Hamiltonian formulations are given. We also investigate the integrability of the developed systems.

  1. Two-component signal transduction pathways regulating growth and cell cycle progression in a bacterium: a system-level analysis.

    Directory of Open Access Journals (Sweden)

    Jeffrey M Skerker

    2005-10-01

    Full Text Available Two-component signal transduction systems, comprised of histidine kinases and their response regulator substrates, are the predominant means by which bacteria sense and respond to extracellular signals. These systems allow cells to adapt to prevailing conditions by modifying cellular physiology, including initiating programs of gene expression, catalyzing reactions, or modifying protein-protein interactions. These signaling pathways have also been demonstrated to play a role in coordinating bacterial cell cycle progression and development. Here we report a system-level investigation of two-component pathways in the model organism Caulobacter crescentus. First, by a comprehensive deletion analysis we show that at least 39 of the 106 two-component genes are required for cell cycle progression, growth, or morphogenesis. These include nine genes essential for growth or viability of the organism. We then use a systematic biochemical approach, called phosphotransfer profiling, to map the connectivity of histidine kinases and response regulators. Combining these genetic and biochemical approaches, we identify a new, highly conserved essential signaling pathway from the histidine kinase CenK to the response regulator CenR, which plays a critical role in controlling cell envelope biogenesis and structure. Depletion of either cenK or cenR leads to an unusual, severe blebbing of cell envelope material, whereas constitutive activation of the pathway compromises cell envelope integrity, resulting in cell lysis and death. We propose that the CenK-CenR pathway may be a suitable target for new antibiotic development, given previous successes in targeting the bacterial cell wall. Finally, the ability of our in vitro phosphotransfer profiling method to identify signaling pathways that operate in vivo takes advantage of an observation that histidine kinases are endowed with a global kinetic preference for their cognate response regulators. We propose that this

  2. The BaeSR Two-Component Regulatory System Mediates Resistance to Condensed Tannins in Escherichia coli▿ †

    OpenAIRE

    Zoetendal, E.G.; Smith, A H; Sundset, M.A.; Mackie, R. I.

    2007-01-01

    The gene expression profiles of Escherichia coli strains grown anaerobically with or without Acacia mearnsii (black wattle) extract were compared to identify tannin resistance strategies. The cell envelope stress protein gene spy and the multidrug transporter-encoding operon mdtABCD, both under the control of the BaeSR two-component regulatory system, were significantly up-regulated in the presence of tannins. BaeSR mutants were more tannin sensitive than their wild-type counterparts.

  3. Genome-wide survey of two-component signal transduction systems in the plant growth-promoting bacterium Azospirillum

    OpenAIRE

    Borland, Stéphanie; Oudart, Anne; Prigent-Combaret, Claire; Brochier-Armanet, Céline; Wisniewski-Dyé, Florence

    2015-01-01

    Background Two-component systems (TCS) play critical roles in sensing and responding to environmental cues. Azospirillum is a plant growth-promoting rhizobacterium living in the rhizosphere of many important crops. Despite numerous studies about its plant beneficial properties, little is known about how the bacterium senses and responds to its rhizospheric environment. The availability of complete genome sequenced from four Azospirillum strains (A. brasilense Sp245 and CBG 497, A. lipoferum 4...

  4. Two-Component Systems of Mycobacterium tuberculosis—Structure-Based Approaches

    DEFF Research Database (Denmark)

    Tucker, Paul; Nowak, Elzbieta; Morth, Jens Preben

    Mycobacterium tuberculosis contains few two‐component systems compared to many other bacteria, possibly because it has more serine/threonine signaling pathways. Even so, these two‐component systems appear to play an important role in early intracellular survival of the pathogen as well as in...

  5. A two-component preceramic polymer system for structured coatings on metals

    International Nuclear Information System (INIS)

    A liquid polysiloxane system consisting of a polymethoxymethylsiloxan and a hydroxy-terminated linear polysiloxane was used as preceramic polymer coatings on stainless steel. Interface reactions between the polymer derived ceramic matrix and the steel substrate were evaluated during and after pyrolysis with X-ray diffraction analysis and energy dispersive X-ray analysis. The system was loaded with different fillers and the rheological behaviour was investigated with respect to the coating thickness evolution by dip coating processing. Interface reactions with the steel components such as carbide formation and spinel formation were detected in the filler-free system and shear thinning was found to be a useful tool for coating thickness adjustment.

  6. Solution of thermal neutron diffusion equation for the two-component system by perturbation calculation

    International Nuclear Information System (INIS)

    A method of solving the diffusion equation for the th ermal neutron flux in a heterogeneous medium is presented. Perturbation calculation is successfully applied for the cylindrical concentric system after testing this method for the spherical concentric geometry analytically solved by Czubek (1981). The method permits to calculate the t hermal neutron decay constant and the space distribution of the thermal neutron flux in a heterogeneous geom etry. The condition of the constant value of the neutron flux in the inner part of the system has to be m et. This method has an application in the measurement of the thermal neutron absorption cross section, presented by Czubek (1981). (author)

  7. SELF-SIMILAR SOLUTIONS AND BLOW-UP PHENOMENA FOR A TWO-COMPONENT SHALLOW WATER SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Shouming ZHOU; Chunlai MU; Liangchen WANG

    2013-01-01

    In this article,we consider a two-component nonlinear shallow water system,which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases.The local well-posedess for this equations is established.Some sufficient conditions for blow-up of the solutions in finite time are given.Moreover,by separation method,the self-similar solutions for the nonlinear shallow water equations are obtained,and which local or global behavior can be determined by the corresponding Emden equation.

  8. The CsrR/CsrS two-component system of group A Streptococcus responds to environmental Mg2+

    OpenAIRE

    Gryllos, Ioannis; Levin, James C.; Wessels, Michael R.

    2003-01-01

    Group A streptococci control expression of key virulence determinants via the two-component sensor/regulator system CsrR/CsrS. The membrane-bound sensor CsrS is thought to respond to previously unknown environmental signal(s) by controlling phosphorylation of its cognate regulator component CsrR. Phosphorylation of CsrR increases its affinity for binding to the promoter regions of Csr-regulated genes to repress transcription. Here we show that environmental Mg2+ concentration is a potent and ...

  9. Two-Component Regulatory Systems – implication in the quorum sensing mechanisms and bacteriocin production in lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Lia–Mara Ditu

    2014-08-01

    Full Text Available For lactic acid bacteria, the mechanisms of quorum sensing and response are mediated by peptides or pheromones that interfere with the synthesis of antimicrobial peptides (AMP called bacteriocins, when these molecules reach a certain critical level of concentration. Generally, the synthesis and activity of pheromones is adjusted by means of a two-component regulatory system. The observation that some microorganisms, in particular lactic acid bacteria, produce bacteriocins according to the cell density, has led to the discovery of the involvement of QS mechanisms in the synthesis of these peptides. Bacteriocins synthesis is inducible, the process requiring the extracellular accumulation of peptides that functions as chemical messengers activators of bacteriocins synthesis. This minireview presents the molecular architecture and functions of two-component regulatory systems and ABC transporters implicated in the synthesis and secretion of nisin, one of the most studied bacteriocin. The elucidation of the intimate mechanisms of bacteriocins synthesis is equally of biotechnological and medical importance, opening interesting perspectives for the development of improved technologies for the production of bacteriocins with good yields, and also, for increasing the beneficial anti-infective roles of probiotic bacteria when administered in vivo.

  10. Characterization of a two-component system in Streptococcus pyogenes which is involved in regulation of hyaluronic acid production.

    Science.gov (United States)

    Bernish, B; van de Rijn, I

    1999-02-19

    Hyaluronic acid production by group A streptococci is regulated by transcriptional control. In this study, transposon mutagenesis of an unencapsulated strain yielded an encapsulated mutant. Two genes homologous to sensors and response regulators of bacterial two-component systems were identified downstream of the transposon insertion. Inactivation of the putative sensor gene, csrS, in three different unencapsulated strains yielded encapsulated mutant strains. Electrophoretic mobility shift assays determined factor(s) in a cytoplasmic extract of an unencapsulated group A streptococcal strain was binding to a double-stranded DNA fragment derived from the has operon promoter. In contrast, similarly prepared cytoplasmic extracts from a csrS deletion mutant did not shift the fragment. The putative response regulator, CsrR, was partially purified and was shown to bind the has operon promoter fragment. The affinity and specificity of CsrR for the fragment were increased significantly after incubation with acetyl phosphate. DNase I footprinting determined that the acetyl phosphate-treated CsrR was binding to key sequences in the promoter and the coding region of hasA. Therefore, a two-component system is repressing the production of hyaluronic acid in group A streptococci using a phosphorylation-dependent binding interaction between the response regulator CsrR and the promoter region of the has operon. PMID:9988717

  11. Origin and evolution of two-component debris discs and an application to the q1 Eridani system

    Science.gov (United States)

    Schüppler, Christian; Krivov, Alexander V.; Löhne, Torsten; Booth, Mark; Kirchschlager, Florian; Wolf, Sebastian

    2016-09-01

    Many debris discs reveal a two-component structure, with an outer Kuiper-belt analogue and a warm inner component whose origin is still a matter of debate. One possibility is that warm emission stems from an `asteroid belt' closer in to the star. We consider a scenario in which a set of giant planets is formed in an initially extended planetesimal disc. These planets carve a broad gap around their orbits, splitting up the disc into the outer and the inner belts. After the gas dispersal, both belts undergo collisional evolution in a steady-state regime. This scenario is explored with detailed collisional simulations involving realistic physics to describe a long-term collisional depletion of the two-component disc. We find that the inner disc may be able to retain larger amounts of material at older ages than thought before on the basis of simplified analytic models. We show that the proposed scenario is consistent with a suite of thermal emission and scattered light observational data for a bright two-temperature debris disc around a nearby solar-type star q1 Eridani. This implies a Solar system-like architecture of the system, with an outer massive `Kuiper belt', an inner `asteroid belt', and a few Neptune- to Jupiter-mass planets in between.

  12. A two-component system regulates the expression of an ABC transporter for xylo-oligosaccharides in Geobacillus stearothermophilus.

    Science.gov (United States)

    Shulami, Smadar; Zaide, Galia; Zolotnitsky, Gennady; Langut, Yael; Feld, Geoff; Sonenshein, Abraham L; Shoham, Yuval

    2007-02-01

    Geobacillus stearothermophilus T-6 utilizes an extensive and highly regulated hemicellulolytic system. The genes comprising the xylanolytic system are clustered in a 39.7-kb chromosomal segment. This segment contains a 6-kb transcriptional unit (xynDCEFG) coding for a potential two-component system (xynDC) and an ATP-binding cassette (ABC) transport system (xynEFG). The xynD promoter region contains a 16-bp inverted repeat resembling the operator site for the xylose repressor, XylR. XylR was found to bind specifically to this sequence, and binding was efficiently prevented in vitro in the presence of xylose. The ABC transport system was shown to comprise an operon of three genes (xynEFG) that is transcribed from its own promoter. The nonphosphorylated fused response regulator, His6-XynC, bound to a 220-bp fragment corresponding to the xynE operator. DNase I footprinting analysis showed four protected zones that cover the -53 and the +34 regions and revealed direct repeat sequences of a GAAA-like motif. In vitro transcriptional assays and quantitative reverse transcription-PCR demonstrated that xynE transcription is activated 140-fold in the presence of 1.5 microM XynC. The His6-tagged sugar-binding lipoprotein (XynE) of the ABC transporter interacted with different xylosaccharides, as demonstrated by isothermal titration calorimetry. The change in the heat capacity of binding (DeltaCp) for XynE with xylotriose suggests a stacking interaction in the binding site that can be provided by a single Trp residue and a sugar moiety. Taken together, our data show that XynEFG constitutes an ABC transport system for xylo-oligosaccharides and that its transcription is negatively regulated by XylR and activated by the response regulator XynC, which is part of a two-component sensing system. PMID:17142383

  13. Two-component signal transduction system SaeRS is involved in competence and penicillin susceptibility in Staphylococcus epidermidis.

    Science.gov (United States)

    Lou, Qiang; Ma, Yuanfang; Qu, Di

    2016-04-01

    Staphylococcus epidermidis, which is a causative pathogen of nosocomial infection, expresses its virulent traits such as biofilm and autolysis regulated by two-component signal transduction system SaeRS. In this study, the S. epidermidis SaeRS was identified to negatively regulate the expression of genes involved in competence (comF, murF), cytolysis (lrgA), and autolysis (lytS) by DNA microarray or real-time RT-PCR analysis. In addition, saeRS mutant showed increased competence and higher susceptibility to antibiotics such as penicillin and oxacillin than the wild-type strain. The study will be helpful for understanding the characterization of the SaeRS in S. epidermidis. PMID:26898187

  14. Effects of the global regulator CsrA on the BarA/UvrY two-component signaling system.

    Science.gov (United States)

    Camacho, Martha I; Alvarez, Adrian F; Chavez, Ricardo Gonzalez; Romeo, Tony; Merino, Enrique; Georgellis, Dimitris

    2015-03-01

    The hybrid sensor kinase BarA and its cognate response regulator UvrY, members of the two-component signal transduction family, activate transcription of CsrB and CsrC noncoding RNAs. These two small RNAs act by sequestering the RNA binding protein CsrA, which posttranscriptionally regulates translation and/or stability of its target mRNAs. Here, we provide evidence that CsrA positively affects, although indirectly, uvrY expression, at both the transcriptional and translational levels. We also demonstrate that CsrA is required for properly switching BarA from its phosphatase to its kinase activity. Thus, the existence of a feedback loop mechanism that involves the Csr and BarA/UvrY global regulatory systems is exposed. PMID:25535275

  15. Characterization of a novel bile-inducible operon encoding a two-component regulatory system in Lactobacillus acidophilus.

    Science.gov (United States)

    Pfeiler, Erika A; Azcarate-Peril, M Andrea; Klaenhammer, Todd R

    2007-07-01

    Lactobacillus acidophilus NCFM is an industrially important strain used extensively as a probiotic culture. Tolerance of the presence of bile is an attribute important to microbial survival in the intestinal tract. A whole-genome microarray was employed to examine the effects of bile on the global transcriptional profile of this strain, with the intention of elucidating genes contributing to bile tolerance. Genes involved in carbohydrate metabolism were generally induced, while genes involved in other aspects of cellular growth were mostly repressed. A 7-kb eight-gene operon encoding a two-component regulatory system (2CRS), a transporter, an oxidoreductase, and four hypothetical proteins was significantly upregulated in the presence of bile. Deletion mutations were constructed in six genes of the operon. Transcriptional analysis of the 2CRS mutants showed that mutation of the histidine protein kinase (HPK) had no effect on the induction of the operon, whereas the mutated response regulator (RR) showed enhanced induction when the cells were exposed to bile. These results indicate that the 2CRS plays a role in bile tolerance and that the operon it resides in is negatively controlled by the RR. Mutations in the transporter, the HPK, the RR, and a hypothetical protein each resulted in loss of tolerance of bile. Mutations in genes encoding another hypothetical protein and a putative oxidoreductase resulted in significant increases in bile tolerance. This functional analysis showed that the operon encoded proteins involved in both bile tolerance and bile sensitivity. PMID:17449631

  16. Two-component system response regulators involved in virulence of Streptococcus pneumoniae TIGR4 in infective endocarditis.

    Science.gov (United States)

    Trihn, My; Ge, Xiuchun; Dobson, Alleson; Kitten, Todd; Munro, Cindy L; Xu, Ping

    2013-01-01

    Streptococci resident in the oral cavity have been linked to infective endocarditis (IE). While other viridans streptococci are commonly studied in relation to IE, less research has been focused on Streptococcus pneumoniae. We established for the first time an animal model of S. pneumoniae IE, and examined the virulence of the TIGR4 strain in this model. We hypothesized that two-component systems (TCS) may mediate S. pneumoniae TIGR4 strain virulence in IE and examined TCS response regulator (RR) mutants of TIGR4 in vivo with the IE model. Thirteen of the 14 RR protein genes were mutagenized, excluding only the essential gene SP_1227. The requirement of the 13 RRs for S. pneumoniae competitiveness in the IE model was assessed in vivo through use of quantitative real-time PCR (qPCR) and competitive index assays. Using real-time PCR, several RR mutants were detected at significantly lower levels in infected heart valves compared with a control strain suggesting the respective RRs are candidate virulence factors for IE. The virulence reduction of the ΔciaR mutant was further confirmed by competitive index assay. Our data suggest that CiaR is a virulence factor of S. pneumoniae strain TIGR4 for IE. PMID:23342132

  17. STAC--A New Domain Associated with Transmembrane Solute Transport and Two-Component Signal Transduction Systems.

    Science.gov (United States)

    Korycinski, Mateusz; Albrecht, Reinhard; Ursinus, Astrid; Hartmann, Marcus D; Coles, Murray; Martin, Jörg; Dunin-Horkawicz, Stanislaw; Lupas, Andrei N

    2015-10-01

    Transmembrane receptors are integral components of sensory pathways in prokaryotes. These receptors share a common dimeric architecture, consisting in its basic form of an N-terminal extracellular sensor, transmembrane helices, and an intracellular effector. As an exception, we have identified an archaeal receptor family--exemplified by Af1503 from Archaeoglobus fulgidus--that is C-terminally shortened, lacking a recognizable effector module. Instead, a HAMP domain forms the sole extension for signal transduction in the cytosol. Here, we examine the gene environment of Af1503-like receptors and find a frequent association with transmembrane transport proteins. Furthermore, we identify and define a closely associated new protein domain family, which we characterize structurally using Af1502 from A. fulgidus. Members of this family are found both as stand-alone proteins and as domains within extant receptors. In general, the latter appear as connectors between the solute carrier 5 (SLC5)-like transmembrane domains and two-component signal transduction (TCST) domains. This is seen, for example, in the histidine kinase CbrA, which is a global regulator of metabolism, virulence, and antibiotic resistance in Pseudomonads. We propose that this newly identified domain family mediates signal transduction in systems regulating transport processes and name it STAC, for SLC and TCST-Associated Component. PMID:26321252

  18. The Role of CzcRS Two-Component Systems in the Heavy Metal Resistance of Pseudomonas putida X4

    Directory of Open Access Journals (Sweden)

    Pulin Liu

    2015-07-01

    Full Text Available The role of different czcRS genes in metal resistance and the cross-link between czcRS and czcCBA in Pseudomonas putida X4 were studied to advance understanding of the mechanisms by which P. putida copes with metal stress. Similar to P. putida KT2440, two complete czcRS1 and czcRS2 two-component systems, as well as a czcR3 without the corresponding sensing component were amplified in P. putida X4. The histidine kinase genes czcS1 and czcS2 were inactivated and fused to lacZ by homologous recombination. The lacZ fusion assay revealed that Cd2+ and Zn2+ caused a decrease in the transcription of czcRS1, whereas Cd2+ treatment enhanced the transcription of czcRS2. The mutation of different czcRSs showed that all czcRSs are necessary to facilitate full metal resistance in P. putida X4. A putative gene just downstream of czcR3 is related to metal ion resistance, and its transcription was activated by Zn2+. Data from quantitative real-time polymerase chain reaction (qRT-PCR strongly suggested that czcRSs regulate the expression of czcCBA, and a cross-link exists between different czcRSs.

  19. The RpfCG two-component system negatively regulates the colonization of sugar cane stalks by Xanthomonas albilineans.

    Science.gov (United States)

    Rott, Philippe; Fleites, Laura A; Mensi, Imène; Sheppard, Lauren; Daugrois, Jean-Heinrich; Dow, J Maxwell; Gabriel, Dean W

    2013-06-01

    The genome of Xanthomonas albilineans, the causal agent of sugar cane leaf scald, carries a gene cluster encoding a predicted quorum sensing system that is highly related to the diffusible signalling factor (DSF) systems of the plant pathogens Xylella fastidiosa and Xanthomonas campestris. In these latter pathogens, a cluster of regulation of pathogenicity factors (rpf) genes encodes the DSF system and is involved in control of various cellular processes. Mutation of Xanthomonas albilineans rpfF, encoding a predicted DSF synthase, in Florida strain XaFL07-1 resulted in a small reduction of disease severity (DS). Single-knockout mutations of rpfC and rpfG (encoding a predicted DSF sensor and regulator, respectively) had no effect on DS or swimming motility of the pathogen. However, capacity of the pathogen to cause disease was slightly reduced and swimming motility was severely affected when rpfG and rpfC were both deleted. Similar results were obtained when the entire rpfGCF region was deleted. Surprisingly, when the pathogen was mutated in rpfG or rpfC (single or double mutations) it was able to colonize sugar cane spatially more efficiently than the wild-type. Mutation in rpfF alone did not affect the degree of spatial invasion. We conclude that the DSF signal contributes to symptom expression but not to invasion of sugar cane stalks by Xanthomonas albilineans strain XaFL07-1, which is mainly controlled by the RpfCG two-component system. PMID:23538716

  20. CovS/CovR of group B streptococcus: a two-component global regulatory system involved in virulence.

    Science.gov (United States)

    Lamy, Marie-Cécile; Zouine, Mohammed; Fert, Juliette; Vergassola, Massimo; Couve, Elisabeth; Pellegrini, Elisabeth; Glaser, Philippe; Kunst, Frank; Msadek, Tarek; Trieu-Cuot, Patrick; Poyart, Claire

    2004-12-01

    In this study, we carried out a detailed structural and functional analysis of a Streptococcus agalactiae (GBS) two-component system which is orthologous to the CovS/CovR (CsrS/CsrR) regulatory system of Streptococcus pyogenes. In GBS, covR and covS are part of a seven gene operon transcribed from two promoters that are not regulated by CovR. A DeltacovSR mutant was found to display dramatic phenotypic changes such as increased haemolytic activity and reduced CAMP activity on blood agar. Adherence of the DeltacovSR mutant to epithelial cells was greatly increased and analysis by transmission electron microscopy revealed the presence at its surface of a fibrous extracellular matrix that might be involved in these intercellular interactions. However, the DeltacovSR mutant was unable to initiate growth in RPMI and its viability in human normal serum was greatly impaired. A major finding of this phenotypic analysis was that the CovS/CovR system is important for GBS virulence, as a 3 log increase of the LD(50) of the mutant strain was observed in the neonate rat sepsis model. The pleiotropic phenotype of the DeltacovSR mutant is in full agreement with the large number of genes controlled by CovS/CovR as seen by expression profiling analysis, many of which encode potentially secreted or cell surface-associated proteins: 76 genes are repressed whereas 63 were positively regulated. CovR was shown to bind directly to the regulatory regions of several of these genes and a consensus CovR recognition sequence was proposed using both DNase I footprinting and computational analyses. PMID:15554966

  1. A two-component system regulates gene expression of the type IX secretion component proteins via an ECF sigma factor.

    Science.gov (United States)

    Kadowaki, Tomoko; Yukitake, Hideharu; Naito, Mariko; Sato, Keiko; Kikuchi, Yuichiro; Kondo, Yoshio; Shoji, Mikio; Nakayama, Koji

    2016-01-01

    The periodontopathogen Porphyromonas gingivalis secretes potent pathogenic proteases, gingipains, via the type IX secretion system (T9SS). This system comprises at least 11 components; however, the regulatory mechanism of their expression has not yet been elucidated. Here, we found that the PorY (PGN_2001)-PorX (PGN_1019)-SigP (PGN_0274) cascade is involved in the regulation of T9SS. Surface plasmon resonance (SPR) analysis revealed a direct interaction between a recombinant PorY (rPorY) and a recombinant PorX (rPorX). rPorY autophosphorylated and transferred a phosphoryl group to rPorX in the presence of Mn(2+). These results demonstrate that PorX and PorY act as a response regulator and a histidine kinase, respectively, of a two component system (TCS), although they are separately encoded on the chromosome. T9SS component-encoding genes were down-regulated in a mutant deficient in a putative extracytoplasmic function (ECF) sigma factor, PGN_0274 (SigP), similar to the porX mutant. Electrophoretic gel shift assays showed that rSigP bound to the putative promoter regions of T9SS component-encoding genes. The SigP protein was lacking in the porX mutant. Co-immunoprecipitation and SPR analysis revealed the direct interaction between SigP and PorX. Together, these results indicate that the PorXY TCS regulates T9SS-mediated protein secretion via the SigP ECF sigma factor. PMID:26996145

  2. A two-component system regulates gene expression of the type IX secretion component proteins via an ECF sigma factor

    Science.gov (United States)

    Kadowaki, Tomoko; Yukitake, Hideharu; Naito, Mariko; Sato, Keiko; Kikuchi, Yuichiro; Kondo, Yoshio; Shoji, Mikio; Nakayama, Koji

    2016-01-01

    The periodontopathogen Porphyromonas gingivalis secretes potent pathogenic proteases, gingipains, via the type IX secretion system (T9SS). This system comprises at least 11 components; however, the regulatory mechanism of their expression has not yet been elucidated. Here, we found that the PorY (PGN_2001)-PorX (PGN_1019)-SigP (PGN_0274) cascade is involved in the regulation of T9SS. Surface plasmon resonance (SPR) analysis revealed a direct interaction between a recombinant PorY (rPorY) and a recombinant PorX (rPorX). rPorY autophosphorylated and transferred a phosphoryl group to rPorX in the presence of Mn2+. These results demonstrate that PorX and PorY act as a response regulator and a histidine kinase, respectively, of a two component system (TCS), although they are separately encoded on the chromosome. T9SS component-encoding genes were down-regulated in a mutant deficient in a putative extracytoplasmic function (ECF) sigma factor, PGN_0274 (SigP), similar to the porX mutant. Electrophoretic gel shift assays showed that rSigP bound to the putative promoter regions of T9SS component-encoding genes. The SigP protein was lacking in the porX mutant. Co-immunoprecipitation and SPR analysis revealed the direct interaction between SigP and PorX. Together, these results indicate that the PorXY TCS regulates T9SS-mediated protein secretion via the SigP ECF sigma factor. PMID:26996145

  3. Two-component system cross-regulation integrates Bacillus anthracis response to heme and cell envelope stress.

    Directory of Open Access Journals (Sweden)

    Laura A Mike

    2014-03-01

    Full Text Available Two-component signaling systems (TCSs are one of the mechanisms that bacteria employ to sense and adapt to changes in the environment. A prototypical TCS functions as a phosphorelay from a membrane-bound sensor histidine kinase (HK to a cytoplasmic response regulator (RR that controls target gene expression. Despite significant homology in the signaling domains of HKs and RRs, TCSs are thought to typically function as linear systems with little to no cross-talk between non-cognate HK-RR pairs. Here we have identified several cell envelope acting compounds that stimulate a previously uncharacterized Bacillus anthracis TCS. Furthermore, this TCS cross-signals with the heme sensing TCS HssRS; therefore, we have named it HssRS interfacing TCS (HitRS. HssRS reciprocates cross-talk to HitRS, suggesting a link between heme toxicity and cell envelope stress. The signaling between HssRS and HitRS occurs in the parental B. anthracis strain; therefore, we classify HssRS-HitRS interactions as cross-regulation. Cross-talk between HssRS and HitRS occurs at both HK-RR and post-RR signaling junctions. Finally, HitRS also regulates a previously unstudied ABC transporter implicating this transporter in the response to cell envelope stress. This chemical biology approach to probing TCS signaling provides a new model for understanding how bacterial signaling networks are integrated to enable adaptation to complex environments such as those encountered during colonization of the vertebrate host.

  4. The CsrR/CsrS two-component system of group A Streptococcus responds to environmental Mg2+.

    Science.gov (United States)

    Gryllos, Ioannis; Levin, James C; Wessels, Michael R

    2003-04-01

    Group A streptococci control expression of key virulence determinants via the two-component sensorregulator system CsrRCsrS. The membrane-bound sensor CsrS is thought to respond to previously unknown environmental signal(s) by controlling phosphorylation of its cognate regulator component CsrR. Phosphorylation of CsrR increases its affinity for binding to the promoter regions of Csr-regulated genes to repress transcription. Here we show that environmental Mg(2+) concentration is a potent and specific stimulus for CsrRCsrS-mediated regulation. We studied the effect of divalent cations on expression of the Csr-regulated hyaluronic acid capsule genes (hasABC) by measuring chloramphenicol acetyltransferase (CAT) activity in a reporter strain of group A Streptococcus carrying a has operon promoter-cat fusion. Addition of Mg(2+), but not of Ca(2+), Mn(2+), or Zn(2+), repressed capsule gene expression by up to 80% in a dose-dependent fashion. The decrease in capsule gene transcription was associated with a marked reduction in cell-associated capsular polysaccharide. RNA hybridization analysis demonstrated reduced expression of the Csr-regulated hasABC operon, streptokinase (ska), and streptolysin S (sagA) during growth in the presence of 15 mM Mg(2+) for the wild-type strain 003CAT but not for an isogenic csrS mutant. We propose that Mg(2+) binds to CsrS to induce phosphorylation of CsrR and subsequent repression of virulence gene expression. The low concentration of Mg(2+) in extracellular body fluids predicts that the CsrRCsrS system is maintained in the inactive state during infection, thereby allowing maximal expression of critical virulence determinants in the human host. PMID:12646707

  5. Regulation of arsenite oxidation by the phosphate two-component system PhoBR in Halomonas sp. HAL1.

    Science.gov (United States)

    Chen, Fang; Cao, Yajing; Wei, Sha; Li, Yanzhi; Li, Xiangyang; Wang, Qian; Wang, Gejiao

    2015-01-01

    Previously, the expression of arsenite [As(III)] oxidase genes aioBA was reported to be regulated by a three-component regulatory system, AioXSR, in a number of As(III)-oxidizing bacterial strains. However, the regulation mechanism is still unknown when aioXSR genes are absent in some As(III)-oxidizing bacterial genomes, such as in Halomonas sp. HAL1. In this study, transposon mutagenesis and gene knock-out mutation were performed, and two mutants, HAL1-phoR 931 and HAL1-▵phoB, were obtained in strain HAL1. The phoR and phoB constitute a two-component system which is responsible for phosphate (Pi) acquisition and assimilation. Both of the mutants showed negative As(III)-oxidation phenotypes in low Pi condition (0.1 mM) but not under normal Pi condition (1 mM). The phoBR complementation strain HAL1-▵phoB-C reversed the mutants' null phenotypes back to wild type status. Meanwhile, lacZ reporter fusions using pCM-lacZ showed that the expression of phoBR and aioBA were both induced by As(III) but were not induced in HAL1-phoR 931 and HAL1-▵phoB. Using 15 consensus Pho box sequences, a putative Pho box was found in the aioBA regulation region. PhoB was able to bind to the putative Pho box in vivo (bacterial one-hybrid detection) and in vitro (electrophoretic mobility gel shift assay), and an 18-bp binding sequence containing nine conserved bases were determined. This study provided the evidence that PhoBR regulates the expression of aioBA in Halomonas sp. HAL1 under low Pi condition. The new regulation model further implies the close metabolic connection between As and Pi. PMID:26441863

  6. Regulation of Arsenite Oxidation by the Phosphate Two-Component System PhoBR in Halomonas sp. HAL1

    Directory of Open Access Journals (Sweden)

    Fang eChen

    2015-09-01

    Full Text Available Previously, the expression of arsenite [As(III] oxidase genes aioBA was reported to be regulated by a three-component regulatory system, AioXSR, in a number of As(III-oxidizing bacterial strains. However, the regulation mechanism is still unknown when aioXSR genes are absent in some As(III-oxidizing bacterial genomes, such as in Halomonas sp. HAL1. In this study, transposon mutagenesis and gene knock-out mutation were performed, and two mutants, HAL1-phoR931 and HAL1-△phoB, were obtained in strain HAL1. The phoR and phoB constitute a two-component system which is responsible for phosphate (Pi acquisition and assimilation. Both of the mutants showed negative As(III-oxidation phenotypes in low Pi condition (0.1 mM but not under normal Pi condition (1 mM. The phoBR complementation strain HAL1-△phoB-C reversed the mutants’ null phenotypes back to wild type status. Meanwhile, lacZ reporter fusions using pCM-lacZ showed that the expression of phoBR and aioBA were both induced by As(III but were not induced in HAL1-phoR931 and HAL1-△phoB. Using 15 consensus Pho box sequences, a putative Pho box was found in the aioBA regulation region. PhoB was able to bind to the putative Pho box in vivo (bacterial one-hybrid detection and in vitro (electrophoretic mobility gel shift assay, and an 18-bp binding sequence containing nine conserved bases were determined. This study provided the evidence that PhoBR regulates the expression of aioBA in Halomonas sp. HAL1 under low Pi condition. The new regulation model further implies the close metabolic connection between As and Pi.

  7. Evolutionary history of the OmpR/IIIA family of signal transduction two component systems in Lactobacillaceae and Leuconostocaceae

    Directory of Open Access Journals (Sweden)

    González-Candelas Fernando

    2011-02-01

    Full Text Available Abstract Background Two component systems (TCS are signal transduction pathways which typically consist of a sensor histidine kinase (HK and a response regulator (RR. In this study, we have analyzed the evolution of TCS of the OmpR/IIIA family in Lactobacillaceae and Leuconostocaceae, two families belonging to the group of lactic acid bacteria (LAB. LAB colonize nutrient-rich environments such as foodstuffs, plant materials and the gastrointestinal tract of animals thus driving the study of this group of both basic and applied interest. Results The genomes of 19 strains belonging to 16 different species have been analyzed. The number of TCS encoded by the strains considered in this study varied between 4 in Lactobacillus helveticus and 17 in Lactobacillus casei. The OmpR/IIIA family was the most prevalent in Lactobacillaceae accounting for 71% of the TCS present in this group. The phylogenetic analysis shows that no new TCS of this family has recently evolved in these Lactobacillaceae by either lineage-specific gene expansion or domain shuffling. Furthermore, no clear evidence of non-orthologous replacements of either RR or HK partners has been obtained, thus indicating that coevolution of cognate RR and HKs has been prevalent in Lactobacillaceae. Conclusions The results obtained suggest that vertical inheritance of TCS present in the last common ancestor and lineage-specific gene losses appear as the main evolutionary forces involved in their evolution in Lactobacillaceae, although some HGT events cannot be ruled out. This would agree with the genomic analyses of Lactobacillales which show that gene losses have been a major trend in the evolution of this group.

  8. Association between polymorphisms in the csrRS two-component regulatory system and invasive group A streptococcal infection.

    Science.gov (United States)

    Lin, J-N; Chang, L-L; Lai, C-H; Lin, H-H; Chen, Y-H

    2014-05-01

    The csrRS two-component regulatory system is an important element in the pathogenesis of group A Streptococcus (GAS). The main goal of this study is to understand the association between csrRS polymorphisms and GAS infection. We sequenced the csrRS genes from 172 clinical isolates, including 81 invasive and 91 noninvasive isolates, and then employed phylogenetic analyses to determine the consequences of the csrRS polymorphisms. In total, 13 and 26 polymorphic loci were detected in the csrR and csrS genes, respectively. These polymorphisms constituted 14 csrR and 25 csrS alleles, producing two CsrR and seven CsrS variants, respectively. Three invasive isolates contained an indel in csrS, but no indel was identified in csrR. The frequency and distribution of polymorphisms in csrR and csrS was significantly different between the invasive and noninvasive infection isolates (p CsrR, only one noninvasive isolate was identified to have a V29I mutation. The amino acid substitutions in CsrS included S32P (0.6 %), E265G (0.6 %), E265K (0.6 %), I332V (1.7 %), and N498K (82.6 %). Isolates with an N498K single mutation were more likely to be associated with invasive infections (p csrR and csrS were under purifying selection. The fixation index suggested a moderate evolutionary differentiation of the csrR and csrS alleles between invasive and noninvasive isolates. The identification of these genetic differences within the csrRS loci will provide a better understanding of the pathogenesis of GAS. PMID:24158687

  9. A multi-step phosphorelay two-component system impacts on tolerance against dehydration stress in common wheat.

    Science.gov (United States)

    Gahlaut, Vijay; Mathur, Saloni; Dhariwal, Raman; Khurana, Jitendra P; Tyagi, Akhilesh K; Balyan, Harindra S; Gupta, Pushpendra K

    2014-12-01

    Wheat is an important staple crop, and its productivity is severely constrained by drought stress (DS). An understanding of the molecular basis of drought tolerance is necessary for genetic improvement of wheat for tolerance to DS. The two-component system (TCS) serves as a common sensor-regulator coupling mechanism implicated in the regulation of diverse biological processes (including response to DS) not only in prokaryotes, but also in higher plants. In the latter, TCS generally consists of two signalling elements, a histidine kinase (HK) and a response regulator (RR) associated with an intermediate element called histidine phosphotransferase (HPT). Keeping in view the possible utility of TCS in developing water use efficient (WUE) wheat cultivars, we identified and characterized 62 wheat genes encoding TCS elements in a silico study; these included 7 HKs, 45 RRs along with 10 HPTs. Twelve of the 62 genes showed relatively higher alterations in the expression under drought. The quantitative RT-PCR (qRT-PCR)-based expression analysis of these 12 TCS genes was carried out in wheat seedlings of a drought sensitive (HD2967) and a tolerant (Dharwar Dry) cultivar subjected to either dehydration stress or cytokinin treatment. The expression of these 12 genes under dehydration stress differed in sensitive and tolerant genotypes, even though for individual genes, both showed either up-regulation or down-regulation. In response to the treatment of cytokinin, the expression of type-A RR genes was higher in the tolerant genotype, relative to that in the sensitive genotype, the situation being reverse for the type-B RRs. These results have been discussed in the context of the role of TCS elements in drought tolerance in wheat. PMID:25228409

  10. Molecular evolution of the two-component system BvgAS involved in virulence regulation in Bordetella.

    Directory of Open Access Journals (Sweden)

    Julien Herrou

    Full Text Available The whooping cough agent Bordetella pertussis is closely related to Bordetella bronchiseptica, which is responsible for chronic respiratory infections in various mammals and is occasionally found in humans, and to Bordetella parapertussis, one lineage of which causes mild whooping cough in humans and the other ovine respiratory infections. All three species produce similar sets of virulence factors that are co-regulated by the two-component system BvgAS. We characterized the molecular diversity of BvgAS in Bordetella by sequencing the two genes from a large number of diverse isolates. The response regulator BvgA is virtually invariant, indicating strong functional constraints. In contrast, the multi-domain sensor kinase BvgS has evolved into two different types. The pertussis type is found in B. pertussis and in a lineage of essentially human-associated B. bronchiseptica, while the bronchiseptica type is associated with the majority of B. bronchiseptica and both ovine and human B. parapertussis. BvgS is monomorphic in B. pertussis, suggesting optimal adaptation or a recent population bottleneck. The degree of diversity of the bronchiseptica type BvgS is markedly different between domains, indicating distinct evolutionary pressures. Thus, absolute conservation of the putative solute-binding cavities of the two periplasmic Venus Fly Trap (VFT domains suggests that common signals are perceived in all three species, while the external surfaces of these domains vary more extensively. Co-evolution of the surfaces of the two VFT domains in each type and domain swapping experiments indicate that signal transduction in the periplasmic region may be type-specific. The two distinct evolutionary solutions for BvgS confirm that B. pertussis has emerged from a specific B. bronchiseptica lineage. The invariant regions of BvgS point to essential parts for its molecular mechanism, while the variable regions may indicate adaptations to different lifestyles. The

  11. Role of Salmonella enterica Serovar Typhimurium Two-Component System PreA/PreB in Modulating PmrA-Regulated Gene Transcription

    OpenAIRE

    Merighi, Massimo; Carroll-Portillo, Amanda; Septer, Alecia N.; Bhatiya, Aditi; Gunn, John S.

    2006-01-01

    The PmrA/PmrB two-component system encoded by the pmrCAB operon regulates the modification of Salmonella enterica serovar Typhimurium lipopolysaccharide leading to polymyxin B resistance. PmrA and PhoP are the only known activators of pmrCAB. A transposon mutagenesis screen for additional regulators of a pmrC::MudJ fusion led to the identification of a two-component system, termed PreA/PreB (pmrCAB regulators A and B), that controls the transcription of the pmrCAB operon in response to unknow...

  12. Origin and evolution of two-component debris discs and an application to the q$^1$ Eridani system

    CERN Document Server

    Schüppler, Christian; Löhne, Torsten; Booth, Mark; Kirchschlager, Florian; Wolf, Sebastian

    2016-01-01

    Many debris discs reveal a two-component structure, with an outer Kuiper-belt analogue and a warm inner component whose origin is still a matter of debate. One possibility is that warm emission stems from an "asteroid belt" closer in to the star. We consider a scenario in which a set of giant planets is formed in an initially extended planetesimal disc. These planets carve a broad gap around their orbits, splitting up the disc into the outer and the inner belts. After the gas dispersal, both belts undergo collisional evolution in a steady-state regime. This scenario is explored with detailed collisional simulations involving realistic physics to describe a long-term collisional depletion of the two-component disc. We find that the inner disc may be able to retain larger amounts of material at older ages than thought before on the basis of simplified analytic models. We show that the proposed scenario is consistent with a suite of thermal emission and scattered light observational data for a bright two-tempera...

  13. Phosphorelay of non-orthodox two component systems functions through a bi-molecular mechanism in vivo

    DEFF Research Database (Denmark)

    Jovanovic, Goran; Sheng, Xia; Ale, Angelique;

    2015-01-01

    functional relevance of the dimerization of a non-orthodox or hybrid histidine kinase along which the phosphorelay takes place has been a subject of debate. We use a combination of molecular and genetic approaches, coupled to mathematical and statistical modelling, to demonstrate that the different possible...... intra- and inter-molecular mechanisms of phosphotransfer are formally non-identifiable in Escherichia coli expressing the ArcB non-orthodox histidine kinase used in anoxic redox control. In order to resolve this issue we further analyse the mathematical model in order to identify discriminatory...... histidine kinase. This is the first detailed mechanistic analysis of the molecular processes involved in non-orthodox two-component signalling and our results suggest strongly that dimerization facilitates more discriminatory proof-reading of external signals, via these allosteric reactions, prior to them...

  14. The Novel Two-Component Regulatory System BfiSR Regulates Biofilm Development by Controlling the Small RNA rsmZ through CafA▿ †

    OpenAIRE

    Petrova, Olga E.; Sauer, Karin

    2010-01-01

    The formation of biofilms by the opportunistic pathogen Pseudomonas aeruginosa is a developmental process governed by a novel signal transduction system composed of three two-component regulatory systems (TCSs), BfiSR, BfmSR, and MifSR. Here, we show that BfiSR-dependent arrest of biofilm formation coincided with reduced expression of genes involved in virulence, posttranslational/transcriptional modification, and Rhl quorum sensing but increased expression of rhlAB and the small regulatory R...

  15. The Campylobacter jejuni RacRS two-component system activates the glutamate synthesis by directly upregulating γ-glutamyltranspeptidase (GGT)

    OpenAIRE

    van der Stel, Anne-Xander; van Mourik, Andries; Łaniewski, Paweł; van Putten, Jos P. M.; Jagusztyn-Krynicka, Elżbieta K.; Wosten, Marc

    2015-01-01

    The highly conserved enzyme γ-glutamyltranspeptidase (GGT) plays an important role in metabolism of glutathione and glutamine. Yet, the regulation of ggt transcription in prokaryotes is poorly understood. In the human pathogen Campylobacter jejuni, GGT is important as it contributes to persistent colonization of the gut. Here we show that the GGT activity in C. jejuni is dependent on a functional RacRS (reduced ability to colonize) two-component system. Electrophoretic mobility shift and luci...

  16. The impact of ColRS two-component system and TtgABC efflux pump on phenol tolerance of Pseudomonas putida becomes evident only in growing bacteria

    OpenAIRE

    Kivisaar Maia; Lilje Liisa; Ilves Heili; Putrinš Marta; Hõrak Rita

    2010-01-01

    Abstract Background We have recently found that Pseudomonas putida deficient in ColRS two-component system is sensitive to phenol and displays a serious defect on solid glucose medium where subpopulation of bacteria lyses. The latter phenotype is significantly enhanced by the presence of phenol in growth medium. Here, we focused on identification of factors affecting phenol tolerance of the colR-deficient P. putida. Results By using transposon mutagenesis approach we identified a set of pheno...

  17. A Two-Component Regulatory System, CsrR-CsrS, Represses Expression of Three Streptococcus pyogenes Virulence Factors, Hyaluronic Acid Capsule, Streptolysin S, and Pyrogenic Exotoxin B

    OpenAIRE

    Heath, Andrew; DiRita, Victor J.; Barg, Neil L.; Engleberg, N. Cary

    1999-01-01

    Certain Tn916 insertions in the chromosome of an M1-type, nonmucoid Streptococcus pyogenes isolate (MGAS166) were previously shown to result in stable mucoidy with increased expression of the capsular synthetic genes. The transposon insertions in these strains are directly upstream of an apparent operon encoding a two-component regulatory system, designated csrR-csrS. Compared with MGAS166, these mucoid mutants are more hemolytic and cause significantly more tissue damage in a murine model of...

  18. Crystal Structure of the Response Regulator 02 Receiver Domain, the Essential YycF Two-Component System of Streptococcus pneumoniae in both Complexed and Native States†

    OpenAIRE

    Bent, Colin J.; Isaacs, Neil W.; Mitchell, Timothy J.; Riboldi-Tunnicliffe, Alan

    2004-01-01

    A variety of bacterial cellular responses to environmental signals are mediated by two-component signal transduction systems comprising a membrane-associated histidine protein kinase and a cytoplasmic response regulator (RR), which interpret specific stimuli and produce a measured physiological response. In RR activation, transient phosphorylation of a highly conserved aspartic acid residue drives the conformation changes needed for full activation of the protein. Sequence homology reveals th...

  19. The two-component system CpxAR is essential for virulence in the phytopathogen bacteria Dickeya dadantii EC3937.

    Science.gov (United States)

    Bontemps-Gallo, Sébastien; Madec, Edwige; Lacroix, Jean-Marie

    2015-11-01

    The CpxAR two-component system is present in many Proteobacteria. It controls expression of genes required to maintain envelope integrity in response to environmental injury. Consequently, this two-component system was shown to be required for virulence of several zoo-pathogens, but it has never been investigated in phyto-pathogens. In this paper, we investigate the role of the CpxAR two-component system in vitro and in vivo in Dickeya dadantii, an enterobacterial phytopathogen that causes soft-rot disease in a large variety of plant species. cpxA null mutant displays a constitutively phosphorylated CpxR phenotype as shown by direct analysis of phosphorylation of CpxR by a Phos-Tag retardation gel approach. Virulence in plants is completely abolished in cpxA or cpxR mutants of D. dadantii. In planta, CpxAR is only activated at an early stage of the infection process as shown by Phos-Tag and gene fusion analyses. To our knowledge, this is the first time that the timing of CpxAR phosphorelay activation has been investigated during the infection process by direct monitoring of response regulator phosphorylation. PMID:25856505

  20. The development of a two-component force dynamometer and tool control system for dynamic machine tool research

    Science.gov (United States)

    Sutherland, I. A.

    1973-01-01

    The development is presented of a tooling system that makes a controlled sinusoidal oscillation simulating a dynamic chip removal condition. It also measures the machining forces in two mutually perpendicular directions without any cross sensitivity.

  1. Elliptic waves in two-component long-wave–short-wave resonance interaction system in one and two dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Khare, Avinash, E-mail: khare@iiserpune.ac.in [Raja Ramanna Fellow, Indian Institute of Science Education and Research, Pune 411021 (India); Kanna, T., E-mail: kanna_phy@bhc.edu.in [Post Graduate and Research Department of Physics, Bishop Heber College, Tiruchirapalli 620 017, Tamil Nadu (India); Tamilselvan, K., E-mail: tamsel786@gmail.com [Post Graduate and Research Department of Physics, Bishop Heber College, Tiruchirapalli 620 017, Tamil Nadu (India)

    2014-08-28

    We consider (2+1)- and (1+1)-dimensional long-wave–short-wave resonance interaction systems. We construct an extensive set of exact periodic solutions of these systems in terms of Lamé polynomials of order one and two. The periodic solutions are classified into three categories as similar, mixed, superposed elliptic solutions. We also discuss the hyperbolic solutions as limiting cases. - Highlights: • Jacobi elliptic solutions for (1+1)D and (2+1)D LSRI system in terms of Lamé polynomials order 1 and 2. • Three types of Jacobi elliptic solutions: similar, mixed, superposed solutions. • Identified special in-phase and out-of-phase periodic wave train solutions. • Demonstrated the appearance of various types of solitons in the hyperbolic limit. • Identified special solitary waves: bi-soliton and anti-dark soliton wave at the order 2.

  2. Elliptic waves in two-component long-wave–short-wave resonance interaction system in one and two dimensions

    International Nuclear Information System (INIS)

    We consider (2+1)- and (1+1)-dimensional long-wave–short-wave resonance interaction systems. We construct an extensive set of exact periodic solutions of these systems in terms of Lamé polynomials of order one and two. The periodic solutions are classified into three categories as similar, mixed, superposed elliptic solutions. We also discuss the hyperbolic solutions as limiting cases. - Highlights: • Jacobi elliptic solutions for (1+1)D and (2+1)D LSRI system in terms of Lamé polynomials order 1 and 2. • Three types of Jacobi elliptic solutions: similar, mixed, superposed solutions. • Identified special in-phase and out-of-phase periodic wave train solutions. • Demonstrated the appearance of various types of solitons in the hyperbolic limit. • Identified special solitary waves: bi-soliton and anti-dark soliton wave at the order 2

  3. Induction of RpoS Degradation by the Two-Component System Regulator RstA in Salmonella enterica▿

    OpenAIRE

    Cabeza, María L.; Aguirre, Andrés; Soncini, Fernando C.; Véscovi, Eleonora García

    2007-01-01

    Bacterial survival in diverse and changing environments relies on the accurate interplay between different regulatory pathways, which determine the design of an adequate adaptive response. The proper outcome depends on a precise gene expression profile generated from the finely tuned and concerted action of transcriptional factors of distinct regulatory hierarchies. Salmonella enterica serovar Typhimurium harbors multiple regulatory systems that are crucial for the bacterium to cope with hars...

  4. Regulation of Arsenite Oxidation by the Phosphate Two-Component System PhoBR in Halomonas sp. HAL1

    OpenAIRE

    Fang eChen; Yajing eCao; Sha eWei; Yanzhi eLi; Xiangyang eLi; Qian eWang; Gejiao eWang

    2015-01-01

    Previously, the expression of arsenite [As(III)] oxidase genes aioBA was reported to be regulated by a three-component regulatory system, AioXSR, in a number of As(III)-oxidizing bacterial strains. However, the regulation mechanism is still unknown when aioXSR genes are absent in some As(III)-oxidizing bacterial genomes, such as in Halomonas sp. HAL1. In this study, transposon mutagenesis and gene knock-out mutation were performed, and two mutants, HAL1-phoR931 and HAL1-△phoB, were obtained i...

  5. Regulation of arsenite oxidation by the phosphate two-component system PhoBR in Halomonas sp. HAL1

    OpenAIRE

    Chen, Fang; Cao, Yajing; Wei, Sha; Li, Yanzhi; Li, Xiangyang; Wang, Qian; Wang, Gejiao

    2015-01-01

    Previously, the expression of arsenite [As(III)] oxidase genes aioBA was reported to be regulated by a three-component regulatory system, AioXSR, in a number of As(III)-oxidizing bacterial strains. However, the regulation mechanism is still unknown when aioXSR genes are absent in some As(III)-oxidizing bacterial genomes, such as in Halomonas sp. HAL1. In this study, transposon mutagenesis and gene knock-out mutation were performed, and two mutants, HAL1-phoR 931 and HAL1-▵phoB, were obtained ...

  6. Polymyxin resistance of Pseudomonas aeruginosa phoQ mutants is dependent on additional two-component regulatory systems

    DEFF Research Database (Denmark)

    Gutu, Alina D; Sgambati, Nicole; Strasbourger, Pnina;

    2013-01-01

    systems, ColRS and CprRS. Deletion of the colRS genes, individually or in tandem, abrogated the polymyxin resistance of a ΔphoQ mutant, as did individual or tandem deletion of cprRS. Individual deletion of colR or colS in a ΔphoQ mutant also suppressed 4-amino-L-arabinose addition to lipid A, consistent...... with the known role of this modification in polymyxin resistance. Surprisingly, tandem deletion of colRS or cprRS in the ΔphoQ mutant or individual deletion of cprR or cprS failed to suppress 4-amino-L-arabinose addition to lipid A, indicating that this modification alone is not sufficient for Pho......PQ-mediated polymyxin resistance in P. aeruginosa. Episomal expression of colRS or cprRS in tandem or of cprR individually complemented the Pm resistance phenotype in the ΔphoQ mutant, while episomal expression of colR, colS, or cprS individually did not. Highly polymyxin-resistant phoQ mutants of P. aeruginosa...

  7. Expression of the RND-Type Efflux Pump AdeABC in Acinetobacter baumannii Is Regulated by the AdeRS Two-Component System

    OpenAIRE

    Marchand, Isabelle; Damier-Piolle, Laurence; Courvalin, Patrice; Lambert, Thierry

    2004-01-01

    The AdeABC pump of Acinetobacter baumannii BM4454, which confers resistance to various antibiotic classes including aminoglycosides, is composed of the AdeA, AdeB, and AdeC proteins; AdeB is a member of the RND superfamily. The adeA, adeB, and adeC genes are contiguous and adjacent to adeS and adeR, which are transcribed in the opposite direction and which specify proteins homologous to sensors and regulators of two-component systems, respectively (S. Magnet, P. Courvalin, and T. Lambert, Ant...

  8. Involvement of the HP0165-HP0166 Two-Component System in Expression of Some Acidic-pH-Upregulated Genes of Helicobacter pylori†

    OpenAIRE

    Wen, Yi; Feng, Jing; Scott, David R.; Marcus, Elizabeth A.; Sachs, George

    2006-01-01

    About 200 genes of the gastric pathogen Helicobacter pylori increase expression at medium pHs of 6.2, 5.5, and 4.5, an increase that is abolished or much reduced by the buffering action of urease. Genes up-regulated by a low pH include the two-component system HP0165-HP0166, suggesting a role in the regulation of some of the pH-sensitive genes. To identify targets of HP0165-HP0166, the promoter regions of genes up-regulated by a low pH were grouped based on sequence similarity. Probes for pro...

  9. Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS

    OpenAIRE

    Kevin Patel; Dasantila Golemi-Kotra

    2016-01-01

    The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the e...

  10. The Role of the Two-Component System BaeSR in Disposing Chemicals through Regulating Transporter Systems in Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Ming-Feng Lin

    Full Text Available Bacterial two-component regulatory systems (TCSs facilitate changes in gene expression in response to environmental stimuli. TCS BaeR regulons influence tigecycline susceptibility in Acinetobacter baumannii through positively regulating the pump genes adeA and adeB. In this study, we demonstrate that an additional two transport systems, AdeIJK and MacAB-TolC, are also regulated by BaeSR. In the wild type and clinical tigecycline-resistant A. baumannii strains, gene expression of AdeIJK and MacAB-TolC increased after tigecycline induction, implicating their importance to tigecycline resistance in addition to AdeABC. Phenotypic microarray results showed that A. baumannii is vulnerable to certain chemicals, especially tannic acid, after deleting baeR, which was confirmed using the spot assay. The wild-type strain of A. baumannii also exhibited 1.6-fold and 4.4-fold increase in gene expression of adeJ and macB in the medium with 100 μg/mL tannic acid, but the increase was fully inhibited by baeR deletion. An electrophoretic motility shift assay based on an interaction between His-BaeR and the adeA, adeI and macA promoter regions did not demonstrate direct binding. In conclusion, A. baumannii can use the TCS BaeSR in disposing chemicals, such as tannic acid and tigecycline, through regulating the efflux pumps.

  11. Searching for Potential Drug Targets in Two-component and Phosphorelay Signal-transduction Systems using Three-dimensional Cluster Analysis

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hui CAI; Qing ZHANG; Shuo-Yong SHI; Da-Fu DING

    2005-01-01

    Two-component and phosphorelay signal transduction systems are central components in the virulence and antimicrobial resistance responses of a number of bacterial and fungal pathogens; in some cases, these systems are essential for bacterial growth and viability. Herein, we analyze in detail the conserved surface residue clusters in the phosphotransferase domain of histidine kinases and the regulatory domain of response regulators by using complex structure-based three-dimensional cluster analysis. We also investigatethe protein-protein interactions that these residue clusters participate in. The Spo0B-SpoOF complex structure was used as the reference structure, and the multiple aligned sequences of phosphotransferases and response regulators were paired correspondingly. The results show that a contiguous conserved residue cluster is formed around the active site, which crosses the interface of histidine kinases and response regulators. The conserved residue clusters of phosphotransferase and the regulatory domains are directly involved in the functional implementation of two-component signal transduction systems and are good targets for the development of novel antimicrobial agents.

  12. A Two-Component Alkyne Metathesis Catalyst System with an Improved Substrate Scope and Functional Group Tolerance: Development and Applications to Natural Product Synthesis.

    Science.gov (United States)

    Schaubach, Sebastian; Gebauer, Konrad; Ungeheuer, Felix; Hoffmeister, Laura; Ilg, Marina K; Wirtz, Conny; Fürstner, Alois

    2016-06-13

    Although molybdenum alkylidyne complexes such as 1 endowed with triarylsilanolate ligands are excellent catalysts for alkyne metathesis, they can encounter limitations when (multiple) protic sites are present in a given substrate and/or when forcing conditions are necessary. In such cases, a catalyst formed in situ upon mixing of the trisamidomolybenum alkylidyne complex 3 and the readily available trisilanol derivatives 8 or 11 shows significantly better performance. This two-component system worked well for a series of model compounds comprising primary, secondary or phenolic -OH groups, as well as for a set of challenging (bis)propargylic substrates. Its remarkable efficiency is also evident from applications to the total syntheses of manshurolide, a highly strained sesquiterpene lactone with kinase inhibitory activity, and the structurally demanding immunosuppressive cyclodiyne ivorenolide A; in either case, the standard catalyst 1 largely failed to effect the critical macrocyclization, whereas the two-component system was fully operative. A study directed toward the quinolizidine alkaloid lythrancepine I features yet another instructive example, in that a triyne substrate was metathesized with the help of 3/11 such that two of the triple bonds participated in ring closure, while the third one passed uncompromised. As a spin-off of this project, a much improved ruthenium catalyst for the redox isomerization of propargyl alcohols to the corresponding enones was developed. PMID:27203803

  13. Systems level analysis of two-component signal transduction systems in Erwinia amylovora: Role in virulence, regulation of amylovoran biosynthesis and swarming motility

    Directory of Open Access Journals (Sweden)

    Sundin George W

    2009-05-01

    Full Text Available Abstract Background Two-component signal transduction systems (TCSTs, consisting of a histidine kinase (HK and a response regulator (RR, represent a major paradigm for signal transduction in prokaryotes. TCSTs play critical roles in sensing and responding to environmental conditions, and in bacterial pathogenesis. Most TCSTs in Erwinia amylovora have either not been identified or have not yet been studied. Results We used a systems approach to identify TCST and related signal transduction genes in the genome of E. amylovora. Comparative genomic analysis of TCSTs indicated that E. amylovora TCSTs were closely related to those of Erwinia tasmaniensis, a saprophytic enterobacterium isolated from apple flowers, and to other enterobacteria. Forty-six TCST genes in E. amylovora including 17 sensor kinases, three hybrid kinases, 20 DNA- or ligand-binding RRs, four RRs with enzymatic output domain (EAL-GGDEF proteins, and two kinases were characterized in this study. A systematic TCST gene-knockout experiment was conducted, generating a total of 59 single-, double-, and triple-mutants. Virulence assays revealed that five of these mutants were non-pathogenic on immature pear fruits. Results from phenotypic characterization and gene expression experiments indicated that several groups of TCST systems in E. amylovora control amylovoran biosynthesis, one of two major virulence factors in E. amylovora. Both negative and positive regulators of amylovoran biosynthesis were identified, indicating a complex network may control this important feature of pathogenesis. Positive (non-motile, EnvZ/OmpR, negative (hypermotile, GrrS/GrrA, and intermediate regulators for swarming motility in E. amylovora were also identified. Conclusion Our results demonstrated that TCSTs in E. amylovora played major roles in virulence on immature pear fruit and in regulating amylovoran biosynthesis and swarming motility. This suggested presence of regulatory networks governing

  14. The Two-Component System CprRS Senses Cationic Peptides and Triggers Adaptive Resistance in Pseudomonas aeruginosa Independently of ParRS

    DEFF Research Database (Denmark)

    Fernandez, Luca; Jenssen, Håvard; Bains, Manjeet;

    2012-01-01

    through ParRS. Here, we report the identification of a new two-component system, CprRS, which, upon exposure to a wide range of antimicrobial peptides, triggered the expression of the LPS modification operon. Thus, mutations in the cprRS operon blocked the induction of the arn operon in response to...... several antimicrobial peptides independently of ParRS but did not affect the response to low Mg2+. Distinct patterns of arn induction were identified. Thus, the responses to polymyxins were abrogated by either parR or cprR mutations, while responses to other peptides, including indolicidin, showed...... differential dependency on the CprRS and ParRS systems in a concentration-dependent manner. It was further demonstrated that, following exposure to inducing antimicrobial peptides, cprRS mutants did not become adaptively resistant to polymyxins as was observed for wild-type cells. Our microarray studies...

  15. The VirS/VirR two-component system regulates the anaerobic cytotoxicity, intestinal pathogenicity, and enterotoxemic lethality of Clostridium perfringens type C isolate CN3685.

    Science.gov (United States)

    Ma, Menglin; Vidal, Jorge; Saputo, Juliann; McClane, Bruce A; Uzal, Francisco

    2011-01-01

    Clostridium perfringens vegetative cells cause both histotoxic infections (e.g., gas gangrene) and diseases originating in the intestines (e.g., hemorrhagic necrotizing enteritis or lethal enterotoxemia). Despite their medical and veterinary importance, the molecular pathogenicity of C. perfringens vegetative cells causing diseases of intestinal origin remains poorly understood. However, C. perfringens beta toxin (CPB) was recently shown to be important when vegetative cells of C. perfringens type C strain CN3685 induce hemorrhagic necrotizing enteritis and lethal enterotoxemia. Additionally, the VirS/VirR two-component regulatory system was found to control CPB production by CN3685 vegetative cells during aerobic infection of cultured enterocyte-like Caco-2 cells. Using an isogenic virR null mutant, the current study now reports that the VirS/VirR system also regulates CN3685 cytotoxicity during infection of Caco-2 cells under anaerobic conditions, as found in the intestines. More importantly, the virR mutant lost the ability to cause hemorrhagic necrotic enteritis in rabbit small intestinal loops. Western blot analyses demonstrated that the VirS/VirR system mediates necrotizing enteritis, at least in part, by controlling in vivo CPB production. In addition, vegetative cells of the isogenic virR null mutant were, relative to wild-type vegetative cells, strongly attenuated in their lethality in a mouse enterotoxemia model. Collectively, these results identify the first regulator of in vivo pathogenicity for C. perfringens vegetative cells causing disease originating in the complex intestinal environment. Since VirS/VirR also mediates histotoxic infections, this two-component regulatory system now assumes a global role in regulating a spectrum of infections caused by C. perfringens vegetative cells. PMID:21264065

  16. The Eukaryotic-Like Ser/Thr Kinase PrkC Regulates the Essential WalRK Two-Component System in Bacillus subtilis.

    Science.gov (United States)

    Libby, Elizabeth A; Goss, Lindsie A; Dworkin, Jonathan

    2015-06-01

    Most bacteria contain both eukaryotic-like Ser/Thr kinases (eSTKs) and eukaryotic-like Ser/Thr phosphatases (eSTPs). Their role in bacterial physiology is not currently well understood in large part because the conditions where the eSTKs are active are generally not known. However, all sequenced Gram-positive bacteria have a highly conserved eSTK with extracellular PASTA repeats that bind cell wall derived muropeptides. Here, we report that in the Gram-positive bacterium Bacillus subtilis, the PASTA-containing eSTK PrkC and its cognate eSTP PrpC converge with the essential WalRK two-component system to regulate WalR regulon genes involved in cell wall metabolism. By continuously monitoring gene expression throughout growth, we consistently find a large PrkC-dependent effect on expression of several different WalR regulon genes in early stationary phase, including both those that are activated by WalR (yocH) as well as those that are repressed (iseA, pdaC). We demonstrate that PrkC phosphorylates WalR in vitro and in vivo on a single Thr residue located in the receiver domain. Although the phosphorylated region of the receiver domain is highly conserved among several B. subtilis response regulators, PrkC displays specificity for WalR in vitro. Consistently, strains expressing a nonphosphorylatable WalR point mutant strongly reduce both PrkC dependent activation and repression of yocH, iseA, and pdaC. This suggests a model where the eSTK PrkC regulates the essential WalRK two-component signaling system by direct phosphorylation of WalR Thr101, resulting in the regulation of WalR regulon genes involved in cell wall metabolism in stationary phase. As both the eSTK PrkC and the essential WalRK two-component system are highly conserved in Gram-positive bacteria, these results may be applicable to further understanding the role of eSTKs in Gram-positive physiology and cell wall metabolism. PMID:26102633

  17. The Eukaryotic-Like Ser/Thr Kinase PrkC Regulates the Essential WalRK Two-Component System in Bacillus subtilis.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Libby

    2015-06-01

    Full Text Available Most bacteria contain both eukaryotic-like Ser/Thr kinases (eSTKs and eukaryotic-like Ser/Thr phosphatases (eSTPs. Their role in bacterial physiology is not currently well understood in large part because the conditions where the eSTKs are active are generally not known. However, all sequenced Gram-positive bacteria have a highly conserved eSTK with extracellular PASTA repeats that bind cell wall derived muropeptides. Here, we report that in the Gram-positive bacterium Bacillus subtilis, the PASTA-containing eSTK PrkC and its cognate eSTP PrpC converge with the essential WalRK two-component system to regulate WalR regulon genes involved in cell wall metabolism. By continuously monitoring gene expression throughout growth, we consistently find a large PrkC-dependent effect on expression of several different WalR regulon genes in early stationary phase, including both those that are activated by WalR (yocH as well as those that are repressed (iseA, pdaC. We demonstrate that PrkC phosphorylates WalR in vitro and in vivo on a single Thr residue located in the receiver domain. Although the phosphorylated region of the receiver domain is highly conserved among several B. subtilis response regulators, PrkC displays specificity for WalR in vitro. Consistently, strains expressing a nonphosphorylatable WalR point mutant strongly reduce both PrkC dependent activation and repression of yocH, iseA, and pdaC. This suggests a model where the eSTK PrkC regulates the essential WalRK two-component signaling system by direct phosphorylation of WalR Thr101, resulting in the regulation of WalR regulon genes involved in cell wall metabolism in stationary phase. As both the eSTK PrkC and the essential WalRK two-component system are highly conserved in Gram-positive bacteria, these results may be applicable to further understanding the role of eSTKs in Gram-positive physiology and cell wall metabolism.

  18. Structural features of the two-component system LisR/LisK suggests multiple responses for the adaptation and survival of Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Nelson Enrique Arenas Suarez

    2013-08-01

    Full Text Available Here, we characterized the structure of the two-component regulatory system, LisR/LisK, in Listeria monocytogenes. To predict the structure of both proteins and the relationship between them, we employed several bioinformatic tools and databases. Based on our results, LisK protein is embedded in the cell membrane and its modular composition (HAMP, histidine kinase and ATPase domains is associated with its autophosphorylation (His-266. A stimulus-response likely determines the sequential signal propagation from the bacterial cell surface to its cytoplasmic components. According to our results, LisR is a cytoplasmic protein with a receptor domain (homologous to CheY that comprises a phosphoacceptor residue (Asp-52 and a DNA-binding domain, which may allow the transmission of a specific transcriptional response. LisR/LisK has been experimentally characterized both biochemically andfunctionally in other Bacilli pathophysiology; our structure-function approach may facilitate the design of suitable inhibitors.

  19. Expression of the RND-type efflux pump AdeABC in Acinetobacter baumannii is regulated by the AdeRS two-component system.

    Science.gov (United States)

    Marchand, Isabelle; Damier-Piolle, Laurence; Courvalin, Patrice; Lambert, Thierry

    2004-09-01

    The AdeABC pump of Acinetobacter baumannii BM4454, which confers resistance to various antibiotic classes including aminoglycosides, is composed of the AdeA, AdeB, and AdeC proteins; AdeB is a member of the RND superfamily. The adeA, adeB, and adeC genes are contiguous and adjacent to adeS and adeR, which are transcribed in the opposite direction and which specify proteins homologous to sensors and regulators of two-component systems, respectively (S. Magnet, P. Courvalin, and T. Lambert, Antimicrob. Agents Chemother. 45:3375-3380, 2001). Analysis by Northern hybridization indicated that the three genes were cotranscribed, although mRNAs corresponding to adeAB and adeC were also present. Cotranscription of the two regulatory genes was demonstrated by reverse transcription-PCR. Inactivation of adeS led to aminoglycoside susceptibility. Transcripts corresponding to adeAB were not detected in susceptible A. baumannii CIP 70-10 but were present in spontaneous gentamicin-resistant mutants obtained in vitro. Analysis of these mutants revealed the substitutions Thr153-->Met in AdeS downstream from the putative His-149 site of autophosphorylation, which is presumably responsible for the loss of phosphorylase activity by the sensor, and Pro116-->Leu in AdeR at the first residue of the alpha(5) helix of the receiver domain, which is involved in interactions that control the output domain of response regulators. These mutations led to constitutive expression of the pump and, thus, to antibiotic resistance. These data indicate that the AdeABC pump is cryptic in wild A. baumannii due to stringent control by the AdeRS two-component system. PMID:15328088

  20. Role of Salmonella enterica serovar Typhimurium two-component system PreA/PreB in modulating PmrA-regulated gene transcription.

    Science.gov (United States)

    Merighi, Massimo; Carroll-Portillo, Amanda; Septer, Alecia N; Bhatiya, Aditi; Gunn, John S

    2006-01-01

    The PmrA/PmrB two-component system encoded by the pmrCAB operon regulates the modification of Salmonella enterica serovar Typhimurium lipopolysaccharide leading to polymyxin B resistance. PmrA and PhoP are the only known activators of pmrCAB. A transposon mutagenesis screen for additional regulators of a pmrC::MudJ fusion led to the identification of a two-component system, termed PreA/PreB (pmrCAB regulators A and B), that controls the transcription of the pmrCAB operon in response to unknown signals. The initial observations indicated that insertions in, or a deletion of, the preB sensor, but not the preA response regulator, caused upregulation of pmrCAB. Interestingly, the expression of pmrCAB was not upregulated in a preAB mutant grown in LB broth, implicating PreA in the increased expression of pmrCAB in the preB strain. This was confirmed by overexpression of preA(+) in preAB or preB backgrounds, which resulted in significant upregulation or further upregulation of pmrCAB. No such effect was observed in any tested preB(+) backgrounds. Additionally, an ectopic construct expressing a preA[D51A] allele also failed to upregulate pmrC in any of the pre backgrounds tested, which implies that there is a need for phosphorylation in the activation of the target genes. The observed upregulation of pmrCAB occurred independently of the response regulators PmrA and PhoP. Although a preB mutation led to increased transcription of pmrCAB, this did not result in a measurable effect on polymyxin B resistance. Our genetic data support a model of regulation whereby, in response to unknown signals, the PreB sensor activates PreA, which in turn indirectly upregulates pmrCAB transcription. PMID:16352830

  1. The Hybrid Histidine Kinase LadS Forms a Multicomponent Signal Transduction System with the GacS/GacA Two-Component System in Pseudomonas aeruginosa.

    Science.gov (United States)

    Chambonnier, Gaël; Roux, Lorène; Redelberger, David; Fadel, Firas; Filloux, Alain; Sivaneson, Melissa; de Bentzmann, Sophie; Bordi, Christophe

    2016-05-01

    In response to environmental changes, Pseudomonas aeruginosa is able to switch from a planktonic (free swimming) to a sessile (biofilm) lifestyle. The two-component system (TCS) GacS/GacA activates the production of two small non-coding RNAs, RsmY and RsmZ, but four histidine kinases (HKs), RetS, GacS, LadS and PA1611, are instrumental in this process. RetS hybrid HK blocks GacS unorthodox HK autophosphorylation through the formation of a heterodimer. PA1611 hybrid HK, which is structurally related to GacS, interacts with RetS in P. aeruginosa in a very similar manner to GacS. LadS hybrid HK phenotypically antagonizes the function of RetS by a mechanism that has never been investigated. The four sensors are found in most Pseudomonas species but their characteristics and mode of signaling may differ from one species to another. Here, we demonstrated in P. aeruginosa that LadS controls both rsmY and rsmZ gene expression and that this regulation occurs through the GacS/GacA TCS. We additionally evidenced that in contrast to RetS, LadS signals through GacS/GacA without forming heterodimers, either with GacS or with RetS. Instead, we demonstrated that LadS is involved in a genuine phosphorelay, which requires both transmitter and receiver LadS domains. LadS signaling ultimately requires the alternative histidine-phosphotransfer domain of GacS, which is here used as an Hpt relay by the hybrid kinase. LadS HK thus forms, with the GacS/GacA TCS, a multicomponent signal transduction system with an original phosphorelay cascade, i.e. H1LadS→D1LadS→H2GacS→D2GacA. This highlights an original strategy in which a unique output, i.e. the modulation of sRNA levels, is controlled by a complex multi-sensing network to fine-tune an adapted biofilm and virulence response. PMID:27176226

  2. Two-component Dirac equation

    OpenAIRE

    Luo, Da-Wei; Pyshkin, P. V.; Yu, Ting; Lin, Hai-Qing; You, J. Q.; Wu, Lian-Ao

    2016-01-01

    We provide an alternative approach to relativistic dynamics based on the Feshbach projection technique. Instead of directly studying the Dirac equation, we derive a two-component equation for the upper spinor. This approach allows one to investigate the underlying physics in a different perspective. For particles with small mass such as the neutrino, the leading order equation has a Hermitian effective Hamiltonian, implying there is no leakage between the upper and lower spinors. In the weak ...

  3. Identification of genes for small non-coding RNAs that belong to the regulon of the two-component regulatory system CiaRH in Streptococcus

    Directory of Open Access Journals (Sweden)

    Hakenbeck Regine

    2010-11-01

    Full Text Available Abstract Background Post-transcriptional regulation by small RNAs (sRNAs in bacteria is now recognized as a wide-spread regulatory mechanism modulating a variety of physiological responses including virulence. In Streptococcus pneumoniae, an important human pathogen, the first sRNAs to be described were found in the regulon of the CiaRH two-component regulatory system. Five of these sRNAs were detected and designated csRNAs for cia-dependent small RNAs. CiaRH pleiotropically affects β-lactam resistance, autolysis, virulence, and competence development by yet to be defined molecular mechanisms. Since CiaRH is highly conserved among streptococci, it is of interest to determine if csRNAs are also included in the CiaRH regulon in this group of organisms consisting of commensal as well as pathogenic species. Knowledge on the participation of csRNAs in CiaRH-dependent regulatory events will be the key to define the physiological role of this important control system. Results Genes for csRNAs were predicted in streptococcal genomes and data base entries other than S. pneumoniae by searching for CiaR-activated promoters located in intergenic regions that are followed by a transcriptional terminator. 61 different candidate genes were obtained specifying csRNAs ranging in size from 51 to 202 nt. Comparing these genes among each other revealed 40 different csRNA types. All streptococcal genomes harbored csRNA genes, their numbers varying between two and six. To validate these predictions, S. mitis, S. oralis, and S. sanguinis were subjected to csRNA-specific northern blot analysis. In addition, a csRNA gene from S. thermophilus plasmid pST0 introduced into S. pneumoniae was also tested. Each of the csRNAs was detected on these blots and showed the anticipated sizes. Thus, the method applied here is able to predict csRNAs with high precision. Conclusions The results of this study strongly suggest that genes for small non-coding RNAs, csRNAs, are part of

  4. The Pseudomonas aeruginosa CreBC two-component system plays a major role in the response to β-lactams, fitness, biofilm growth, and global regulation.

    Science.gov (United States)

    Zamorano, Laura; Moyà, Bartolomé; Juan, Carlos; Mulet, Xavier; Blázquez, Jesús; Oliver, Antonio

    2014-09-01

    Pseudomonas aeruginosa is a ubiquitous versatile environmental microorganism with a remarkable ability to grow under diverse environmental conditions. Moreover, P. aeruginosa is responsible for life-threatening infections in immunocompromised and cystic fibrosis patients, as the extraordinary capacity of this pathogen to develop antimicrobial resistance dramatically limits our therapeutic arsenal. Its large genome carries an outstanding number of genes belonging to regulatory systems, including multiple two-component sensor-regulator systems that modulate the response to the different environmental stimuli. Here, we show that one of two systems, designated CreBC (carbon source responsive) and BlrAB (β-lactam resistance), might be of particular relevance. We first identified the stimuli triggering the activation of the CreBC system, which specifically responds to penicillin-binding protein 4 (PBP4) inhibition by certain β-lactam antibiotics. Second, through an analysis of a large comprehensive collection of mutants, we demonstrate an intricate interconnection between the CreBC system, the peptidoglycan recycling pathway, and the expression of the concerning chromosomal β-lactamase AmpC. Third, we show that the CreBC system, and particularly its effector inner membrane protein CreD, plays a major role in bacterial fitness and biofilm development, especially in the presence of subinhibitory concentrations of β-lactams. Finally, global transcriptomics reveals broad regulatory functions of CreBC in basic physiological aspects, particularly anaerobic respiration, in both the presence and absence of antibiotics. Therefore, the CreBC system is envisaged as a potentially interesting target for improving the efficacy of β-lactams against P. aeruginosa infections. PMID:24936599

  5. Two overlapping two-component systems in Xanthomonas oryzae pv. oryzae contribute to full fitness in rice by regulating virulence factors expression.

    Science.gov (United States)

    Zheng, Dehong; Yao, Xiaoyan; Duan, Meng; Luo, Yufeng; Liu, Biao; Qi, Pengyuan; Sun, Ming; Ruan, Lifang

    2016-01-01

    Two-component signal transduction systems (TCSs) are widely used by bacteria to adapt to the environment. In the present study, StoS (stress tolerance-related oxygen sensor) and SreKRS (salt response kinase, regulator, and sensor) were found to positively regulate extracellular polysaccharide (EPS) production and swarming in the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). Surprisingly, the absence of stoS or sreKRS did not attenuate virulence. To better understand the intrinsic functions of StoS and SreKRS, quantitative proteomics isobaric tags for relative and absolute quantitation (iTRAQ) was employed. Consistent with stoS and sreK mutants exhibiting a similar phenotype, the signalling circuits of StoS and SreKRS overlapped. Carbohydrate metabolism proteins and chemotaxis proteins, which could be responsible for EPS and swarming regulation, respectively, were reprogrammed in stoS and sreK mutants. Moreover, StoS and SreKRS demonstrated moderate expression of the major virulence factor, hypersensitive response and pathogenicity (Hrp) proteins through the HrpG-HrpX circuit. Most importantly, Xoo equipped with StoS and SreKRS outcompetes strains without StoS or SreKRS in co-infected rice and grows outside the host. Therefore, we propose that StoS and SreKRS adopt a novel strategy involving the moderation of Hrp protein expression and the promotion of EPS and motility to adapt to the environment. PMID:26957113

  6. Expression of the genes encoding the CasK/R two-component system and the DesA desaturase during Bacillus cereus cold adaptation.

    Science.gov (United States)

    Diomandé, Sara Esther; Doublet, Bénédicte; Vasaï, Florian; Guinebretière, Marie-Hélène; Broussolle, Véronique; Brillard, Julien

    2016-08-01

    Two-component systems (TCS) allow a cell to elaborate a variety of adaptive responses to environment changes. The recently discovered CasK/R TCS plays a role in the optimal unsaturation of fatty acids necessary for cold adaptation of the foodborne-pathogen Bacillus cereus Here, we showed that the promoter activity of the operon encoding this TCS was repressed during growth at low temperature in the stationary phase in the parental strain when compared to the casK/R mutant, suggesting that CasR negatively regulates the activity of its own promoter in these conditions. The promoter activity of the desA gene encoding the Δ5 fatty acid desaturase, providing unsaturated fatty acids (UFAs) required for low temperature adaptation, was repressed in the casK/R mutant grown at 12°C versus 37°C. This result suggests that CasK/R activates desA expression during B. cereus growth at low temperature, allowing an optimal unsaturation of the fatty acids. In contrast, desA expression was repressed during the lag phase at low temperature in presence of UFAs, in a CasK/R-independent manner. Our findings confirm that the involvement of this major TCS in B. cereus cold adaptation is linked to the upregulation of a fatty acid desaturase. PMID:27435329

  7. The Campylobacter jejuni RacRS two-component system activates the glutamate synthesis by directly upregulating γ-glutamyltranspeptidase (GGT

    Directory of Open Access Journals (Sweden)

    Anne-Xander evan der Stel

    2015-06-01

    Full Text Available The highly conserved enzyme γ-glutamyltranspeptidase (GGT plays an important role in metabolism of glutathione and glutamine. Yet, the regulation of ggt transcription in prokaryotes is poorly understood. In the human pathogen Campylobacter jejuni, GGT is important as it contributes to persistent colonization of the gut. Here we show that the GGT activity in C. jejuni is dependent on a functional RacRS (reduced ability to colonize two-component system. Electrophoretic mobility shift and luciferase reporter assays indicate that the response regulator RacR binds to a promoter region ~80 bp upstream of the ggt transcriptional start site, which contains a recently identified RacR DNA binding consensus sequence. RacR needs to be phosphorylated to activate the transcription of the ggt gene, which is the case under low oxygen conditions in presence of alternative electron acceptors. A functional GGT and RacR are needed to allow C. jejuni to grow optimally on glutamine as sole carbon source under RacR inducing conditions. However, when additional carbon sources are present C. jejuni is capable of utilizing glutamine independently of GGT. RacR is the first prokaryotic transcription factor known to directly upregulate both the cytoplasmic (glutamine-2-oxoglutarate aminotransferase (GOGAT as well as the periplasmic (GGT production of glutamate.

  8. Regulation of natural competence by the orphan two-component system sensor kinase ChiS involves a non-canonical transmembrane regulator in Vibrio cholerae.

    Science.gov (United States)

    Yamamoto, Shouji; Mitobe, Jiro; Ishikawa, Takahiko; Wai, Sun Nyunt; Ohnishi, Makoto; Watanabe, Haruo; Izumiya, Hidemasa

    2014-01-01

    In Vibrio cholerae, 41 chitin-inducible genes, including the genes involved in natural competence for DNA uptake, are governed by the orphan two-component system (TCS) sensor kinase ChiS. However, the mechanism by which ChiS controls the expression of these genes is currently unknown. Here, we report the involvement of a novel transcription factor termed 'TfoS' in this process. TfoS is a transmembrane protein that contains a large periplasmic domain and a cytoplasmic AraC-type DNA-binding domain, but lacks TCS signature domains. Inactivation of tfoS abolished natural competence as well as transcription of the tfoR gene encoding a chitin-induced small RNA essential for competence gene expression. A TfoS fragment containing the DNA-binding domain specifically bound to and activated transcription from the tfoR promoter. Intracellular TfoS levels were unaffected by disruption of chiS and coexpression of TfoS and ChiS in Escherichia coli recovered transcription of the chromosomally integrated tfoR::lacZ gene, suggesting that TfoS is post-translationally modulated by ChiS during transcriptional activation; however, this regulation persisted when the canonical phosphorelay residues of ChiS were mutated. The results presented here suggest that ChiS operates a chitin-induced non-canonical signal transduction cascade through TfoS, leading to transcriptional activation of tfoR. PMID:24236404

  9. The essential yhcSR two-component signal transduction system directly regulates the lac and opuCABCD operons of Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Meiying Yan

    Full Text Available Our previous studies suggested that the essential two-component signal transduction system, YhcSR, regulates the opuCABCD operon at the transcriptional level, and the Pspac-driven opuCABCD partially complements the lethal effects of yhcS antisense RNA expression in Staphylococcus aureus. However, the reason why yhcSR regulon is required for growth is still unclear. In this report, we present that the lac and opuC operons are directly transcriptionally regulated by YhcSR. Using real-time RT-PCR we showed that the down-regulation of yhcSR expression affected the transcription of lacA encoding galactose-6-phosphotase isomerase subunit LacA, and opuCA encoding a subunit of a glycine betaine/carnitine/choline ABC transporter. Promoter-lux reporter fusion studies further confirmed the transcriptional regulation of lac by YhcSR. Gel shift assays revealed that YhcR binds to the promoter regions of the lac and opuC operons. Moreover, the Pspac-driven lacABC expression in trans was able to partially complement the lethal effect of induced yhcS antisense RNA. Likewise, the Pspac-driven opuCABCD expression in trans complemented the growth defect of S. aureus in a high osmotic strength medium during the depletion of YhcSR. Taken together, the above data indicate that the yhcSR system directly regulates the expression of lac and opuC operons, which, in turn, may be partially associated with the essentiality of yhcSR in S. aureus. These results provide a new insight into the biological functions of the yhcSR, a global regulator.

  10. Regulation of hrp genes and type III protein secretion in Erwinia amylovora by HrpX/HrpY, a novel two-component system, and HrpS.

    Science.gov (United States)

    Wei, Z; Kim, J F; Beer, S V

    2000-11-01

    Two novel regulatory components, hrpX and hrpY, of the hrp system of Erwinia amylovora were identified. The hrpXY operon is expressed in rich media, but its transcription is increased threefold by low pH, nutrient, and temperature levels--conditions that mimic the plant apoplast. hrpXY is autoregulated and directs the expression of hrpL; hrpL, in turn, activates transcription of other loci in the hrp gene cluster (Z.-M. Wei and S. V. Beer, J. Bacteriol. 177:6201-6210, 1995). The deduced amino -acid sequences of hrpX and hrpY are similar to bacterial two-component regulators including VsrA/VsrD of Pseudomonas (Ralstonia) solanacearum, DegS/DegU of Bacillus subtilis, and UhpB/UhpA and NarX/NarP, NarL of Escherichia coli. The N-terminal signal-input domain of HrpX contains PAS domain repeats. hrpS, located downstream of hrpXY, encodes a protein with homology to WtsA (HrpS) of Erwinia (Pantoea) stewartii, HrpR and HrpS of Pseudomonas syringae, and other delta54-dependent, enhancer-binding proteins. Transcription of hrpS also is induced under conditions that mimic the plant apoplast. However, hrpS is not autoregulated, and its expression is not affected by hrpXY. When hrpS or hrpL were provided on multicopy plasmids, both hrpX and hrpY mutants recovered the ability to elicit the hypersensitive reaction in tobacco. This confirms that hrpS and hrpL are not epistatic to hrpXY. A model of the regulatory cascades leading to the induction of the E. amylovora type III system is proposed. PMID:11059492

  11. Potentiation of Aminoglycoside Activity in Pseudomonas aeruginosa by Targeting the AmgRS Envelope Stress-Responsive Two-Component System.

    Science.gov (United States)

    Poole, Keith; Gilmour, Christie; Farha, Maya A; Mullen, Erin; Lau, Calvin Ho-Fung; Brown, Eric D

    2016-06-01

    A screen for agents that potentiated the activity of paromomycin (PAR), a 4,5-linked aminoglycoside (AG), against wild-type Pseudomonas aeruginosa identified the RNA polymerase inhibitor rifampin (RIF). RIF potentiated additional 4,5-linked AGs, such as neomycin and ribostamycin, but not the clinically important 4,6-linked AGs amikacin and gentamicin. Potentiation was absent in a mutant lacking the AmgRS envelope stress response two-component system (TCS), which protects the organism from AG-generated membrane-damaging aberrant polypeptides and, thus, promotes AG resistance, an indication that RIF was acting via this TCS in potentiating 4,5-linked AG activity. Potentiation was also absent in a RIF-resistant RNA polymerase mutant, consistent with its potentiation of AG activity being dependent on RNA polymerase perturbation. PAR-inducible expression of the AmgRS-dependent genes htpX and yccA was reduced by RIF, suggesting that AG activation of this TCS was compromised by this agent. Still, RIF did not compromise the membrane-protective activity of AmgRS, an indication that it impacted some other function of this TCS. RIF potentiated the activities of 4,5-linked AGs against several AG-resistant clinical isolates, in two cases also potentiating the activity of the 4,6-linked AGs. These cases were, in one instance, explained by an observed AmgRS-dependent expression of the MexXY multidrug efflux system, which accommodates a range of AGs, with RIF targeting of AmgRS undermining mexXY expression and its promotion of resistance to 4,5- and 4,6-linked AGs. Given this link between AmgRS, MexXY expression, and pan-AG resistance in P. aeruginosa, RIF might be a useful adjuvant in the AG treatment of P. aeruginosa infections. PMID:27021319

  12. A two-component regulatory system, CsrR-CsrS, represses expression of three Streptococcus pyogenes virulence factors, hyaluronic acid capsule, streptolysin S, and pyrogenic exotoxin B.

    Science.gov (United States)

    Heath, A; DiRita, V J; Barg, N L; Engleberg, N C

    1999-10-01

    Certain Tn916 insertions in the chromosome of an M1-type, nonmucoid Streptococcus pyogenes isolate (MGAS166) were previously shown to result in stable mucoidy with increased expression of the capsular synthetic genes. The transposon insertions in these strains are directly upstream of an apparent operon encoding a two-component regulatory system, designated csrR-csrS. Compared with MGAS166, these mucoid mutants are more hemolytic and cause significantly more tissue damage in a murine model of skin infection. To extend these observations, we constructed an in-frame deletion in the gene encoding the response regulator, csrR, and we evaluated the expression of other known S. pyogenes virulence factors. We discovered that csrR mutants have enhanced transcription of sagA, a gene associated with streptolysin S (SLS) and speB, the gene encoding pyrogenic exotoxin B (SpeB). The mutants also express substantially higher SLS activity and SpeB antigen in late-exponential-phase cultures. There is no change in expression of emm, scpA, sic, or cpa (genes encoding other S. pyogenes virulence factors). CsrR- strains but not the wild-type parental strain produce necrotizing lesions in a mouse model of subcutaneous infection. A double mutant with deletions in both csrR and the capsular synthesis genes caused fewer and smaller necrotic skin lesions than the csrR mutants. However, this nonmucoid csrR strain was more likely than the wild type to yield necrotic lesions, suggesting that mucoidy contributes to virulence in this model of infection but that there are other csrR-regulated factors involved in the production of necrotic lesions. PMID:10496909

  13. Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS.

    Science.gov (United States)

    Patel, Kevin; Golemi-Kotra, Dasantila

    2015-01-01

    The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the expression of cidABC and lrgAB operons, the gene products of which are involved in programmed cell death and lysis. In vivo studies have demonstrated involvement of two overlapping regulatory networks in regulating the lrgAB operon, both depending on LytR. One regulatory network responds to glucose metabolism and the other responds to changes in the cell membrane potential. Herein, we show that LytS has autokinase activity and can catalyze a fast phosphotransfer reaction, with 50% of its phosphoryl group lost within 1 minute of incubation with LytR. LytS has also phosphatase activity. Notably, LytR undergoes phosphorylation by acetyl phosphate at a rate that is 2-fold faster than the phosphorylation by LytS. This observation is significant in lieu of the in vivo observations that regulation of the lrgAB operon is LytR-dependent in the presence of excess glucose in the medium. The latter condition does not lead to perturbation of the cell membrane potential but rather to the accumulation of acetate in the cell. Our study provides insights into the molecular basis for regulation of lrgAB in a LytR-dependent manner under conditions that do not involve sensing by LytS. PMID:27127614

  14. Peptidoglycan metabolism is controlled by the WalRK (YycFG) and PhoPR two-component systems in phosphate-limited Bacillus subtilis cells.

    Science.gov (United States)

    Bisicchia, Paola; Lioliou, Efthimia; Noone, David; Salzberg, Letal I; Botella, Eric; Hübner, Sebastian; Devine, Kevin M

    2010-02-01

    In Bacillus subtilis, the WalRK (YycFG) two-component system controls peptidoglycan metabolism in exponentially growing cells while PhoPR controls the response to phosphate limitation. Here we examine the roles of WalRK and PhoPR in peptidoglycan metabolism in phosphate-limited cells. We show that B. subtilis cells remain viable in a phosphate-limited state for an extended period and resume growth rapidly upon phosphate addition, even in the absence of a PhoPR-mediated response. Peptidoglycan synthesis occurs in phosphate-limited wild-type cells at approximately 27% the rate of exponentially growing cells, and at approximately 18% the rate of exponentially growing cells in the absence of PhoPR. In phosphate-limited cells, the WalRK regulon genes yocH, cwlO(yvcE), lytE and ydjM are expressed in a manner that is dependent on the WalR recognition sequence and deleting these genes individually reduces the rate of peptidoglycan synthesis. We show that ydjM expression can be activated by PhoP approximately P in vitro and that PhoP occupies its promoter in phosphate-limited cells. However, iseA(yoeB) expression cannot be repressed by PhoP approximately P in vitro, but can be repressed by non-phosphorylated WalR in vitro. Therefore, we conclude that peptidoglycan metabolism is controlled by both WalRK and PhoPR in phosphate-limited B. subtilis cells. PMID:20487291

  15. The two-component signal transduction system ArlRS regulates Staphylococcus epidermidis biofilm formation in an ica-dependent manner.

    Directory of Open Access Journals (Sweden)

    Yang Wu

    Full Text Available Due to its ability to form biofilms on medical devices, Staphylococcus epidermidis has emerged as a major pathogen of nosocomial infections. In this study, we investigated the role of the two-component signal transduction system ArlRS in regulating S. epidermidis biofilm formation. An ArlRS-deficient mutant, WW06, was constructed using S. epidermidis strain 1457 as a parental strain. Although the growth curve of WW06 was similar to that of SE1457, the mutant strain was unable to form biofilms in vitro. In a rabbit subcutaneous infection model, sterile disks made of polymeric materials were implanted subcutaneously followed with inoculation of WW06 or SE1457. The viable bacteria cells of WW06 recovered from biofilms on the embedded disks were much lower than that of SE1457. Complementation of arlRS genes expression from plasmid in WW06 restored biofilm-forming phenotype both in vivo and in vitro. WW06 maintained the ability to undergo initial attachment. Transcription levels of several genes involved in biofilm formation, including icaADBC, sigB, and sarA, were decreased in WW06, compared to SE1457; and icaR expression was increased in WW06, detected by real-time reverse-transcription PCR. The biofilm-forming phenotype was restored by overexpressing icaADBC in WW06 but not by overexpressing sigB, indicating that ArlRS regulates biofilm formation through the regulation of icaADBC. Gel shift assay showed that ArlR can bind to the promoter region of the ica operon. In conclusion, ArlRS regulates S. epidermidis biofilm formation in an ica-dependent manner, distinct from its role in S. aureus.

  16. Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

    Directory of Open Access Journals (Sweden)

    Zhen Zhang

    2013-03-01

    Full Text Available Blocking neurotransmission, botulinum neurotoxin is the most poisonous biological substance known to mankind. Despite its infamy as the scourge of the food industry, the neurotoxin is increasingly used as a pharmaceutical to treat an expanding range of muscle disorders. Whilst neurotoxin expression by the spore-forming bacterium Clostridium botulinum appears tightly regulated, to date only positive regulatory elements, such as the alternative sigma factor BotR, have been implicated in this control. The identification of negative regulators has proven to be elusive. Here, we show that the two-component signal transduction system CBO0787/CBO0786 negatively regulates botulinum neurotoxin expression. Single insertional inactivation of cbo0787 encoding a sensor histidine kinase, or of cbo0786 encoding a response regulator, resulted in significantly elevated neurotoxin gene expression levels and increased neurotoxin production. Recombinant CBO0786 regulator was shown to bind to the conserved -10 site of the core promoters of the ha and ntnh-botA operons, which encode the toxin structural and accessory proteins. Increasing concentration of CBO0786 inhibited BotR-directed transcription from the ha and ntnh-botA promoters, demonstrating direct transcriptional repression of the ha and ntnh-botA operons by CBO0786. Thus, we propose that CBO0786 represses neurotoxin gene expression by blocking BotR-directed transcription from the neurotoxin promoters. This is the first evidence of a negative regulator controlling botulinum neurotoxin production. Understanding the neurotoxin regulatory mechanisms is a major target of the food and pharmaceutical industries alike.

  17. Role of the two component signal transduction system CpxAR in conferring cefepime and chloramphenicol resistance in Klebsiella pneumoniae NTUH-K2044.

    Directory of Open Access Journals (Sweden)

    Vijaya Bharathi Srinivasan

    Full Text Available BACKGROUND: Klebsiella pneumoniae is a gram-negative, non-motile, facultative anaerobe belonging to the Enterobacteriaceae family of the γ-Proteobacteria class in the phylum Proteobacteria. Multidrug resistant K. pneumoniae have caused major therapeutic problems worldwide due to emergence of extended-spectrum β-lactamase producing strains. Two-component systems serve as a basic stimulus-response coupling mechanism to allow organisms to sense and respond to changes in many different environmental conditions including antibiotic stress. PRINCIPAL FINDINGS: In the present study, we investigated the role of an uncharacterized cpxAR operon in bacterial physiology and antimicrobial resistance by generating isogenic mutant (ΔcpxAR deficient in the CpxA/CpxR component derived from the hyper mucoidal K1 strain K. pneumoniae NTUH-K2044. The behaviour of ΔcpxAR was determined under hostile conditions, reproducing stresses encountered in the gastrointestinal environment and deletion resulted in higher sensitivity to bile, osmotic and acid stresses. The ΔcpxAR was more susceptible to β-lactams and chloramphenicol than the wild-type strain, and complementation restored the altered phenotypes. The relative change in expression of acrB, acrD, eefB efflux genes were decreased in cpxAR mutant as evidenced by qRT-PCR. Comparison of outer membrane protein profiles indicated a conspicuous difference in the knock out background. Gel shift assays demonstrated direct binding of CpxR(KP to promoter region of ompC(KP in a concentration dependent manner. CONCLUSIONS AND SIGNIFICANCE: The Cpx envelope stress response system is known to be activated by alterations in pH, membrane composition and misfolded proteins, and this systematic investigation reveals its direct involvement in conferring antimicrobial resistance against clinically significant antibiotics for the very first time. Overall results displayed in this report reflect the pleiotropic role of the Cpx

  18. The impact of ColRS two-component system and TtgABC efflux pump on phenol tolerance of Pseudomonas putida becomes evident only in growing bacteria

    Directory of Open Access Journals (Sweden)

    Kivisaar Maia

    2010-04-01

    Full Text Available Abstract Background We have recently found that Pseudomonas putida deficient in ColRS two-component system is sensitive to phenol and displays a serious defect on solid glucose medium where subpopulation of bacteria lyses. The latter phenotype is significantly enhanced by the presence of phenol in growth medium. Here, we focused on identification of factors affecting phenol tolerance of the colR-deficient P. putida. Results By using transposon mutagenesis approach we identified a set of phenol-tolerant derivatives of colR-deficient strain. Surprisingly, half of independent phenol tolerant clones possessed miniTn5 insertion in the ttgABC operon. However, though inactivation of TtgABC efflux pump significantly enhanced phenol tolerance, it did not affect phenol-enhanced autolysis of the colR mutant on glucose medium indicating that phenol- and glucose-caused stresses experienced by the colR-deficient P. putida are not coupled. Inactivation of TtgABC pump significantly increased the phenol tolerance of the wild-type P. putida as well. Comparison of phenol tolerance of growing versus starving bacteria revealed that both ColRS and TtgABC systems affect phenol tolerance only under growth conditions and not under starvation. Flow cytometry analysis showed that phenol strongly inhibited cell division and to some extent also caused cell membrane permeabilization to propidium iodide. Single cell analysis of populations of the ttgC- and colRttgC-deficient strains revealed that their membrane permeabilization by phenol resembles that of the wild-type and the colR mutant, respectively. However, cell division of P. putida with inactivated TtgABC pump seemed to be less sensitive to phenol than that of the parental strain. At the same time, cell division appeared to be more inhibited in the colR-mutant strain than in the wild-type P. putida. Conclusions ColRS signal system and TtgABC efflux pump are involved in the phenol tolerance of P. putida. However, as

  19. Transcriptional profiling of the two-component regulatory system VraSR in Staphylococcus aureus with low-level vancomycin resistance.

    Science.gov (United States)

    Chen, Hongbin; Xiong, Zhujia; Liu, Kuoyue; Li, Shuguang; Wang, Ruobing; Wang, Xiaojuan; Zhang, Yawei; Wang, Hui

    2016-05-01

    The objective of this study was to comprehensively identify the target genes regulated by the two-component regulatory system VraSR in Staphylococcus aureus and to clarify the role of VraSR in low-level vancomycin resistance. Expression of vraS was determined by real-time quantitative reverse transcriptase PCR (qRT-PCR). A clinical heterogeneous vancomycin-intermediate S. aureus (hVISA) strain B6D and a vancomycin-intermediate S. aureus (VISA) strain D7 that was induced from a meticillin-resistant S. aureus strain were selected to construct vraSR null mutants by allelic replacement. The vraSR-complemented strain B6D_c was also constructed by allelic replacement. Genes differentially expressed in the wild-type, vraSR null mutant and complemented strains were detected using RNA-Seq and were validated by qRT-PCR. Compared with vancomycin-susceptible S. aureus strains, expression of vraS was upregulated in all four isogenic hVISA strains. Vancomycin minimum inhibitory concentrations (MICs) in the vraSR null mutants B6D-ΔvraSR and D7-ΔvraSR were significantly lower than in the wild-type strains B6D and D7 and the complemented strain B6D_c. RNA-Seq and qRT-PCR data showed that expression of genes encoding FmtA protein, foldase protein PrsA, capsular polysaccharide biosynthesis glycosyltransferase, TcaA, a putative membrane protein, and six hypothetical proteins was down regulated in both vraSR-null mutants B6D-ΔvraSR and D7-ΔvraSR. Most of these differentially expressed proteins are involved in cell wall biosynthesis, which is associated with vancomycin resistance in S. aureus. In conclusion, VraSR plays an important role in S. aureus strains with low-level vancomycin resistance. PrsA, FmtA, glycosyltransferase and TcaA are regulated directly or indirectly by VraSR. PMID:27084050

  20. Ab initio two-component Ehrenfest dynamics

    International Nuclear Information System (INIS)

    We present an ab initio two-component Ehrenfest-based mixed quantum/classical molecular dynamics method to describe the effect of nuclear motion on the electron spin dynamics (and vice versa) in molecular systems. The two-component time-dependent non-collinear density functional theory is used for the propagation of spin-polarized electrons while the nuclei are treated classically. We use a three-time-step algorithm for the numerical integration of the coupled equations of motion, namely, the velocity Verlet for nuclear motion, the nuclear-position-dependent midpoint Fock update, and the modified midpoint and unitary transformation method for electronic propagation. As a test case, the method is applied to the dissociation of H2 and O2. In contrast to conventional Ehrenfest dynamics, this two-component approach provides a first principles description of the dynamics of non-collinear (e.g., spin-frustrated) magnetic materials, as well as the proper description of spin-state crossover, spin-rotation, and spin-flip dynamics by relaxing the constraint on spin configuration. This method also holds potential for applications to spin transport in molecular or even nanoscale magnetic devices

  1. 两部件串联维修系统解的定性分析%The Qualitative Analysis of a Solution of a Series Maintenance System with Two Components

    Institute of Scientific and Technical Information of China (English)

    郭卫华; 杨明增

    2003-01-01

    In this paper, firstly we study the series maintenance system with two components, obtain its exsistence and uniqueness of a dynamic state nonnegative solution by strongly continuous semigroups of operators theory. Then we prove that 0 is the eigenvalue of the system's host operators, and finally we study the eigenvector of the eigenvalue 0.

  2. Two component theory and electron magnetic moment

    NARCIS (Netherlands)

    Veltman, M.J.G.

    1998-01-01

    The two-component formulation of quantum electrodynamics is studied. The relation with the usual Dirac formulation is exhibited, and the Feynman rules for the two-component form of the theory are presented in terms of familiar objects. The transformation from the Dirac theory to the two-component th

  3. Derivative of plant phenolic compound inhibits the type III secretion system of Dickeya dadantii via HrpX/HrpY two-component signal transduction and Rsm systems.

    Science.gov (United States)

    Li, Yan; Hutchins, William; Wu, Xiaogang; Liang, Cuirong; Zhang, Chengfang; Yuan, Xiaochen; Khokhani, Devanshi; Chen, Xin; Che, Yizhou; Wang, Qi; Yang, Ching-Hong

    2015-02-01

    The type III secretion system (T3SS) is a major virulence factor in many Gram-negative bacterial pathogens and represents a particularly appealing target for antimicrobial agents. Previous studies have shown that the plant phenolic compound p-coumaric acid (PCA) plays a role in the inhibition of T3SS expression of the phytopathogen Dickeya dadantii 3937. This study screened a series of derivatives of plant phenolic compounds and identified that trans-4-hydroxycinnamohydroxamic acid (TS103) has an eight-fold higher inhibitory potency than PCA on the T3SS of D. dadantii. The effect of TS103 on regulatory components of the T3SS was further elucidated. Our results suggest that TS103 inhibits HrpY phosphorylation and leads to reduced levels of hrpS and hrpL transcripts. In addition, through a reduction in the RNA levels of the regulatory small RNA RsmB, TS103 also inhibits hrpL at the post-transcriptional level via the rsmB-RsmA regulatory pathway. Finally, TS103 inhibits hrpL transcription and mRNA stability, which leads to reduced expression of HrpL regulon genes, such as hrpA and hrpN. To our knowledge, this is the first inhibitor to affect the T3SS through both the transcriptional and post-transcriptional pathways in the soft-rot phytopathogen D. dadantii 3937. PMID:24986378

  4. Vancomycin susceptibility in methicillin-resistant Staphylococcus aureus is mediated by YycHI activation of the WalRK essential two-component regulatory system.

    Science.gov (United States)

    Cameron, David R; Jiang, Jhih-Hang; Kostoulias, Xenia; Foxwell, Daniel J; Peleg, Anton Y

    2016-01-01

    The treatment of infections caused by methicillin-resistant Staphylococcus aureus is complicated by the emergence of strains with intermediate-level resistance to vancomycin (termed VISA). We have characterised a molecular pathway involved in the in vivo evolution of VISA mediated by the regulatory proteins YycH and YycI. In contrast to their function in other bacterial species, we report a positive role for these auxiliary proteins in regulation of the two-component regulator WalRK. Transcriptional profiling of yycH and yycI deletion mutants revealed downregulation of the 'WalRK regulon' including cell wall hydrolase genes atlA and sle1, with functional autolysis assays supporting these data by showing an impaired autolytic phenotype for each deletion strain. Using bacterial-two hybrid assays, we showed that YycH and YycI interact, and that YycHI also interacts with the sensor kinase WalK, forming a ternary protein complex. Mutation to YycH or YycI associated with clinical VISA strains had a deleterious impact on the YycHI/WalK complex, suggesting that the interaction is important for the regulation of WalRK. Taken together, we have described a novel antibiotic resistance strategy for the human pathogen S. aureus, whereby YycHI mutations are selected for in vivo leading to reduced WalRK activation, impaired cell wall turnover and ultimately reduced vancomycin efficacy. PMID:27600558

  5. Two Component Signal Transduction in Desulfovibrio Species

    Energy Technology Data Exchange (ETDEWEB)

    Luning, Eric; Rajeev, Lara; Ray, Jayashree; Mukhopadhyay, Aindrila

    2010-05-17

    The environmentally relevant Desulfovibrio species are sulfate-reducing bacteria that are of interest in the bioremediation of heavy metal contaminated water. Among these, the genome of D. vulgaris Hildenborough encodes a large number of two component systems consisting of 72 putative response regulators (RR) and 64 putative histidinekinases (HK), the majority of which are uncharacterized. We classified the D. vulgaris Hildenborough RRs based on their output domains and compared the distribution of RRs in other sequenced Desulfovibrio species. We have successfully purified most RRs and several HKs as His-tagged proteins. We performed phospho-transfer experiments to verify relationships between cognate pairs of HK and RR, and we have also mapped a few non-cognate HK-RR pairs. Presented here are our discoveries from the Desulfovibrio RR categorization and results from the in vitro studies using purified His tagged D. vulgaris HKs and RRs.

  6. Two-component Duality and Strings

    OpenAIRE

    Freund, Peter G. O.

    2007-01-01

    A phenomenologically successful two-component hadronic duality picture led to Veneziano's amplitude, the fundamental first step to string theory. This picture is briefly recalled and its two components are identified as the open strings (mesons and baryons) and closed strings (Pomeron).

  7. An aromatic hydroxylation reaction catalyzed by a two-component FMN-dependent Monooxygenase. The ActVA-ActVB system from Streptomyces coelicolor.

    OpenAIRE

    Valton, Julien; Fontecave, Marc; Douki, Thierry; Kendrew, Steven G; Nivière, Vincent

    2006-01-01

    International audience The ActVA-ActVB system from Streptomyces coelicolor isatwo-component flavin-dependent monooxygenase that belongs to an emerging class of enzymes involved in various oxidation reactions in microorganisms. The ActVB component is a NADH:flavin oxidoreductase that provides a reduced FMN to the second component, ActVA the proper monooxygenase. In this work, we demonstrate that the ActVA-ActVB system catalyzes the aromatic monohydroxylation of dihydrokalafungin by molecula...

  8. The Pseudomonas aeruginosa CreBC Two-Component System Plays a Major Role in the Response to β-Lactams, Fitness, Biofilm Growth, and Global Regulation

    OpenAIRE

    Zamorano, Laura; Moyà, Bartolomé; Juan, Carlos; Mulet, Xavier; Blázquez, Jesús; Oliver, Antonio

    2014-01-01

    Pseudomonas aeruginosa is a ubiquitous versatile environmental microorganism with a remarkable ability to grow under diverse environmental conditions. Moreover, P. aeruginosa is responsible for life-threatening infections in immunocompromised and cystic fibrosis patients, as the extraordinary capacity of this pathogen to develop antimicrobial resistance dramatically limits our therapeutic arsenal. Its large genome carries an outstanding number of genes belonging to regulatory systems, includi...

  9. The Clostridium difficile cpr Locus Is Regulated by a Noncontiguous Two-Component System in Response to Type A and B Lantibiotics

    OpenAIRE

    Suárez, Jose M.; Edwards, Adrianne N.; McBride, Shonna M

    2013-01-01

    The intestinal pathogen Clostridium difficile is known to grow only within the intestines of mammals, yet little is known about how the bacterium subsists in this environment. In the intestine, C. difficile must contend with innate defenses within the host, such as cationic antimicrobial peptides (CAMPs) produced by the host and the indigenous microbiota. In this study, we investigated the mechanism of activation and regulation of the CprABC transporter system, which provides resistance to mu...

  10. The BatR/BatS two-component regulatory system controls the adaptive response of Bartonella henselae during human endothelial cell infection

    OpenAIRE

    Quebatte, Maxime; Dehio, Michaela; Tropel, David; Basler, Andrea; Toller, Isabella; Raddatz, Guenter; Engel, Philipp; Huser, Sonja; Schein, Hermine; Lindroos, Hillevi L.; Andersson, Siv G. E.; Dehio, Christoph

    2010-01-01

    Here, we report the first comprehensive study of Bartonella henselae gene expression during infection of human endothelial cells. Expression of the main cluster of upregulated genes, comprising the VirB type IV secretion system and its secreted protein substrates, is shown to be under the positive control of the transcriptional regulator BatR. We demonstrate binding of BatR to the promoters of the virB operon and a substrate-encoding gene and provide biochemical evidence that BatR and BatS co...

  11. Normal solution and transport coefficients to the Enskog-Landau kinetic equation for a two-component system of charged hard spheres The Chapman-Enskog method

    CERN Document Server

    Kobryn, A E; Tokarchuk, M V

    1999-01-01

    An Enskog-Landau kinetic equation for a many-component system of charged hard spheres is proposed. It has been obtained from the Liouville equation with modified boundary conditions by the method of nonequilibrium statistical operator. On the basis of this equation the normal solutions and transport coefficients such as bulk kappa and shear eta viscosities, thermal conductivity lambda, mutual diffusion D^{\\alpha\\beta} and thermal diffusion D_T^\\alpha have been obtained for a binary mixture in the first approximation using the Chapman-Enskog method. Numerical calculations of all transport coefficients for mixtures Ar-Kr, Ar-Xe, Kr-Xe with different concentrations of compounds have been evaluated for the cases of absence and presence of long-range Coulomb interactions. The results are compared with those obtained from other theories and experiment.

  12. The IRF5–TNPO3 association with systemic lupus erythematosus has two components that other autoimmune disorders variably share

    Science.gov (United States)

    Kottyan, Leah C.; Zoller, Erin E.; Bene, Jessica; Lu, Xiaoming; Kelly, Jennifer A.; Rupert, Andrew M.; Lessard, Christopher J.; Vaughn, Samuel E.; Marion, Miranda; Weirauch, Matthew T.; Namjou, Bahram; Adler, Adam; Rasmussen, Astrid; Glenn, Stuart; Montgomery, Courtney G.; Hirschfield, Gideon M.; Xie, Gang; Coltescu, Catalina; Amos, Chris; Li, He; Ice, John A.; Nath, Swapan K.; Mariette, Xavier; Bowman, Simon; Rischmueller, Maureen; Lester, Sue; Brun, Johan G.; Gøransson, Lasse G.; Harboe, Erna; Omdal, Roald; Cunninghame-Graham, Deborah S.; Vyse, Tim; Miceli-Richard, Corinne; Brennan, Michael T.; Lessard, James A.; Wahren-Herlenius, Marie; Kvarnström, Marika; Illei, Gabor G.; Witte, Torsten; Jonsson, Roland; Eriksson, Per; Nordmark, Gunnel; Ng, Wan-Fai; Anaya, Juan-Manuel; Rhodus, Nelson L.; Segal, Barbara M.; Merrill, Joan T.; James, Judith A.; Guthridge, Joel M.; Hal Scofield, R.; Alarcon-Riquelme, Marta; Bae, Sang-Cheol; Boackle, Susan A.; Criswell, Lindsey A.; Gilkeson, Gary; Kamen, Diane L.; Jacob, Chaim O.; Kimberly, Robert; Brown, Elizabeth; Edberg, Jeffrey; Alarcón, Graciela S.; Reveille, John D.; Vilá, Luis M.; Petri, Michelle; Ramsey-Goldman, Rosalind; Freedman, Barry I.; Niewold, Timothy; Stevens, Anne M.; Tsao, Betty P.; Ying, Jun; Mayes, Maureen D.; Gorlova, Olga Y.; Wakeland, Ward; Radstake, Timothy; Martin, Ezequiel; Martin, Javier; Siminovitch, Katherine; Moser Sivils, Kathy L.; Gaffney, Patrick M.; Langefeld, Carl D.; Harley, John B.; Kaufman, Kenneth M.

    2015-01-01

    Exploiting genotyping, DNA sequencing, imputation and trans-ancestral mapping, we used Bayesian and frequentist approaches to model the IRF5–TNPO3 locus association, now implicated in two immunotherapies and seven autoimmune diseases. Specifically, in systemic lupus erythematosus (SLE), we resolved separate associations in the IRF5 promoter (all ancestries) and with an extended European haplotype. We captured 3230 IRF5–TNPO3 high-quality, common variants across 5 ethnicities in 8395 SLE cases and 7367 controls. The genetic effect from the IRF5 promoter can be explained by any one of four variants in 5.7 kb (P-valuemeta = 6 × 10−49; OR = 1.38–1.97). The second genetic effect spanned an 85.5-kb, 24-variant haplotype that included the genes IRF5 and TNPO3 (P-valuesEU = 10−27–10−32, OR = 1.7–1.81). Many variants at the IRF5 locus with previously assigned biological function are not members of either final credible set of potential causal variants identified herein. In addition to the known biologically functional variants, we demonstrated that the risk allele of rs4728142, a variant in the promoter among the lowest frequentist probability and highest Bayesian posterior probability, was correlated with IRF5 expression and differentially binds the transcription factor ZBTB3. Our analytical strategy provides a novel framework for future studies aimed at dissecting etiological genetic effects. Finally, both SLE elements of the statistical model appear to operate in Sjögren's syndrome and systemic sclerosis whereas only the IRF5–TNPO3 gene-spanning haplotype is associated with primary biliary cirrhosis, demonstrating the nuance of similarity and difference in autoimmune disease risk mechanisms at IRF5–TNPO3. PMID:25205108

  13. The algebra of two-component spinors

    International Nuclear Information System (INIS)

    An overview of the algebra of two-component spinors and of four-component spinors based on abstract linear algebra is given. The role of spinors for the complex Lorentz group and for all of its real forms is worked out. (G.Q.)

  14. Two-component abelian sandpile models

    OpenAIRE

    Alcaraz, F. C.; Pyatov, P.; Rittenberg, V.

    2008-01-01

    In one-component abelian sandpile models, the toppling probabilities are independent quantities. This is not the case in multi-component models. The condition of associativity of the underlying abelian algebras impose nonlinear relations among the toppling probabilities. These relations are derived for the case of two-component quadratic abelian algebras. We show that abelian sandpile models with two conservation laws have only trivial avalanches.

  15. Two-component Abelian sandpile models.

    Science.gov (United States)

    Alcaraz, F C; Pyatov, P; Rittenberg, V

    2009-04-01

    In one-component Abelian sandpile models, the toppling probabilities are independent quantities. This is not the case in multicomponent models. The condition of associativity of the underlying Abelian algebras imposes nonlinear relations among the toppling probabilities. These relations are derived for the case of two-component quadratic Abelian algebras. We show that Abelian sandpile models with two conservation laws have only trivial avalanches. PMID:19518280

  16. Two Component Theory of Neutrino Flavor Mixing

    OpenAIRE

    Sassaroli, Elisabetta

    1997-01-01

    Neutrino flavor mixing is discussed in terms of two-component coupled left-handed flavor fields. This is to take into account the fact that the weak interaction couples only to left-handed fields. The flavor fields are written through a rotation matrix, as a linear combination of left-handed free fields. In order to obtain properly normalized wave functions directly from those free fields, states of mixed helicity have to be considered. Neutrino flavor oscillation amplitudes are also derived.

  17. Temporal and evolutionary dynamics of two-component signaling pathways.

    Science.gov (United States)

    Salazar, Michael E; Laub, Michael T

    2015-04-01

    Bacteria sense and respond to numerous environmental signals through two-component signaling pathways. Typically, a given stimulus will activate a sensor histidine kinase to autophosphorylate and then phosphotransfer to a cognate response regulator, which can mount an appropriate response. Although these signaling pathways often appear to be simple switches, they can also orchestrate surprisingly sophisticated and complex responses. These temporal dynamics arise from several key regulatory features, including the bifunctionality of histidine kinases as well as positive and negative feedback loops. Two-component signaling pathways are also dynamic on evolutionary time-scales, expanding dramatically in many species through gene duplication and divergence. Here, we review recent work probing the temporal and evolutionary dynamics of two-component signaling systems. PMID:25589045

  18. Development and characterization of two-component albedo based neutron individual monitoring system using thermoluminescent detectors; Desenvolvimento e caracterizacao de um sistema de monitoracao individual de neutrons tipo albedo de duas componentes usando detectores termoluminescentes

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Marcelo Marques

    2008-07-01

    A TLD-albedo based two-component neutron individual monitoring system was developed and characterized in this work. The monitor consists of a black plastic holder, an incident neutron boron loaded shield, a moderator polyethylene body (to increase its response), two pairs of TLD-600 and TLD-700 (one pair to each component) and an adjustable belt. This monitoring system was calibrated in thermal neutron fields and in 70 keV, 144 keV, 565 keV, 1.2 MeV and 5 MeV monoenergetic neutron fields. In addition, it was calibrated in {sup 252C}f(D{sub 2}O), {sup 252}Cf, {sup 241}Am-B, {sup 241}Am-Be and {sup 238}Pu-Be source fields. For the latter, the lower detection levels are, respectively, 0.009 mSv, 0.06 mSv, 0.12 mSv, 0.09 mSv and 0.08 mSv. The participation in an international intercomparison sponsored by IAEA with simulated workplace fields validated the system. The monitoring system was successfully characterized in the ISO 21909 standard and in an IRD - the Brazilian Institute for Radioprotection and Dosimetry - technical regulation draft. Nowadays, the neutron individual system is in use by IRD for whole body individual monitoring of five institutions, which comprehend several activities. (author)

  19. Two-component model of solar plages

    Institute of Scientific and Technical Information of China (English)

    LI; Jianping(李建平); DING; Mingde(丁明德); FANG; Cheng(方成)

    2002-01-01

    By use of the 2-m Mcmath-Pierce telescope at Kitt Peak, the high-quality spectra of a plage with moderate brightness near the center of solar disk were obtained. The data include seven spectral lines, which are Hα, Hβ, CaII H and K lines and the infrared triplet. With the consideration of fine structures of solar plages, a two-component atmospheric model is constructed by keeping the cool component to be the quiet atmosphere. Three cases of the hot component are given for different filling factors where the temperature and density distribution are adjusted in order to reproduce the seven observed spectral profiles. We also briefly discuss the influence of the column density at the base of the corona, m0, and the macro-turbulent velocity on the required filling factor and computed profiles. The two-component model is compared with precious one-component semi-empirical models. The limitation of the model is pointed out and further improvement is indicated.

  20. The Legionella pneumophila CpxRA two-component regulatory system: new insights into CpxR's function as a dual regulator and its connection to the effectors regulatory network.

    Science.gov (United States)

    Feldheim, Yaron S; Zusman, Tal; Speiser, Yariv; Segal, Gil

    2016-03-01

    Legionella pneumophila utilizes the Icm/Dot type-IV secretion system to translocate approximately 300 effector proteins into host cells, and the CpxRA two-component system (TCS) was previously shown to regulate the expression of several of these effectors. In this study, we expanded the pool of L. pneumophila CpxR-regulated genes to 38, including 27 effector-encoding genes. Our study demonstrates for the first time that the CpxR dual regulator has different requirements for activation and repression of target genes. These differences include the positioning of the CpxR regulatory element relative to the promoter element, and the effect of CpxR phosphate donors on the expression of CpxR target genes. In addition, unlike most response regulators, a mutant form of the L. pneumophila CpxR which cannot be phosphorylated was found to self-interact, and to repress gene expression similarly to wild-type CpxR, even though its ability to activate gene expression was reduced. Moreover, the CpxRA TCS was found to activate the expression of LetE which was found to function as a connector protein between the CpxRA TCS and the LetAS-RsmYZ-CsrA regulatory cascade. Our results show that CpxR plays a major role in L. pneumophila pathogenesis gene expression and functions as part of a regulatory network. PMID:26713766

  1. The HrpX/HrpY two-component system activates hrpS expression, the first step in the regulatory cascade controlling the Hrp regulon in Pantoea stewartii subsp. stewartii.

    Science.gov (United States)

    Merighi, Massimo; Majerczak, Doris R; Stover, Elizabeth H; Coplin, David L

    2003-03-01

    A regulatory cascade activating hrp/hrc type III secretion and effector genes was delineated in Pantoea stewartii subsp. stewartii, a bacterial pathogen of corn. Four hrp regulatory genes were characterized: hrpX and hrpY encode the sensor kinase and response regulator, respectively, of a two-component signal transduction system; hrpS encodes an NtrC-like transcriptional enhancer; and hrpL encodes an alternative sigma factor. Epistasis analysis, expression studies using gene fusions, and genetic reconstruction of each step in Escherichia coli were used to delineate the following pathway: HrpY activates hrpS and also positively autoregulates the hrpXY operon. In turn, HrpS is required for full activation of the sigma54-dependent hrpL promoter. Finally, HrpL controls expression of all known hrp and wts genes. In vitro, hrpS and all downstream hrp genes were regulated by pH and salt concentration. Mutants with in-frame deletions in hrpX were still partially virulent on corn but were unable to sense the chemical or metabolic signals that induce hrp genes in vitro. Site-directed mutagenesis of HrpY indicated that aspartate 57 is the probable phosphorylation site and that it is needed for activity. These findings suggest that both HrpX and an alternate mechanism are involved in the activation of HrpY in planta. PMID:12650455

  2. Two-component signal transduction system and the virulence-related characteristics of Streptococcus mutans%双组分信号传导系统与变异链球菌的致病相关特性

    Institute of Scientific and Technical Information of China (English)

    陈娇

    2011-01-01

    Two-component signal transduction system (TCSTS) plays an important role in the expression of virulence factors of Streptococcus mutans, such as the competence development, the formation of biofilm, the stability of structure, the production of bacteriocin, and the properties of acid production and resistance. It provides many ecological advantages to compete and survive in the dental plaque. This article is a review about the composition of TCSTS of Streptococcus mutans, the effect of TCSTS on the virulence-related characteristics of Streptococcus mutans, and the application significance of TCSTS.%双组分信号传导系统(TCSTS)在变异链球菌感受态形成、生物膜形成、结构稳定、菌素产生、产酸耐酸特性等毒力因子表达方面起着重要的作用,为其在菌斑生物膜中的竞争和生存提供了诸多生态性优势.本文就变异链球菌TCSTS的组成、TCSTS对变异链球菌致病相关特性的影响、TCSTS的应用意义等作一综述.

  3. The β-propeller gene Rv1057 of Mycobacterium tuberculosis has a complex promoter directly regulated by both the MprAB and TrcRS two-component systems

    Science.gov (United States)

    Pang, Xiuhua; Cao, Guangxiang; Neuenschwander, Pierre F.; Haydel, Shelley E.; Hou, Guihua; Howard, Susan T.

    2011-01-01

    SUMMARY The β-propeller gene Rv1057 of Mycobacterium tuberculosis is activated by envelope stress and was first characterized as a regulatory target of the TrcRS two-component system (TCS). Rv1057 expression is repressed by TrcRS, and the Rv1057 proximal promoter contains a TrcR binding site. In this study, we determined that Rv1057 is also directly regulated by MprAB, a TCS associated with envelope stress. Multiple potential MprA binding sites (MprA boxes) were identified in the 1 kb intergenic region upstream of Rv1057, and four sites were shown to bind MprA. Although MprA boxes were found in the proximal promoter, analyses suggest that MprA and TrcR do not compete for binding in this region. An MprAB-dependent, detergent-inducible transcriptional start point for Rv1057 was identified downstream of the MprA boxes, and a second TrcR binding site and small ORF of the 13E12 family were discovered in the distal promoter. MprAB was required for activation of Rv1057 during growth in macrophages and under detergent stress, and lacZ promoter constructs suggest the entire intergenic region is utilized during MprAB-dependent activation of Rv1057. These findings indicate that Rv1057 has an extensive and complex promoter, and provide evidence for coordinated regulation of stress response genes by TCSs. PMID:22099420

  4. Tobacco two-component gene NTHK2

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By using a previously isolated tobacco two- component gene NTHK1 as a probe, we screened a cDNA library and obtained a homologous gene designated NTHK2. Sequencing analysis revealed that NTHK2 encoded a putative ethylene receptor homolog and contained a histidine kinase domain and a receiver domain. In the histidine kinase domain, the histidine at the phosphorylation site was replaced by an asparagine. Southern analysis indicated that NTHK2 was present at low copies in tobacco genome. The expression of NTHK2 was studied using a competitive RT-PCR method. It was found that, in young flower buds, NTHK2 was expressed abundantly, while in other organs or tissues, it was expressed in a low level. When leaf was subjected to wounding (cutting) treatment, NTHK2 expression was increased. When tobacco seedlings were stressed with PEG and heat shock, NTHK2 transcription was also enhanced. Other treatments showed little effects. These results indicated that NTHK2 might be involved in the developmental processes and in plant responses to some environmental stresses.

  5. The PorX Response Regulator of the Porphyromonas gingivalis PorXY Two-Component System Does Not Directly Regulate the Type IX Secretion Genes but Binds the PorL Subunit

    Science.gov (United States)

    Vincent, Maxence S.; Durand, Eric; Cascales, Eric

    2016-01-01

    The Type IX secretion system (T9SS) is a versatile multi-protein complex restricted to bacteria of the Bacteriodetes phylum and responsible for the secretion or cell surface exposition of diverse proteins that participate to S-layer formation, gliding motility or pathogenesis. The T9SS is poorly characterized but a number of proteins involved in the assembly of the secretion apparatus in the oral pathogen Porphyromonas gingivalis have been identified based on genome substractive analyses. Among these proteins, PorY, and PorX encode typical two-component system (TCS) sensor and CheY-like response regulator respectively. Although the porX and porY genes do not localize at the same genetic locus, it has been proposed that PorXY form a bona fide TCS. Deletion of porX in P. gingivalis causes a slight decrease of the expression of a number of other T9SS genes, including sov, porT, porP, porK, porL, porM, porN, and porY. Here, we show that PorX and the soluble cytoplasmic domain of PorY interact. Using electrophoretic mobility shift, DNA-protein co-purification and heterologous host expression assays, we demonstrate that PorX does not bind T9SS gene promoters and does not directly regulate expression of the T9SS genes. Finally, we show that PorX interacts with the cytoplasmic domain of PorL, a component of the T9SS membrane core complex and propose that the CheY-like PorX protein might be involved in the dynamics of the T9SS.

  6. Relaxation times hierarchy in two-component quasiparticle gas

    OpenAIRE

    Alexander V. Zhukov

    2001-01-01

    A quasiparticle description of various condensed media is a very popular tool in study of their transport and thermodynamic properties. I present here a microscopic theory for the description of diffusion processes in two-component gas of quasiparticles with arbitrary dispersion law and statistics. Particularly, I analyze the role of interaction within each subsystem (i.e. between identical quasiparticles) in relaxation of the whole system. The approach for solution of such kinetic problem al...

  7. Effects of the two-component system comprising GacA and GacS of Erwinia carotovora subsp. carotovora on the production of global regulatory rsmB RNA, extracellular enzymes, and harpinEcc.

    Science.gov (United States)

    Cui, Y; Chatterjee, A; Chatterjee, A K

    2001-04-01

    Posttranscriptional regulation mediated by the regulator of secondary metabolites (RSM) RsmA-rsmB pair is the most important factor in the expression of genes for extracellular enzymes and HarpinEcc in Erwinia carotovora subsp. carotovora. RsmA is a small RNA-binding protein, which acts by lowering the half-life of a mRNA species. rsmB specifies an untranslated regulatory RNA and neutralizes the RsmA effect. It has been speculated that GacA-GacS, members of a two-component system, may affect gene expression via RsmA. Because expA, a gacA homolog, and expS (or rpfA), a gacS homolog, have been identified in E. carotovora subsp. carotovora, we examined the effects of these gacA and gacS homologs on the expression of rsmA, rsmB, and an assortment of exoprotein genes. The gacA gene of E. carotovora subsp. carotovora strain 71 stimulated transcription of genes for several extracellular enzymes (pel-1, a pectate lyase gene; peh-1, a polygalacturonase gene; and celV, a cellulase gene), hrpNEcc (an E. carotovora subsp. carotovora gene specifying the elicitor of hypersensitive reaction), and rsmB in GacA+ and GacS+ E. carotovora subsp. carotovora strains. Similarly, the E. carotovora subsp. carotovora gacA gene stimulated csrB (rsmB) transcription in Escherichia coli. A GacS- mutant of E. carotovora subsp. carotovora strain AH2 and a GacA- mutant of E. carotovora subsp. carotovora strain Ecc71 compared with their parent strains produced very low levels of rsmB, pel-1, peh-1, celV, and hrpNEcc transcripts but produced similar levels of rsmA RNA and RsmA protein as well as transcripts of hyperproduction of extracellular enzymes (Hex) hexA, kdgR (repressor of genes for uronate and pectate catabolism), rsmC, and rpoS (gene for Sigma-S, an alternate Sigma factor). The levels of rsmB, pel-1, peh-1, celV, and hrpNEcc transcripts as well as production of pectate lyase, polygalacturonase, cellulase, protease, and HarpinEcc proteins were stimulated in GacS- and GacA- mutants by Gac

  8. Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Kevin Patel

    2016-03-01

    Full Text Available The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the expression of cidABC and lrgAB operons, the gene products of which are involved in programmed cell death and lysis. In vivo studies have demonstrated involvement of two overlapping regulatory networks in regulating the lrgAB operon, both depending on LytR. One regulatory network responds to glucose metabolism and the other responds to changes in the cell membrane potential. Herein, we show that LytS has autokinase activity and can catalyze a fast phosphotransfer reaction, with 50% of its phosphoryl group lost within 1 minute of incubation with LytR. LytS has also phosphatase activity. Notably, LytR undergoes phosphorylation by acetyl phosphate at a rate that is 2-fold faster than the phosphorylation by LytS. This observation is significant in lieu of the in vivo observations that regulation of the lrgAB operon is LytR-dependent in the presence of excess glucose in the medium. The latter condition does not lead to perturbation of the cell membrane potential but rather to the accumulation of acetate in the cell. Our study provides insights into the molecular basis for regulation of lrgAB in a LytR-dependent manner under conditions that do not involve sensing by LytS.

  9. Dispersionless Hirota Equations of Two-Component BKP Hierarchy

    Directory of Open Access Journals (Sweden)

    Kanehisa Takasaki

    2006-05-01

    Full Text Available The BKP hierarchy has a two-component analogue (the 2-BKP hierarchy. Dispersionless limit of this multi-component hierarchy is considered on the level of the τ-function. The so called dispersionless Hirota equations are obtained from the Hirota equations of the τ-function. These dispersionless Hirota equations turn out to be equivalent to a system of Hamilton-Jacobi equations. Other relevant equations, in particular, dispersionless Lax equations, can be derived from these fundamental equations. For comparison, another approach based on auxiliary linear equations is also presented.

  10. Dynamic structure factors in two-component plasmas

    International Nuclear Information System (INIS)

    Theoretical investigations into the properties of dense plasmas have benefited from results of computer simulations of model systems. Recently molecular simulations of a strongly coupled hydrogen plasma have been performed in which the particals interact via pseudopotentials designed to approximately include short-range quantum effects. Among the simulation results of this two-component plasma (TCP) is the charge-charge structure factor, S /sub QQ/ (k,ω). Here the authors investigate this quantity by approximate solutions to the exact kinetic equation for S /sub QQ/ (k,μ). The equilibrium correlation, S /sub QQ/ (k), valid for strongly coupled systems required as input to the calculation of the dynamic correlation function is found employing the pseudopotential in the solution of the hypernetted chain (HNC) equations. The results are compared with the computer simulation results

  11. Topological Objects in Two-component Bose-Einstein Condensates

    OpenAIRE

    Cho, Y. M.; Khim, Hyojoong; Zhang, Pengming

    2005-01-01

    We study the topological objects in two-component Bose-Einstein condensates. We compare two competing theories of two-component Bose-Einstein condensate, the popular Gross-Pitaevskii theory and the recently proposed gauge theory of two-component Bose-Einstein condensate which has an induced vorticity interaction. We show that two theories produce very similar topological objects, in spite of the obvious differences in dynamics. Furthermore we show that the gauge theory of two-component Bose-E...

  12. How insects overcome two-component plant chemical defence

    DEFF Research Database (Denmark)

    Pentzold, Stefan; Zagrobelny, Mika; Rook, Frederik;

    2014-01-01

    , before and during feeding as well as during digestion, and at several levels such as the insects’ feeding behaviour, physiology and metabolism. Insect adaptations frequently circumvent or counteract the activity of the plant β-glucosidases, bioactivating enzymes that are a key element in the plant’s two......-component chemical defence. These adaptations include host plant choice, non-disruptive feeding guilds and various physiological adaptations as well as metabolic enzymatic strategies of the insect’s digestive system. Furthermore, insect adaptations often act in combination, may exist in both generalists and...... studies are suggested to investigate in detail how insect adaptations act in combination to overcome plant chemical defences and to allow ecologically relevant conclusions....

  13. Determinants of specificity in two-component signal transduction.

    Science.gov (United States)

    Podgornaia, Anna I; Laub, Michael T

    2013-04-01

    Maintaining the faithful flow of information through signal transduction pathways is critical to the survival and proliferation of organisms. This problem is particularly challenging as many signaling proteins are part of large, paralogous families that are highly similar at the sequence and structural levels, increasing the risk of unwanted cross-talk. To detect environmental signals and process information, bacteria rely heavily on two-component signaling systems comprised of sensor histidine kinases and their cognate response regulators. Although most species encode dozens of these signaling pathways, there is relatively little cross-talk, indicating that individual pathways are well insulated and highly specific. Here, we review the molecular mechanisms that enforce this specificity. Further, we highlight recent studies that have revealed how these mechanisms evolve to accommodate the introduction of new pathways by gene duplication. PMID:23352354

  14. Exact two-component relativistic energy band theory and application

    International Nuclear Information System (INIS)

    An exact two-component (X2C) relativistic density functional theory in terms of atom-centered basis functions is proposed for relativistic calculations of band structures and structural properties of periodic systems containing heavy elements. Due to finite radial extensions of the local basis functions, the periodic calculation is very much the same as a molecular calculation, except only for an Ewald summation for the Coulomb potential of fluctuating periodic monopoles. For comparison, the nonrelativistic and spin-free X2C counterparts are also implemented in parallel. As a first and pilot application, the band gaps, lattice constants, cohesive energies, and bulk moduli of AgX (X = Cl, Br, I) are calculated to compare with other theoretical results

  15. Exact two-component relativistic energy band theory and application

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Rundong; Zhang, Yong; Xiao, Yunlong; Liu, Wenjian, E-mail: liuwj@pku.edu.cn [Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, and Center for Computational Science and Engineering, Peking University, Beijing 100871 (China)

    2016-01-28

    An exact two-component (X2C) relativistic density functional theory in terms of atom-centered basis functions is proposed for relativistic calculations of band structures and structural properties of periodic systems containing heavy elements. Due to finite radial extensions of the local basis functions, the periodic calculation is very much the same as a molecular calculation, except only for an Ewald summation for the Coulomb potential of fluctuating periodic monopoles. For comparison, the nonrelativistic and spin-free X2C counterparts are also implemented in parallel. As a first and pilot application, the band gaps, lattice constants, cohesive energies, and bulk moduli of AgX (X = Cl, Br, I) are calculated to compare with other theoretical results.

  16. Budding Transition of Asymmetric Two-component Lipid Domains

    CERN Document Server

    Wolff, Jean; Andelman, David

    2016-01-01

    We propose a model that accounts for the budding transition of asymmetric two-component lipid domains, where the two monolayers (leaflets) have different average compositions controlled by independent chemical potentials. Assuming a coupling between the local curvature and local lipid composition in each of the leaflets, we discuss the morphology and thermodynamic behavior of asymmetric lipid domains. The membrane free-energy contains three contributions: the bending energy, the line tension, and a Landau free-energy for a lateral phase separation. Within a mean-field treatment, we obtain various phase diagrams containing fully budded, dimpled, and flat states as a function of the two leaflet compositions. The global phase behavior is analyzed, and depending on system parameters, the phase diagrams include one-phase, two-phase and three-phase regions. In particular, we predict various phase coexistence regions between different morphologies of domains, which may be observed in multi-component membranes or ves...

  17. Stability of Two-Component Bose-Einstein Condensates in Bessel Optical Lattices

    Institute of Scientific and Technical Information of China (English)

    FU Hong-Zhi; CHEN Hai-Jun; LI De-Hua; LI Hao-Cai; PENG Feng; XUE Ju-Kui; GAO Tao; CHENG Xin-Lu

    2008-01-01

    The stability of the ground state of two-component Bose-Einstein condensates (BECs) loaded into the central well of an axially symmetric Bessel lattices (BLs) potential with attractive or repulsive atoms interactions is studied using the time-dependent Gross-Pitaevskii equation (GPE). By using the variational method, we find that stable ground state of two-component BECs can exist in BLs. The BLs's depth and the intra-species atom interaction play an important role in the stability of ground state. The collapse of two-component BECs in BLs is also studied and a collapse condition for trapped two-component BECs is obtained. It is shown that the two-component BECs exhibit rich collapse dynamics. That is, the two-component BECs can collapse in the system with both intra- and inter-attractive, or with intra-attractive and inter-repulsive, or with intra-repulsive and inter-attractive atom interactions. Furthermore, the control of the collapse of the two-component BECs in BLs is discussed in detail The stability diagram of the ground state in parameter space is obtained. The results show that the collapse of two-component BECs can be controlled by temporal modulation of the atom interaction.

  18. An Introductory Idea for Teaching Two-Component Phase Diagrams

    Science.gov (United States)

    Peckham, Gavin D.; McNaught, Ian J.

    2011-01-01

    The teaching of two-component phase diagrams has attracted little attention in this "Journal," and it is hoped that this article will make a useful contribution. Current physical chemistry textbooks describe two-component phase diagrams adequately, but do so in a piecemeal fashion one section at a time; first solid-liquid equilibria, then…

  19. Two-component micro injection moulding for hearing aid applications

    DEFF Research Database (Denmark)

    Islam, Aminul; Hansen, Hans Nørgaard; Marhöfer, David Maximilian;

    2012-01-01

    Two-component (2k) injection moulding is an important process technique at the present state of technology, and it is growing rapidly in the field of precision micro moulding. Besides combining different material properties in the same product, two-component moulding can eliminate many assembly s...

  20. Role of functionality in two-component signal transduction: A stochastic study

    Science.gov (United States)

    Maity, Alok Kumar; Bandyopadhyay, Arnab; Chaudhury, Pinaki; Banik, Suman K.

    2014-03-01

    We present a stochastic formalism for signal transduction processes in a bacterial two-component system. Using elementary mass action kinetics, the proposed model takes care of signal transduction in terms of a phosphotransfer mechanism between the cognate partners of a two-component system, viz., the sensor kinase and the response regulator. Based on the difference in functionality of the sensor kinase, the noisy phosphotransfer mechanism has been studied for monofunctional and bifunctional two-component systems using the formalism of the linear noise approximation. Steady-state analysis of both models quantifies different physically realizable quantities, e.g., the variance, the Fano factor (variance/mean), and mutual information. The resultant data reveal that both systems reliably transfer information of extracellular environment under low external stimulus and in a high-kinase-and-phosphatase regime. We extend our analysis further by studying the role of the two-component system in downstream gene regulation.

  1. Travelling wave solutions for some two-component shallow water models

    Science.gov (United States)

    Dutykh, Denys; Ionescu-Kruse, Delia

    2016-07-01

    In the present study we perform a unified analysis of travelling wave solutions to three different two-component systems which appear in shallow water theory. Namely, we analyze the celebrated Green-Naghdi equations, the integrable two-component Camassa-Holm equations and a new two-component system of Green-Naghdi type. In particular, we are interested in solitary and cnoidal-type solutions, as two most important classes of travelling waves that we encounter in applications. We provide a complete phase-plane analysis of all possible travelling wave solutions which may arise in these models. In particular, we show the existence of new type of solutions.

  2. Preparation and frictional investigation of the two-components silanes deposited on alumina surface

    International Nuclear Information System (INIS)

    Highlights: • The two-component silane films on the alumina surface were obtained by a combination of soft lithography and vapor phase deposition method. • The effectiveness of modification procedure was monitored by AFM topography images. • By using gas phase deposition method succeeded in obtaining a good reproduction of pattern. • Silane films with low surface free energy and coefficient of friction values were obtained. • The frictional performance in milli-Newton load range of one- and two-component films was investigated by microtribometry. - Abstract: Functionalization and pattering technique that permits two-component pattern-specific modification of alumina surface with silanes molecules are reported. The method relies on a two-component molecular system that simultaneously decreases coefficient of friction of the alumina surface and provides uniform chemical functionality suitable for further elaboration. Pattern/two-component modification is achieved via gas-phase deposition of the silanes using polydimethylsiloxane stamp. The frictional behaviors of the two-component films of the silane molecules with different chain length covalently absorbed on alumina surfaces, were characterized by the ball-disk (microtribometer) tester. The surfaces of the substrate modified by two-component molecular films were examined by atomic force microscopy (AFM). The measured tribological results showed that the mixing of the fluoroalkylsilane and alkylsilane enhance the lubrication and decrease the friction compared to the one-component thin films

  3. Exploring a minimal two-component p53 model

    International Nuclear Information System (INIS)

    The tumor suppressor p53 coordinates many attributes of cellular processes via interlocked feedback loops. To understand the biological implications of feedback loops in a p53 system, a two-component model which encompasses essential feedback loops was constructed and further explored. Diverse bifurcation properties, such as bistability and oscillation, emerge by manipulating the feedback strength. The p53-mediated MDM2 induction dictates the bifurcation patterns. We first identified irradiation dichotomy in p53 models and further proposed that bistability and oscillation can behave in a coordinated manner. Further sensitivity analysis revealed that p53 basal production and MDM2-mediated p53 degradation, which are central to cellular control, are most sensitive processes. Also, we identified that the much more significant variations in amplitude of p53 pulses observed in experiments can be derived from overall amplitude parameter sensitivity. The combined approach with bifurcation analysis, stochastic simulation and sampling-based sensitivity analysis not only gives crucial insights into the dynamics of the p53 system, but also creates a fertile ground for understanding the regulatory patterns of other biological networks

  4. Local-field effect in atom optics of two-component Bose-Einstein condensates

    OpenAIRE

    K.V.Krutitsky; Marzlin, K. -P.; Audretsch, J.

    2000-01-01

    Starting from the first principles of nonrelativistic QED we have developed the quantum theory of the interaction of a two-component ultracold atomic ensemble with the electromagnetic field of vacuum and laser photons. The main attention has been paid to the consistent consideration of dynamical dipole-dipole interactions in the radiation field. Taking into account local-field effects we have derived the system of Maxwell-Bloch equations. Optical properties of the two-component Bose gas are i...

  5. Study on diffusion and natural circulation of two component gases

    International Nuclear Information System (INIS)

    When a primary coolant pipe of a High Temperature Gas Cooled Reactor (HTGR) ruptures, helium gas in the reactor core blows out into the container, and the primary coolant system reduces the pressure. After the reactor core and the container pressures are balanced, air is expected to ingress into the reactor core from a broken part by natural circulation and diffusion. It seems to be probable that the graphite structures is oxidized by the air. It is difficult to predict the air ingress rate, because complicated natural circulations take place in the reactor core, and diffusion paths are also complicated. In order to study the basic features of the air ingress during the early stage of the primary pipe rupture accident of the high temperature gas cooled reactor, the natural circulation of the two component gases was studied experimentally and analytically. The experiment was performed with a reversed U-shaped round pipe with one pipe heated and the other cooled. The analytical results were in good agreement with the experimental ones. (author)

  6. Vortons in two component Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Ever since Witten's paper on superconducting cosmic strings, there has been an interest in strings with a non-trivial core structure. In particular, it is believed that such strings can form loops, known as vortons, which are stabilized against shrinking by current and charge trapped on the string world-sheet. In this paper, we show that analogous non-trivial vortices and stable vortex loops exist in non-relativistic two-component atomic Bose-Einstein condensates. In contrast with well-studied superfluid 4He, where similar vortex rings can be stable due to Magnus force only if they move, the vortex rings in two-component BECs can be stable even if they are at rest. We speculate that such vortons may have been already observed in the laboratory. Thus, it may be possible to test predictions regarding vortons in cosmology and astrophysics by doing controlled experiments in two-component BECs. (author)

  7. Two component micro injection moulding for moulded interconnect devices

    DEFF Research Database (Denmark)

    Islam, Aminul

    2008-01-01

    polymers and a reasonable adhesion between them. • Selective metallization of the two component plastic part (coating one polymer with metal and leaving the other one uncoated) To overcome these two main issues in MID fabrication for micro applications, the current Ph.D. project explores the technical...... moulding and selective metallization. Integrated knowledge about the materials, tooling, process conditions and product development is needed. The main issues to be taken into account for two component injection moulded MIDs are: • Two component injection moulding with a sharp interface between the two...... metallization. Several untraditional material pairs have been proven successful in the experiments. The experimental results find the factors which can effectively control the adhesion and interface quality between two polymers. Investigations on the selective metallization process, by two different methods...

  8. An upper mass bound of a two-component protogalaxy

    CERN Document Server

    Miyahata, K; Miyahata, Keiko; Ikeuchi, Satoru

    1995-01-01

    We investigate the physical properties of a two-component virialized protogalaxy comprising a hot gas and cold clouds which are in pressure equilibrium under the assumptions that the protogalaxy is both spherical and homogeneous. Two conditions which we adopt are that the protogalaxy is in virial equilibrium and that the cooling time is less than the dynamical time. It is found that there exists an upper mass bound for such a two-component protogalaxy when the cloud mass is comparable to or greater than that of hot gas. We also consider the stability of the cold cloud against the Jeans instability and Kelvin-Helmholtz instability.

  9. Spontaneous mutations in the CsrRS two-component regulatory system of Streptococcus pyogenes result in enhanced virulence in a murine model of skin and soft tissue infection.

    Science.gov (United States)

    Engleberg, N C; Heath, A; Miller, A; Rivera, C; DiRita, V J

    2001-04-01

    CsrS/CsrR is a 2-component system in Streptococcus pyogenes that negatively regulates hyaluronic capsule and several exotoxins. To detect spontaneous mutations in csrRS, mucoid and large colony variants of M1 strain MGAS166 were isolated from experimental murine skin infections. By use of complementation with a csrRS(+) plasmid, relevant mutations were also detected in 7 of 12 human clinical isolates. The presence of spontaneous mutants in mouse infection was associated with larger, more necrotic lesions. Most spontaneous changes in CsrR resulted from single amino acid substitutions, whereas most csrS mutations were frameshift or nonsense mutations. In 2 instances, IS1548 insertions were found in csrS. Experimental inoculation of mixtures of wild-type (wt) and csrRS(-) bacteria yielded larger, more necrotic lesions than did either strain at twice the inoculum, which suggests that these variants may exhibit pathogenic synergy. Spontaneous emergence of csrRS(-) mutants in vivo enhances the virulence of wt bacteria and increases severity of murine skin infection. PMID:11237829

  10. Phase separation and dynamics of two-component Bose-Einstein condensates

    DEFF Research Database (Denmark)

    Lee, Kean Loon; Jørgensen, Nils Byg; Liu, I-Kang;

    2016-01-01

    The miscibility of two interacting quantum systems is an important testing ground for the understanding of complex quantum systems. Two-component Bose-Einstein condensates enable the investigation of this scenario in a particularly well controlled setting. In a homogeneous system, the transition ...

  11. Entanglement Properties in Two-Component Bose-Einstein Condensate

    Science.gov (United States)

    Jiang, Di-You

    2016-05-01

    We investigate entanglement inseparability and bipartite entanglement of in two-component Bose-Einstein condensate in the presence of the nonlinear interatomic interaction, interspecies interaction. Entanglement inseparability and bipartite entanglement have the similar properties. More entanglement can be generated by adjusting the nonlinear interatomic interaction and control the time interval of the entanglement by adjusting interspecies interaction.

  12. Two-component microinjection moulding for MID fabrication

    DEFF Research Database (Denmark)

    Islam, Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben;

    2010-01-01

    -component injection moulding and subsequent metallisation. This technology promises cost effective and convergent manufacturing approaches for both macro- and microapplications. This paper presents the results of industrial MID production based on two-component injection moulding and discusses the important issues...

  13. Temporal and Evolutionary Dynamics of Two-Component Signaling Pathways

    OpenAIRE

    Salazar, Michael E.; Laub, Michael T.

    2015-01-01

    Bacteria sense and respond to numerous environmental signals through two-component signaling pathways. Typically, a given stimulus will activate a sensor histidine kinase to autophosphorylate and then phosphotransfer to a cognate response regulator, which can mount an appropriate response. Although these signaling pathways often appear to be simple switches, they can also orchestrate surprisingly sophisticated and complex responses. These temporal dynamics arise from several key regulatory fe...

  14. Numerical investigation of the evaporation of two-component droplets

    OpenAIRE

    Strotos, G.; Gavaises, M.; Theodorakakos, A.; Bergeles, G.

    2011-01-01

    A numerical model for the complete thermo-fluid-dynamic and phase-change transport processes of two-component hydrocarbon liquid droplets consisting of n-heptane, n-decane and mixture of the two in various compositions is presented and validated against experimental data. The Navier–Stokes equations are solved numerically together with the VOF methodology for tracking the droplet interface, using an adaptive local grid refinement technique. The energy and concentration equations inside the li...

  15. Parallel TREE code for two-component ultracold plasma analysis

    OpenAIRE

    Jeon, Byoungseon; Kress, Joel D.; Collins, Lee A.; Grønbech-Jensen, Niels

    2007-01-01

    The TREE method has been widely used for long-range interaction {\\it N}-body problems. We have developed a parallel TREE code for two-component classical plasmas with open boundary conditions and highly non-uniform charge distributions. The program efficiently handles millions of particles evolved over long relaxation times requiring millions of time steps. Appropriate domain decomposition and dynamic data management were employed, and large-scale parallel processing was achieved using an int...

  16. A two-component rain model for the prediction of attenuation statistics

    Science.gov (United States)

    Crane, R. K.

    1982-01-01

    A two-component rain model has been developed for calculating attenuation statistics. In contrast to most other attenuation prediction models, the two-component model calculates the occurrence probability for volume cells or debris attenuation events. The model performed significantly better than the International Radio Consultative Committee model when used for predictions on earth-satellite paths. It is expected that the model will have applications in modeling the joint statistics required for space diversity system design, the statistics of interference due to rain scatter at attenuating frequencies, and the duration statistics for attenuation events.

  17. Persistent currents in a two-component Bose–Einstein condensate confined in a ring potential

    International Nuclear Information System (INIS)

    We present variational and numerical solutions for the problem of stability of persistent currents in a two-component Bose–Einstein condensate of distinguishable atoms which rotate in a ring potential. We consider the general class of solutions of constant density in the two components separately, thus providing an alternative approach to the solution of the same problem given recently by Wu and Zaremba (2013 Phys. Rev. A 88 063640). Our approach provides a physically transparent solution for this delicate problem. Finally, we give a unified and simple picture of the lowest energy state of the system for large values of the coupling. (paper)

  18. Modulational instability of two-component Bose-Einstein condensates in an optical lattice

    International Nuclear Information System (INIS)

    We study modulational instability of two-component Bose-Einstein condensates in an optical lattice, which is modeled as a coupled discrete nonlinear Schroedinger (DNLS) equation. The excitation spectrum and the modulational instability condition of the total system are presented analytically. In the long-wavelength limit, our results agree with the homogeneous two-component Bose-Einstein condensates case. The discreteness effects result in the appearance of the modulational instability for the condensates in miscible region. The numerical calculations confirm our analytical results and show that the interspecies coupling can transfer the instability from one component to another

  19. Light Responsive Two-Component Supramolecular Hydrogel: A Sensitive Platform for Humidity Sensors

    KAUST Repository

    Samai, Suman

    2016-02-15

    The supramolecular assembly of anionic azobenzene dicarboxylate and cationic cetyltrimethylammonium bromide (CTAB) formed a stimuli responsive hydrogel with a critical gelation concentration (CGC) of 0.33 wt%. This self-sustainable two-component system was able to repair damage upon light irradiation. Moreover, it was successfully employed in the fabrication of highly sensitive humidity sensors for the first time.

  20. Two component micro injection molding for MID fabrication

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben

    2009-01-01

    Molded Interconnect Devices (MIDs) are plastic substrates with electrical infrastructure. The fabrication of MIDs is usually based on injection molding and different process chains may be identified from this starting point. The use of MIDs has been driven primarily by the automotive sector, but...... recently the medical sector seems more and more interested. In particular the possibility of miniaturization of 3D components with electrical infrastructure is attractive. The paper describes possible manufacturing routes and challenges of miniaturized MIDs based on two component micro injection molding...

  1. Measurement of two-component flow using ultrasonic flowmeters

    Science.gov (United States)

    Whitehouse, J. C.; Eghbali, D. A.; Flitton, V. E.; Anderson, D. G.

    Calibration of transit-time and Doppler ultrasonic flowmeters under two-component flow conditions has been conducted on 400 mm (16-in.) pipe. Testing covered total flows of 0.19 to 1.89 m(exp 3)/s (3000 to 30,000 gpm) and void fractions up to 40 percent. Both flowmeter types accurately measured total volumetric flow over a portion of their ranges. Pipe average void fraction, based on a three-beam gamma densitometer, was used to determine water component flow under stratified flow conditions, with similar results.

  2. Two component dark matter with multi-Higgs portals

    CERN Document Server

    Bian, Ligong; Shu, Jing; Wang, Xiao-Chuan

    2014-01-01

    We propose a two component dark matter model with extra hidden gauge group $SU(2)_D$ and a global symmetry $ U(1)$. After the $SU(2)_D\\times U(1)$ symmetry breaking, we obtain both the vector and scalar DM candidates. The two DMs communicate with the standard model (SM) via three Higgs as multi-Higgs portals. The three Higgs are mixing of the SM Higgs, hidden sector doublet and the real part of a supplement complex scalar singlet. We study the dark matter (DM) relic density and direct detection in three scenarios. Resonance behaviors and interaction between the two component DMs are represented through investigation of the relic density in the parameter spaces of the two DMs masses. The electroweak precision parameters constrain the Higgs portals couplings $\\lambda_m$ and $\\delta_2$. The relevant vacuum stability and the naturalness problem in the parameter space of $\\lambda_m$ and $\\delta_2$ are studied as well, the model could alleviate these two problem in some parameter space under constraints of electrow...

  3. Two Component Injection Moulding for Moulded Interconnect Devices

    DEFF Research Database (Denmark)

    Islam, Aminul

    component (2k) injection moulding is one of the most industrially adaptive processes. However, the use of two component injection moulding for MID fabrication, with circuit patterns in sub-millimeter range, is still a big challenge. This book searches for the technical difficulties associated with the...... process and makes attempts to overcome those challenges. In search of suitable polymer materials for MID applications, potential materials are characterized in terms of polymer-polymer bond strength, polymer-polymer interface quality and selective metallization. The experimental results find the factors...... which can effectively control the quality of 2k moulded parts and metallized MIDs. This book presents documented knowledge about MID process chains, 2k moulding and selective metallization which can be valuable source of information for both academic and industrial users....

  4. Two-component wind fields from single scanning aerosol lidar

    Science.gov (United States)

    Mayor, Shane D.; Derian, Pierre; Mauzey, Christopher F.; Hamada, Masaki

    2015-09-01

    An overview of recent research results on the performance of two motion estimation algorithms used to deduce two-component horizontal wind fields from ground-based scanning elastic backscatter lidar is presented. One motion estimation algorithm is a traditional cross-correlation method optimized for atmospheric lidar data. The second algorithm is a recently-developed wavelet-based optical flow. An intercomparison of experimental results with measurements from an independent Doppler lidar over an agricultural area in Chico, California, during daytime convective conditions in 2013-14 are presented. Finally, early results from application of the algorithms to data collected over the ocean from a compact and portable aerosol lidar that was deployed on the northern California coast in March of 2015 are presented.

  5. Bounds to the conductivity of some two-component composites

    Science.gov (United States)

    Helsing, Johan

    1993-02-01

    Calculation of third-order bounds to the conductivity of isotropic two-component composites is discussed. Coincidence of the Beran bounds and bounds derived using trial fields based on the solution of a single-body electrostatic boundary-value problem is demonstrated for a random distribution of impenetrable ellipsoids. This extends a proof of Beasley and Torquato [J. Appl. Phys. 60, 3576 (1986)]. A structural parameter related to third-order bounds is calculated for a face-centered cubic array of cubes in a matrix. For an array of rectangular blocks an upper bound in one direction is derived. This bound, and its two-dimensional analogs, become very sharp in the limit of strong inhomogeneity. Improved third- and fourth-order bounds for the three-dimensional checkerboard are presented.

  6. Chemical evolution of two-component galaxies. II

    International Nuclear Information System (INIS)

    In order to confirm and refine the results obtained in a previous paper the chemical evolution of two-component (spheroid + disk) galaxies is derived rejecting the instantaneous recycling approximation, by means of numerical computations, accounting for (i) the collapse phase of the gas, assumed to be uniform in density and composition, and (ii) a birth-rate stellar function. Computations are performed relatively to the solar neighbourhood and to model galaxies which closely resemble the real morphological sequence: in both cases, numerical results are compared with analytical ones. The numerical models of this paper constitute a first-order approximation, while higher order approximations could be made by rejecting the hypothesis of uniform density and composition, and making use of detailed dynamical models. (Auth.)

  7. Dynamics of two-component membranes surrounded by viscoelastic media

    International Nuclear Information System (INIS)

    We discuss the dynamics of two-component fluid membranes which are surrounded by viscoelastic media. We assume that membrane-embedded proteins can diffuse laterally and induce a local membrane curvature. The mean squared displacement of a tagged membrane segment is obtained as a generalized Einstein relation. When the elasticity of the surrounding media obeys a power-law behavior in frequency, an anomalous diffusion of the membrane segment is predicted. We also consider the situation where the proteins generate active non-equilibrium forces. The generalized Einstein relation is further modified by an effective temperature that depends on the force dipole energy. The obtained generalized Einstein relations are useful for membrane microrheology experiments. (fast track communication)

  8. No electrostatic supersolitons in two-component plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Verheest, Frank, E-mail: frank.verheest@ugent.be [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B–9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Lakhina, Gurbax S., E-mail: lakhina@iigm.iigs.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai (India); Hellberg, Manfred A., E-mail: hellberg@ukzn.ac.za [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)

    2014-06-15

    The concept of acoustic supersolitons was introduced for a very specific plasma with five constituents, and discussed only for a single set of plasma parameters. Supersolitons are characterized by having subsidiary extrema on the sides of a typical bipolar electric field signature, or by association with a root beyond double layers in the fully nonlinear Sagdeev pseudopotential description. It was subsequently found that supersolitons could exist in several plasma models having three constituent species, rather than four or five. In the present paper, it is proved that standard two-component plasma models cannot generate supersolitons, by recalling and extending results already in the literature, and by establishing the necessary properties of a more recent model.

  9. Dynamics of two-component membranes surrounded by viscoelastic media.

    Science.gov (United States)

    Komura, Shigeyuki; Yasuda, Kento; Okamoto, Ryuichi

    2015-11-01

    We discuss the dynamics of two-component fluid membranes which are surrounded by viscoelastic media. We assume that membrane-embedded proteins can diffuse laterally and induce a local membrane curvature. The mean squared displacement of a tagged membrane segment is obtained as a generalized Einstein relation. When the elasticity of the surrounding media obeys a power-law behavior in frequency, an anomalous diffusion of the membrane segment is predicted. We also consider the situation where the proteins generate active non-equilibrium forces. The generalized Einstein relation is further modified by an effective temperature that depends on the force dipole energy. The obtained generalized Einstein relations are useful for membrane microrheology experiments. PMID:26448393

  10. Nonlocal Transport Model for Two-Component Plasmas

    Science.gov (United States)

    Zheng, Zhen

    My PhD thesis concerns nonlocal effects on the transport processes in two-component (electron and ion) plasmas. My objective is to construct a self-consistent nonlocal transport model that is applicable in fully-ionized homogeneous Maxwellian plasmas with small-amplitude perturbations for arbitrary particle collisionalities. The fundamental method starts with a rigorous solution of the full set of linearized Fokker-Planck kinetic equations with the Landau collision operators for two-component plasmas. Then a procedure is implemented for derivation of the linear fluid equations which are closed by the transport relations. Thereby a complete list of transport coefficients for each component is computed in the broad range of temporal and spatial scales. Some new transport coefficients are found from the nonlocal hydrodynamic formulation. Ion collisions are self-consistently included in all the calculations. The electric susceptibilities and dispersion relation can thus be derived from this linear nonlocal hydrodynamics for both isothermal and non-isothermal cases. With the aid of these formulations, some important plasma quantities are successfully calculated and some practical fitting formulae are proposed, i.e., the mode frequencies and damping rates of ion acoustic wave (IAW) and entropy wave (ENW). In addition, this linear nonlocal hydrodynamics has been applied to a derivation of the dynamic form factor S(k,w) that serves to describe and explain correctly the features of the frequency spectra observed in Thomson scattering experiments. The most significant accomplishment in my research work is a thorough investigation and a deep analysis of nonlocal ion effects on longitudinal low-frequency plasma fluctuations.

  11. Bloch Oscillations of Two-Component Bose-Einstein Condensates in Optical Lattices

    Institute of Scientific and Technical Information of China (English)

    GU Huai-Qiang; WANG Zhi-Cheng; JIN Kang; TAN Lei

    2006-01-01

    @@ We study the Bloch oscillations of two-component Bose-Einstein condensates trapped in spin-dependent optical lattices. The influence of the intercomponent atom interaction on the system is discussed in detail Accelerated breakdown of the Bloch oscillations and revival phenomena are found respectively for the repulsive and attractive case. For both the cases, the system will finally be set in a quantum self-trapping state due to dynamical instability.

  12. A minimal model for two-component dark matter

    International Nuclear Information System (INIS)

    We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a Z2 symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatible with all present bounds and examine their direct detection prospects at planned experiments. A generic feature of this model is that both particles give rise to observable signals in 1-ton direct detection experiments. In fact, such experiments will be able to probe even a subdominant dark matter component at the percent level.

  13. Two-component Fermi gas in a one-dimensional harmonic trap

    OpenAIRE

    Xianlong, Gao; Wonneberger, W.

    2001-01-01

    A many body theory for a two-component system of spin polarized interacting fermions in a one-dimensional harmonic trap is developed. The model considers two different states of the same fermionic species and treats the dominant interactions between the two using the bosonization method for forward scattering. Asymptotically exact results for the one-particle matrix elements at zero temperature are given. Using them, occupation probabilities of oscillator states are discussed. Particle and mo...

  14. Crosstalk and the evolution of specificity in two-component signaling

    OpenAIRE

    Rowland, Michael A.; Deeds, Eric J.

    2014-01-01

    The global architectures of signaling networks in bacteria and eukaryotes are remarkably different: crosstalk between pathways is very common in eukaryotes but is very limited in bacteria. Bacteria use two-component signaling (TCS) to transduce information, relying on a single enzyme to act as both kinase and phosphatase for targets. We used mathematical models to show that introducing crosstalk in TCS always decreases system performance. This indicates that the large-scale differences betwee...

  15. The Bound of Entanglement of Superpositions with More Than Two Components

    OpenAIRE

    Xiang, Yang; Xiong, Shi-Jie; Hong, Fang-Yu

    2007-01-01

    A bipartite quantum state (for two systems in any dimensions) can be decomposed as a superposition of many components. For a superposition of more than two components we prove that there is a bound of the entanglement of the superposition state which can be expressed according to entanglements of its component states. Especially, if the component states are mutually bi-orthogonal, the entanglement of the superposition state can be exactly given in terms of the entanglements of the states bein...

  16. Two-component proton spectra in the inner Saturnian magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Krimigis, S.M.; Armstrong, T.P.

    1982-10-01

    The Low Energy Charged Particle (LECP) experiment onboard the Voyager-2 spacecraft performed extensive measurements of energetic (approx.28 keV< or approx. =E/sub p/< or approx. =150 MeV; approx.22 keV< or approx. =E/sub e/< or approx. =20 MeV) protons and electrons during spacecraft passage through the inner magnetosphere of Saturn in August 1981. Analysis of the measurements inside the orbits of Enceladus and Mimas reveals the presence of a two-component proton spectrum consisting of a low-energy population at < or approx. =500 keV identified for the first time and described by dj/dE = KE/sup 2.5/, and a high-energy part at E> or approx. =16 MeV whose spectral form is similar to that expected from cosmic ray neutron albedo decay (CRAND), as previously inferred by the Pioneer-11 investigators from integral measurements. In addition, there exist large fluxes of high (> or approx. =1.5 MeV) and low (22 to 35 keV) energy electrons (approx.3.5 x 10/sup 5/ and approx.1.1 x 10/sup 5/ cm/sup -2/sec/sup -1/sr/sup -1/, respectively) throughout this region. The pitch angle distribution of low energy protons changes from a simple sin/sup 2/3/ ..cap alpha.. dependence to one where intensities near 90/sup 0/ become depleted as the spacecraft approached the planet's ring plane at approx.2.88 R/sub S/. It is likely that the pitch angle depletion is due to proton interactions with the tenuous G-ring. These observations also resolve a number of uncertainties regarding the presence of energetic protons and electrons inside the orbits of Enceladus and Mimas, arising from the analysis of Pioneer-11 measurements.

  17. Substrate temperature controls molecular orientation in two-component vapor-deposited glasses.

    Science.gov (United States)

    Jiang, J; Walters, D M; Zhou, D; Ediger, M D

    2016-04-01

    Vapor-deposited glasses can be anisotropic and molecular orientation is important for organic electronics applications. In organic light emitting diodes (OLEDs), for example, the orientation of dye molecules in two-component emitting layers significantly influences emission efficiency. Here we investigate how substrate temperature during vapor deposition influences the orientation of dye molecules in a model two-component system. We determine the average orientation of a linear blue light emitter 1,4-di-[4-(N,N-diphenyl)amino]styryl-benzene (DSA-Ph) in mixtures with aluminum-tris(8-hydroxyquinoline) (Alq3) by spectroscopic ellipsometry and IR dichroism. We find that molecular orientation is controlled by the ratio of the substrate temperature during deposition and the glass transition temperature of the mixture. These findings extend recent results for single component vapor-deposited glasses and suggest that, during vapor deposition, surface mobility allows partial equilibration towards orientations preferred at the free surface of the equilibrium liquid. PMID:26922903

  18. Different electronic charges in two-component superconductor by coherent state

    International Nuclear Information System (INIS)

    Recently, the different electronic charges, which are related to the different coupling constants with magnetic field, in the two-component superconductor have been studied in the frame of Ginzburg–Landau theory. In order to study the electronic charges in detail we suggest the wave function in the two-component superconductor to be in the coherent state. We find the different electronic charges exist not only in the coherent state but also in the incoherent state. But the ratio of the different charges in the coherent state is different from the ratio in the incoherence. The expressions of the coupling constants are given directly based on the coherence effects. We also discuss the winding number in such a system. - Highlights: • Suggest the wave function in two-component superconductor is coherent. • Interpret the existence of different electric charges by the coherent states. • Derive a new expression for the supercurrent. • Reveal the relation between different electric charges and winding number

  19. Different electronic charges in two-component superconductor by coherent state

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xuguang, E-mail: shixg@bjfu.edu.cn

    2015-07-17

    Recently, the different electronic charges, which are related to the different coupling constants with magnetic field, in the two-component superconductor have been studied in the frame of Ginzburg–Landau theory. In order to study the electronic charges in detail we suggest the wave function in the two-component superconductor to be in the coherent state. We find the different electronic charges exist not only in the coherent state but also in the incoherent state. But the ratio of the different charges in the coherent state is different from the ratio in the incoherence. The expressions of the coupling constants are given directly based on the coherence effects. We also discuss the winding number in such a system. - Highlights: • Suggest the wave function in two-component superconductor is coherent. • Interpret the existence of different electric charges by the coherent states. • Derive a new expression for the supercurrent. • Reveal the relation between different electric charges and winding number.

  20. Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model

    DEFF Research Database (Denmark)

    Özen, C.; Zinner, Nikolaj Thomas

    2014-01-01

    the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of...... a two-component atomic fermi gas in a tight external trap can be mapped to the nuclear shell model so that readily available many-body techniques in nuclear physics, such as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the study of these systems. We demonstrate an...

  1. High-temperature superfluidity of the two-component Bose gas in a transition metal dichalcogenide bilayer

    Science.gov (United States)

    Berman, Oleg L.; Kezerashvili, Roman Ya.

    2016-06-01

    The high-temperature superfluidity of two-dimensional dipolar excitons in two parallel transition metal dichalcogenide (TMDC) layers is predicted. We study Bose-Einstein condensation in the two-component system of dipolar A and B excitons. The effective mass, energy spectrum of the collective excitations, the sound velocity, and critical temperature are obtained for different TMDC materials. It is shown that in the Bogoliubov approximation, the sound velocity in the two-component dilute exciton Bose gas is always larger than in any one-component exciton system. The difference between the sound velocities for two-component and one-component dilute gases is caused by the fact that the sound velocity for a two-component system depends on the reduced mass of A and B excitons, which is always smaller than the individual mass of A or B exciton. Due to this fact, the critical temperature Tc for superfluidity for the two-component exciton system in a TMDC bilayer is about one order of magnitude higher than Tc in any one-component exciton system. We propose to observe the superfluidity of two-dimensional dipolar excitons in two parallel TMDC layers, which causes two opposite superconducting currents in each TMDC layer.

  2. FeuN, a novel modulator of two-component signaling identified in Sinorhizobium meliloti

    OpenAIRE

    Carlyon, Rebecca E.; Ryther, Joanna L.; VanYperen, Ryan D.; Griffitts, Joel S.

    2010-01-01

    Sinorhizobium meliloti is a nitrogen-fixing bacterial symbiont of alfalfa and related legumes. Symbiotic infection by S. meliloti requires an osmosensory two-component system composed of the response regulator FeuP and the sensor kinase FeuQ. The FeuPQ pathway positively regulates transcription of multiple genes including ndvA, which encodes the cyclic glucan exporter. Here we show that proper regulation of this signaling pathway is essential for cell viability. Without the small 83 amino-aci...

  3. Topological phases of two-component bosons in species-dependent artificial gauge potentials

    Science.gov (United States)

    Wu, Ying-Hai; Shi, Tao

    2016-08-01

    We study bosonic atoms with two internal states in artificial gauge potentials whose strengths are different for the two components. A series of topological phases for such systems is proposed using the composite fermion theory and the parton construction. It is found in exact diagonalization that some of the proposed states may be realized for simple contact interaction between bosons. The ground states and low-energy excitations of these states are modeled using trial wave functions. The effective field theories for these states are also constructed and reveal some interesting properties.

  4. Two-component Bose-Hubbard model with higher-angular-momentum states

    Science.gov (United States)

    Pietraszewicz, Joanna; Sowiński, Tomasz; Brewczyk, Mirosław; Zakrzewski, Jakub; Lewenstein, Maciej; Gajda, Mariusz

    2012-05-01

    Bose-Hubbard Hamiltonian of cold two-component Bose gas of spinor chromium atoms is studied. Dipolar interactions of magnetic moments while tuned resonantly by an ultralow magnetic field can lead to a transfer of atoms from the ground to excited Wannier states with a nonvanishing angular orbital momentum. Hence we propose the way of creating Px+iPy orbital superfluid. The spin introduces an additional degree of control and leads to a variety of different stable phases of the system. The Mott insulator of atoms in a superposition of the ground and vortex Wannier states as well as a superposition of the Mott insulator with orbital superfluid are predicted.

  5. Instabilities in relativistic two-component (super)fluids

    CERN Document Server

    Haber, Alexander; Stetina, Stephan

    2016-01-01

    We study two-fluid systems with nonzero fluid velocities and compute their sound modes, which indicate various instabilities. For the case of two zero-temperature superfluids we employ a microscopic field-theoretical model of two coupled bosonic fields, including an entrainment coupling and a non-entrainment coupling. We analyse the onset of the various instabilities systematically and point out that the dynamical two-stream instability can only occur beyond Landau's critical velocity, i.e., in an already energetically unstable regime. A qualitative difference is found for the case of two normal fluids, where certain transverse modes suffer a two-stream instability in an energetically stable regime if there is entrainment between the fluids. Since we work in a fully relativistic setup, our results are very general and of potential relevance for (super)fluids in neutron stars and, in the non-relativistic limit of our results, in the laboratory.

  6. Two-component dual-scatter laser Doppler velocimeter with frequency burst signal readout.

    Science.gov (United States)

    Brayton, D B; Kalb, H T; Crosswy, F L

    1973-06-01

    A dual-scatter laser Doppler velocimeter (LDV) system designed for measuring wind tunnel flow velocity is described. The system simultaneously measures two orthogonal velocity components of a flowing fluid at a common point in the flow. Essential single-velocity component dual-scatter concepts are presented to simplify the description of the more sophisticated two-component system. To implement the two-component system three laser beams with a 0 degrees , 45 degrees , and 90 degrees polarization plane relationship are focused to a common point in the flow by the system-transmitting optics. The beams interfere to form two perpendicular sets of interference fringe planes that are orthogonally polarized. The system-receiving optics collect and separate the orthogonally polarized components of laser radiation scattered from micron-size particles moving with the flowing fluid through the ringes. The system requires no artificial seeding, since intrinsic test section aerosols are utilized for radiation scattering. The passage of each scatter particle through the interference fringes simultaneously produces two frequency-burst-type photodetected signals, the frequencies of which are directly proportional to two perpendicular components of particle velocity. The system photodetection, signal-conditioning, and data acquisition instrumentation is specifically designed to process the frequency burst information in the time domain as opposed to spectrum analysis or frequency domain processing. The system was initially evaluated in an AEDC wind tunnel operating over a Mach number range from 0.6 to 1.5. The LDV and calculated wind tunnel mean velocity data agreed to within 1.25%; flow direction deviations of a few milliradians were resolved. PMID:20125494

  7. The N-soliton solution of a two-component modified nonlinear Schroedinger equation

    International Nuclear Information System (INIS)

    The N-soliton solution is presented for a two-component modified nonlinear Schroedinger equation which describes the propagation of short pulses in birefringent optical fibers. The solution is found to be expressed in terms of determinants. The proof of the solution is carried out by means of an elementary theory of determinants. The generalization of the 2-component system to the multi-component system is discussed as well as a (2+1)-dimensional nonlocal equation arising from its continuum limit. -- Highlights: → The 2-component modified NLS equation has wide applicability in fiber optics. → The N-soliton solution describes the propagation characteristics of any number of optical solitons. → The compact determinantal expression of the solution is presented here for the first time. → The generalization to the multi-component system is proposed as well as its continuum version.

  8. Characterization of a two-component thermoluminescent albedo dosemeter according to ISO 21909

    International Nuclear Information System (INIS)

    A two-component thermoluminescent albedo neutron monitoring system was developed at Instituto de Radioprotecao e Dosimetria, Brazil. As there is no Brazilian regulation for neutron individual monitoring service, the system was tested according to the ISO 21909 standard. This standard provides performance and test requirements for determining the acceptability of personal neutron dosemeters to be used for the measurement of personal dose equivalent, Hp(10), in neutron fields with energies ranging from thermal to 20 MeV. Up to 40 dosemeters were used in order to accomplish satisfactorily the requirements of some tests. Despite operational difficulties, this albedo system passed all ISO 21909 performance requirements. The results and problems throughout this characterization are discussed in this paper.

  9. Phase Separation and Dynamics of two-component Bose-Einstein condensates

    CERN Document Server

    Lee, Kean Loon; Liu, I-Kang; Wacker, Lars; Arlt, Jan J; Proukakis, Nick P

    2016-01-01

    The miscibility of two interacting quantum systems is an important testing ground for the understanding of complex quantum systems. Two-component Bose-Einstein condensates enable the investigation of this scenario in a particularly well controlled setting. In a homogeneous system, the transition between mixed and separated phases is fully characterised by a `miscibility parameter', based on the ratio of intra- to inter-species interaction strengths. Here we show, however, that this parameter is no longer the optimal one for trapped gases, for which the location of the phase boundary depends critically on atom numbers. We demonstrate how monitoring of damping rates and frequencies of dipole oscillations enables the experimental mapping of the phase diagram by numerical implementation of a fully self-consistent finite-temperature kinetic theory for binary condensates. The change in damping rate is explained in terms of surface oscillation in the immiscible regime, and counterflow instability in the miscible reg...

  10. Small two-component Fermi gases in a cubic box with periodic boundary conditions

    Science.gov (United States)

    Yin, X. Y.; Blume, D.

    2013-06-01

    The properties of two-component Fermi gases become universal if the interspecies s-wave scattering length as and the average interparticle spacing are much larger than the range of the underlying two-body potential. Using an explicitly correlated Gaussian basis set expansion approach, we determine the eigenenergies of two-component Fermi gases in a cubic box with periodic boundary conditions as functions of the interspecies s-wave scattering length and the effective range of the two-body potential. The universal properties of systems consisting of up to four particles are determined by extrapolating the finite-range energies to the zero-range limit. We determine the eigenenergies of states with vanishing and finite momenta. In the weakly attractive BCS regime, we analyze the energy spectra and degeneracies using first-order degenerate perturbation theory. Excellent agreement between the perturbative energy shifts and the numerically determined energies is obtained. For the infinitely large scattering length case, we compare our results—where available—with those presented in the literature.

  11. Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation

    International Nuclear Information System (INIS)

    We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy)3 (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its “spin-forbidden” triplet-singlet transition

  12. Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation

    Energy Technology Data Exchange (ETDEWEB)

    Kühn, Michael [Institut für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstraße 12, 76131 Karlsruhe (Germany); Weigend, Florian, E-mail: florian.weigend@kit.edu [Institut für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstraße 12, 76131 Karlsruhe (Germany); Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany)

    2015-01-21

    We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy){sub 3} (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its “spin-forbidden” triplet-singlet transition.

  13. Modulational instability for a self-attractive two-component Bose–Einstein condensate

    International Nuclear Information System (INIS)

    By means of the multiple-scale expansion method, the coupled nonlinear Schrödinger equations without an explicit external potential are obtained in two-dimensional geometry for a self-attractive Bose–Einstein condensate composed of different hyperfine states. The modulational instability of two-component condensate is investigated by using a simple technique. Based on the discussion about two typical cases, the explicit expression of the growth rate for a purely growing modulational instability and the optimum stable conditions are given and analysed analytically. The results show that the modulational instability of this two-dimensional system is quite different from that in a one-dimensional system. (general)

  14. Universal properties of a trapped two-component fermi gas at unitarity.

    Science.gov (United States)

    Blume, D; von Stecher, J; Greene, Chris H

    2007-12-01

    We treat the trapped two-component Fermi system, in which unlike fermions interact through a two-body short-range potential having no bound state but an infinite scattering length. By accurately solving the Schrödinger equation for up to N=6 fermions, we show that no many-body bound states exist other than those bound by the trapping potential, and we demonstrate unique universal properties of the system: Certain excitation frequencies are separated by 2variant Planck's over 2piomega, the wave functions agree with analytical predictions and a virial theorem is fulfilled. Further calculations up to N=30 determine the excitation gap, an experimentally accessible universal quantity, and it agrees with recent predictions based on a density functional approach. PMID:18233361

  15. 生防荧光假单胞菌2 P24中EnvZ/OmpR双因子系统克隆与OmpR原核表达%Cloning of EnvZ/OmpR Two-component System from Pseudomonas fluorescens 2 P24 and Prokaryotic Expression of OmpR

    Institute of Scientific and Technical Information of China (English)

    孙冰冰; 张伟; 段红英; 李伟; 田涛; 张力群

    2014-01-01

    用Mini-Tn5转座子随机突变荧光假单胞菌野生型菌株2P24,得到抗生素2,4二乙酰基间苯三酚(2,4-di-acetylphloroglucinol,2,4-DAPG)产量提高的突变体Sesu-25。对转座子侧翼序列分析表明,转座子插入到EnvZ/OmpR双因子系统的反应调节因子ompR基因。克隆得到包含完整EnvZ/OmpR系统,全长约为5.9 kb的DNA片段。该双因子系统中的envZ基因和ompR基因与P. fluorescens F113的envZ基因和ompR基因同源性分别为93%和96%。将ompR基因克隆到表达载体pET-22b(+)中,得到重组表达载体pET-ompR。将pET-ompR转入Escherichia coli BL21中得到重组菌株BL21-ompR,用IPTG诱导表达和亲和柱层析法纯化的OmpR蛋白,经SDS-PAGE电泳分析表明ompR基因得到成功表达和纯化。%Using the colour of colony as the selective marker, the random mutagenesis of mini-Tn5 was per-formed to wild-type biocontrol strain Pseudomonas fluorescens 2P24 for the screening of mutants,which might have altered yields of polyketide metabolite 2,4-diacetylphloroglucinol(2,4-DAPG). The strain Sesu-25 with a increased yield of 2,4-DAPG was screened from the mutant pool. The analysis of flank sequence of transposon implied that the response regulator OmpR of EnvZ/OmpR two-component regulatory system ( TCS ) was disrupted in mutant strain Sesu-25. A DNA fragment harbouring a intact EnvZ/OmpR TCS was obtained by subcloning. The envZ and ompR of P. fluorescens 2P24 shared a identity of 93% and 96% with P. fluorescens F113,respectively. The ompR was ligated into the expression vector pET-22b( +) to obtain the recombinated plasmid pET-ompR,and the plasmid pET-ompR was transformed into E. coli BL21 to generate the strain BL21-ompR. The His-taged OmpR was purified by affinity chromatography and verified by SDS-PAGE electrophoresis analysis.

  16. Comparison of Dynamical Behaviors Between Monofunctional and Bifunctional Two-Component Signaling Modules

    Science.gov (United States)

    Yang, Xiyan; Wu, Yahao; Yuan, Zhanjiang

    2015-06-01

    Two-component signaling modules exist extensively in bacteria and microbes. These modules can be, based on their distinct network structures, divided into two types: the monofunctional system (denoted by MFS) where the sensor kinase (SK) modulates only phosphorylation of the response regulator (RR), and the bifunctional system (denoted by BFS) where the SK catalyzes both phosphorylation and dephosphorylation of the RR. Here, we analyze dynamical behaviors of these two systems based on stability theory, focusing on differences between them. The analysis of the deterministic behavior indicates that there is no difference between the two modules, that is, each system has the unique stable steady state. However, there are significant differences in stochastic behavior between them. Specifically, if the mean phosphorylated SK level is kept the same for the two modules, then the variance and the Fano factor for the phosphorylated RR in the BFS are always no less than those in the MFS, indicating that bifunctionality always enhances fluctuations. The correlation between the phosphorylated SK and the phosphorylated RR in the BFS is always positive mainly due to competition between system components, but this correlation in the MFS may be positive, almost zero, or negative, depending on the ratio between two rate constants. Our overall analysis indicates that differences between dynamical behaviors of monofunctional and bifunctional signaling modules are mainly in the stochastic rather than deterministic aspect.

  17. Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

    International Nuclear Information System (INIS)

    Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalysts with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a test reaction. It was found that along to both basic components, the system under study also contained the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate was catalytically active. During the first period of the reaction the equilibrium was being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties change rather significantly after thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably connected with the changes in the valence state of the catalytically active components of the catalyst. (author). 5 figs., 4 tabs., 16 refs

  18. Bioorthogonal two-component drug delivery in HER2(+) breast cancer mouse models

    Science.gov (United States)

    Hapuarachchige, Sudath; Kato, Yoshinori; Artemov, Dmitri

    2016-04-01

    The HER2 receptor is overexpressed in approximately 20% of breast cancers and is associated with tumorigenesis, metastasis, and a poor prognosis. Trastuzumab is a first-line targeted drug used against HER2(+) breast cancers; however, at least 50% of HER2(+) tumors develop resistance to trastuzumab. To treat these patients, trastuzumab-based antibody-drug conjugates (ACDs) have been developed and are currently used in the clinic. Despite their high efficacy, the long circulation half-life and non-specific binding of cytotoxic ADCs can result in systemic toxicity. In addition, standard ADCs do not provide an image-guided mode of administration. Here, we have developed a two-component, two-step, pre-targeting drug delivery system integrated with image guidance to circumvent these issues. In this strategy, HER2 receptors are pre-labeled with a functionalized trastuzumab antibody followed by the delivery of drug-loaded nanocarriers. Both components are cross-linked by multiple bioorthogonal click reactions in situ on the surface of the target cell and internalized as nanoclusters. We have explored the efficacy of this delivery strategy in HER2(+) human breast cancer models. Our therapeutic study confirms the high therapeutic efficacy of the new delivery system, with no significant toxicity.

  19. Stationary and oscillatory fronts in a two-component genetic regulatory network model

    Science.gov (United States)

    Hardway, Heather; Li, Yue-Xian

    2010-09-01

    We investigate a two-component gene network model, originally used to describe the spatiotemporal patterning of the gene products in early Drosophila development. By considering a particular mode of interaction between the two gene products, denoted proteins A and B, we find both stable stationary and time-oscillatory fronts can occur in the reaction-diffusion system. We reduce the system by replacing B with its spatial average (shadow system) and assume an abrupt “on-and-off” switch for the genes. In doing so, explicit formula are obtained for all steady-state solutions and their linear eigenvalues. Using the diffusion of A,Da, and the basal production rate, r, as bifurcation parameters, we explore ranges in which a monotone, stationary front is stable, and show it can lose stability through a Hopf bifurcation, giving rise to oscillatory fronts. We also discuss the existence and stability of steady-state and time-oscillatory solutions with multiple extrema. An intuitive explanation for the occurrence of stable stationary and oscillatory front solutions is provided based on the behavior of A in the absence of B and the opposite regulation between A and B. Such behavior is also interpreted in terms of the biological parameters in the model, including those governing the connection of the gene network.

  20. Mechanism and regulation of the Two-component FMN-dependent monooxygenase ActVA-ActVB from Streptomyces coelicolor.

    OpenAIRE

    Valton, Julien; Mathevon, Carole; Fontecave, Marc; Nivière, Vincent; Ballou, David P.

    2008-01-01

    International audience The ActVA-ActVB system from Streptomyces coelicolor is a two-component flavin-dependent monooxygenase involved in the antibiotic actinorhodin biosynthesis. ActVB is a NADH:flavin oxidoreductase that provides a reduced FMN to ActVA, the monooxygenase that catalyzes the hydroxylation of dihydrokalafungin, the precursor of actinorhodin. In this work, using stopped-flow spectrophotometry, we investigated the mechanism of hydroxylation of dihydrokalafungin catalyzed by Ac...

  1. Laser controlling chaotic region of a two-component Bose-Einstein condensate

    Institute of Scientific and Technical Information of China (English)

    Boli Xia; Wenhua Hai

    2005-01-01

    @@ For a weakly and periodically driven two-component Bose-Einstein condensate (BEC) the Melnikov chaotic solution and boundedness conditions are derived from a direct perturbation theory that leads to the chaotic regions in the parameter space.

  2. The rapid control of interactions in a two-component Fermi gas

    Science.gov (United States)

    Stites, Ronald William Donald

    In this dissertation, we describe a variety of experiments having application to ultra-cold atomic gases. While the majority of the experimental results focus on the development of a novel laser source for cooling and manipulating a gas of fermionic 6Li atoms, we also report on a preliminary investigation of rapidly controlling interactions in a two-component Fermi gas. One of the primary tools for our ultra-cold atomic physics experiments is 671 nm laser light nearly resonant with the D1 and D2 spectroscopic lines of ultracold fermionic 6Li atoms. Traditionally, this light is generated using dye lasers or tapered amplifier systems. Here we describe a diode pumped solid state ring laser system utilizing a Nd:YVO 4 gain crystal. Nd:YVO4 has a 4F 3/2 → 4I13/2 emission line at 1342 nm. This wavelength is double the 671 nm needed for our experiments. As a part of this investigation, we also measured the Verdet constant of undoped Y3Al5O12 in the near infrared for constructing a Faraday rotator used to drive unidirectional operation of our ring laser. As an alternative method to achieve unidirectional, single-frequency operation of the laser, we developed a novel scheme of "self-injection locking" where a small portion of the output beam is coupled back into the cavity to break the symmetry. This technique is useful for high-power, single-frequency operation of a ring laser because lossy elements needed for frequency selection and unidirectional operation of the laser can be removed from the internal cavity. In addition to our laser experiments, we also drive Raman transitions between different magnetic hyperfine states within 6Li atoms. For atoms in the two lowest hyperfine states, there exists a broad Feshbach resonance at 834.1 Gauss whereby the s-wave scattering length diverges, resulting in strong interactions between the two species. By using two phase locked lasers to drive a transition from a strongly interacting state to a weakly interacting state, we can

  3. Molecular Mechanism of the Two-Component Suicidal Weapon of Neocapritermes taracua Old Workers.

    Science.gov (United States)

    Bourguignon, Thomas; Šobotník, Jan; Brabcová, Jana; Sillam-Dussès, David; Buček, Aleš; Krasulová, Jana; Vytisková, Blahoslava; Demianová, Zuzana; Mareš, Michael; Roisin, Yves; Vogel, Heiko

    2016-03-01

    In termites, as in many social insects, some individuals specialize in colony defense, developing diverse weaponry. As workers of the termite Neocapritermes taracua (Termitidae: Termitinae) age, their efficiency to perform general tasks decreases, while they accumulate defensive secretions and increase their readiness to fight. This defensive mechanism involves self-sacrifice through body rupture during which an enzyme, stored as blue crystals in dorsal pouches, converts precursors produced by the labial glands into highly toxic compounds. Here, we identify both components of this activated defense system and describe the molecular basis responsible for the toxicity of N. taracua worker autothysis. The blue crystals are formed almost exclusively by a specific protein named BP76. By matching N. taracua transcriptome databases with amino acid sequences, we identified BP76 to be a laccase. Following autothysis, the series of hydroquinone precursors produced by labial glands get mixed with BP76, resulting in the conversion of relatively harmless hydroquinones into toxic benzoquinone analogues. Neocapritermes taracua workers therefore rely on a two-component activated defense system, consisting of two separately stored secretions that can react only after suicidal body rupture, which produces a sticky and toxic cocktail harmful to opponents. PMID:26609080

  4. Surfactant effect on cloud condensation nuclei for two-component internally mixed aerosols

    Science.gov (United States)

    Petters, Sarah Suda; Petters, Markus Dirk

    2016-02-01

    This work presents experimental data on the cloud condensation nuclei (CCN) activity of two-component mixtures containing surfactants. Nine binary systems were tested combining strong ionic (sodium dodecyl sulfate) and nonionic surfactants (Zonyl FS-300 and Triton X-100) with nonsurfactant compounds (glucose, ammonium sulfate, or sodium chloride). Control tests were performed for systems combining organic (glucose) and inorganic compounds (ammonium sulfate or sodium chloride). Results show that CCN activity deviates strongly relative to predictions made from measurements of bulk surface tension. Köhler theory accounting for surface tension reduction and surface partitioning underpredicts the CCN activity of particles containing Zonyl FS-300 and Triton X-100. Partitioning theory better describes data for Zonyl FS-300 and Triton X-100 when limiting surface adsorption to 1.5 monolayers of the growing drop. Deviations from predictions were observed. Likely explanations include solute-solute interactions and nonspherical particle shape. The findings presented here examine in detail the perturbation of CCN activity by surfactants and may offer insight into both the success and limitations of physical models describing CCN activity of surface active molecules.

  5. Non-equilibrium dynamics around integrability in a one-dimensional two-component Bose gas

    Science.gov (United States)

    van Druten, Nicolaas; Wicke, Philipp; Whitlock, Shannon

    2011-05-01

    We investigate a one-dimensional two-component Bose gas near the point of state-independent interactions. At this specific point the system is integrable, in the sense that exact (thermodynamic) Bethe Ansatz solutions can be applied locally. In the experiments, we employ an atom chip and the magnetically trappable clock states in 87Rb. State-dependent potentials are generated by using the polarization dependence of radio-frequency dressing. We show that this allows us to continuously and dynamically tune both the local interactions and the global trapping potential. The experimentally accessible range in interactions includes the region around the integrability point. We study the spin motion that follows upon a sudden change in the system, a quantum quench. When starting from a low-temperature, quantum-degenerate gas in the weakly interacting regime, good agreement with a Gross-Pitaevskii description is found. The experiment allows exploring regimes that go beyond such a description and opens up a novel route to the study of the relation between non-equilibrium dynamics, thermalization and the making and breaking of integrability in quantum many-body physics. Supported by FOM, NWO and EU

  6. Note on a tetrad composed of a two-component spinor and a time-like vector

    International Nuclear Information System (INIS)

    In order to describe and extended object in conformity with relativity, it is useful to introduce a tetrad which is composed of four orthonormal vectors and moves in a similar way as the motion of the object. The tetrad is a kind of relativistic generalization of a body fixed triad which is often employed to describe the non-relativistic motion of a rigid body. In this paper, the study of a tetrad constructed in terms of a two-component spinor and a time-like vector is presented. Three vectors orthogonal to P sub(μ), which is a time-like four-momentum of a closed system, are defined in terms of a two-component spinor Xi sub(α). With a conjugate spinor sup(α) various variables and operators can be introduced, and constraints are described. By using the transformation introduced in this study, the Poincare generators can be rewritten. (Kato, T.)

  7. Interference of Two-Component Bose-Einstein Condensates with a Coupling Drive in Presence of Dissipation

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The interference of the two-component Bose-Einstein condensates with a coupling drive in the presence of the dissipation is studied. We find that when the two-component Bose-Einstein condensates are initially in the coherent states, for the smaller dissipation parameters compared with that of the rf frequency ωrf, the interference intensity exhibits damply oscillation behavior, whereas when the dissipation parameters are larger than that of the ωrf, the interference intensity exhibits a fast attenuation behavior. As a comparison, the interference intensity in the absence of the dissipation is also studied. We conclude that the dissipation of the system can be evaluated by selecting the ωrf experimentally.

  8. Energy spectra of small two-component Fermi gases in a cubic box with periodic boundary conditions

    Science.gov (United States)

    Yin, X. Y.; Blume, D.

    2013-05-01

    The properties of two-component Fermi gases become universal if the interspecies s-wave scattering length and the average interparticle spacing are much larger than the range of the underlying two-body potential. Using an explicitly correlated Gaussian basis set expansion approach, we determine the eigenenergies of two-component Fermi gases in a cubic box with periodic boundary conditions as functions of the interspecies s-wave scattering length and the effective range of the two-body potential. The universal properties of systems consisting of up to five particles are determined by extrapolating the finite-range energies to the zero-range limit. We determine the eigenenergies of states with vanishing and finite momentum. For the infinitely large scattering length case, we compare our results with those presented in the literature. Support by the ARO is gratefully acknowledged.

  9. Stenotrophomonas maltophilia PhoP, a Two-Component Response Regulator, Involved in Antimicrobial Susceptibilities.

    Directory of Open Access Journals (Sweden)

    Ming-Che Liu

    Full Text Available Stenotrophomonas maltophilia, a gram-negative bacterium, has increasingly emerged as an important nosocomial pathogen. It is well-known for resistance to a variety of antimicrobial agents including cationic antimicrobial polypeptides (CAPs. Resistance to polymyxin B, a kind of CAPs, is known to be controlled by the two-component system PhoPQ. To unravel the role of PhoPQ in polymyxin B resistance of S. maltophilia, a phoP mutant was constructed. We found MICs of polymyxin B, chloramphenicol, ampicillin, gentamicin, kanamycin, streptomycin and spectinomycin decreased 2-64 fold in the phoP mutant. Complementation of the phoP mutant by the wild-type phoP gene restored all of the MICs to the wild type levels. Expression of PhoP was shown to be autoregulated and responsive to Mg2+ levels. The polymyxin B and gentamicin killing tests indicated that pretreatment of low Mg2+ can protect the wild-type S. maltophilia from killing but not phoP mutant. Interestingly, we found phoP mutant had a decrease in expression of SmeZ, an efflux transporter protein for aminoglycosides in S. maltophilia. Moreover, phoP mutant showed increased permeability in the cell membrane relative to the wild-type. In summary, we demonstrated the two-component regulator PhoP of S. maltophilia is involved in antimicrobial susceptibilities and low Mg2+ serves as a signal for triggering the pathway. Both the alteration in membrane permeability and downregulation of SmeZ efflux transporter in the phoP mutant contributed to the increased drug susceptibilities of S. maltophilia, in particular for aminoglycosides. This is the first report to describe the role of the Mg2+-sensing PhoP signaling pathway of S. maltophilia in regulation of the SmeZ efflux transporter and in antimicrobial susceptibilities. This study suggests PhoPQ TCS may serve as a target for development of antimicrobial agents against multidrug-resistant S. maltophilia.

  10. Stenotrophomonas maltophilia PhoP, a Two-Component Response Regulator, Involved in Antimicrobial Susceptibilities

    Science.gov (United States)

    Huang, Yi-Wei; Chen, Hsing-Yu; Hsueh, Po-Ren; Lai, Szu-Yu; Chen, Li-Chia; Chou, Yi-Hwa; Lin, Wen-Yuan; Liaw, Shwu-Jen

    2016-01-01

    Stenotrophomonas maltophilia, a gram-negative bacterium, has increasingly emerged as an important nosocomial pathogen. It is well-known for resistance to a variety of antimicrobial agents including cationic antimicrobial polypeptides (CAPs). Resistance to polymyxin B, a kind of CAPs, is known to be controlled by the two-component system PhoPQ. To unravel the role of PhoPQ in polymyxin B resistance of S. maltophilia, a phoP mutant was constructed. We found MICs of polymyxin B, chloramphenicol, ampicillin, gentamicin, kanamycin, streptomycin and spectinomycin decreased 2–64 fold in the phoP mutant. Complementation of the phoP mutant by the wild-type phoP gene restored all of the MICs to the wild type levels. Expression of PhoP was shown to be autoregulated and responsive to Mg2+ levels. The polymyxin B and gentamicin killing tests indicated that pretreatment of low Mg2+ can protect the wild-type S. maltophilia from killing but not phoP mutant. Interestingly, we found phoP mutant had a decrease in expression of SmeZ, an efflux transporter protein for aminoglycosides in S. maltophilia. Moreover, phoP mutant showed increased permeability in the cell membrane relative to the wild-type. In summary, we demonstrated the two-component regulator PhoP of S. maltophilia is involved in antimicrobial susceptibilities and low Mg2+ serves as a signal for triggering the pathway. Both the alteration in membrane permeability and downregulation of SmeZ efflux transporter in the phoP mutant contributed to the increased drug susceptibilities of S. maltophilia, in particular for aminoglycosides. This is the first report to describe the role of the Mg2+-sensing PhoP signaling pathway of S. maltophilia in regulation of the SmeZ efflux transporter and in antimicrobial susceptibilities. This study suggests PhoPQ TCS may serve as a target for development of antimicrobial agents against multidrug-resistant S. maltophilia. PMID:27159404

  11. Stenotrophomonas maltophilia PhoP, a Two-Component Response Regulator, Involved in Antimicrobial Susceptibilities.

    Science.gov (United States)

    Liu, Ming-Che; Tsai, Yi-Lin; Huang, Yi-Wei; Chen, Hsing-Yu; Hsueh, Po-Ren; Lai, Szu-Yu; Chen, Li-Chia; Chou, Yi-Hwa; Lin, Wen-Yuan; Liaw, Shwu-Jen

    2016-01-01

    Stenotrophomonas maltophilia, a gram-negative bacterium, has increasingly emerged as an important nosocomial pathogen. It is well-known for resistance to a variety of antimicrobial agents including cationic antimicrobial polypeptides (CAPs). Resistance to polymyxin B, a kind of CAPs, is known to be controlled by the two-component system PhoPQ. To unravel the role of PhoPQ in polymyxin B resistance of S. maltophilia, a phoP mutant was constructed. We found MICs of polymyxin B, chloramphenicol, ampicillin, gentamicin, kanamycin, streptomycin and spectinomycin decreased 2-64 fold in the phoP mutant. Complementation of the phoP mutant by the wild-type phoP gene restored all of the MICs to the wild type levels. Expression of PhoP was shown to be autoregulated and responsive to Mg2+ levels. The polymyxin B and gentamicin killing tests indicated that pretreatment of low Mg2+ can protect the wild-type S. maltophilia from killing but not phoP mutant. Interestingly, we found phoP mutant had a decrease in expression of SmeZ, an efflux transporter protein for aminoglycosides in S. maltophilia. Moreover, phoP mutant showed increased permeability in the cell membrane relative to the wild-type. In summary, we demonstrated the two-component regulator PhoP of S. maltophilia is involved in antimicrobial susceptibilities and low Mg2+ serves as a signal for triggering the pathway. Both the alteration in membrane permeability and downregulation of SmeZ efflux transporter in the phoP mutant contributed to the increased drug susceptibilities of S. maltophilia, in particular for aminoglycosides. This is the first report to describe the role of the Mg2+-sensing PhoP signaling pathway of S. maltophilia in regulation of the SmeZ efflux transporter and in antimicrobial susceptibilities. This study suggests PhoPQ TCS may serve as a target for development of antimicrobial agents against multidrug-resistant S. maltophilia. PMID:27159404

  12. Dynamics of coupled simplest chaotic two-component electronic circuits and its potential application to random bit generation

    Energy Technology Data Exchange (ETDEWEB)

    Modeste Nguimdo, Romain, E-mail: Romain.Nguimdo@vub.ac.be [Applied Physics Research Group, APHY, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel (Belgium); Tchitnga, Robert [Laboratory of Electronics, Automation and Signal Processing, Department of Physics, University of Dschang, P.O. Box 67, Dschang (Cameroon); Woafo, Paul [Laboratory of Modelling and Simulation in Engineering and Biological Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé (Cameroon)

    2013-12-15

    We numerically investigate the possibility of using a coupling to increase the complexity in simplest chaotic two-component electronic circuits operating at high frequency. We subsequently show that complex behaviors generated in such coupled systems, together with the post-processing are suitable for generating bit-streams which pass all the NIST tests for randomness. The electronic circuit is built up by unidirectionally coupling three two-component (one active and one passive) oscillators in a ring configuration through resistances. It turns out that, with such a coupling, high chaotic signals can be obtained. By extracting points at fixed interval of 10 ns (corresponding to a bit rate of 100 Mb/s) on such chaotic signals, each point being simultaneously converted in 16-bits (or 8-bits), we find that the binary sequence constructed by including the 10(or 2) least significant bits pass statistical tests of randomness, meaning that bit-streams with random properties can be achieved with an overall bit rate up to 10×100 Mb/s =1Gbit/s (or 2×100 Mb/s =200 Megabit/s). Moreover, by varying the bias voltages, we also investigate the parameter range for which more complex signals can be obtained. Besides being simple to implement, the two-component electronic circuit setup is very cheap as compared to optical and electro-optical systems.

  13. Systematic dissection and trajectory-scanning mutagenesis of the molecular interface that ensures specificity of two-component signaling pathways.

    Directory of Open Access Journals (Sweden)

    Emily J Capra

    2010-11-01

    Full Text Available Two-component signal transduction systems enable bacteria to sense and respond to a wide range of environmental stimuli. Sensor histidine kinases transmit signals to their cognate response regulators via phosphorylation. The faithful transmission of information through two-component pathways and the avoidance of unwanted cross-talk require exquisite specificity of histidine kinase-response regulator interactions to ensure that cells mount the appropriate response to external signals. To identify putative specificity-determining residues, we have analyzed amino acid coevolution in two-component proteins and identified a set of residues that can be used to rationally rewire a model signaling pathway, EnvZ-OmpR. To explore how a relatively small set of residues can dictate partner selectivity, we combined alanine-scanning mutagenesis with an approach we call trajectory-scanning mutagenesis, in which all mutational intermediates between the specificity residues of EnvZ and another kinase, RstB, were systematically examined for phosphotransfer specificity. The same approach was used for the response regulators OmpR and RstA. Collectively, the results begin to reveal the molecular mechanism by which a small set of amino acids enables an individual kinase to discriminate amongst a large set of highly-related response regulators and vice versa. Our results also suggest that the mutational trajectories taken by two-component signaling proteins following gene or pathway duplication may be constrained and subject to differential selective pressures. Only some trajectories allow both the maintenance of phosphotransfer and the avoidance of unwanted cross-talk.

  14. Two components in charged particle production in heavy-ion collisions

    Science.gov (United States)

    Bylinkin, A. A.; Chernyavskaya, N. S.; Rostovtsev, A. A.

    2016-02-01

    Transverse momentum spectra of charged particle production in heavy-ion collisions are considered in terms of a recently introduced Two Component parameterization combining exponential ("soft") and power-law ("hard") functional forms. The charged hadron densities calculated separately for them are plotted versus number of participating nucleons, Npart. The obtained dependences are discussed and the possible link between the two component parameterization introduced by the authors and the two component model historically used for the case of heavy-ion collisions is established. Next, the variations of the parameters of the introduced approach with the center of mass energy and centrality are studied using the available data from RHIC and LHC experiments. The spectra shapes are found to show universal dependences on Npart for all investigated collision energies.

  15. MODELING THERMAL DUST EMISSION WITH TWO COMPONENTS: APPLICATION TO THE PLANCK HIGH FREQUENCY INSTRUMENT MAPS

    International Nuclear Information System (INIS)

    We apply the Finkbeiner et al. two-component thermal dust emission model to the Planck High Frequency Instrument maps. This parameterization of the far-infrared dust spectrum as the sum of two modified blackbodies (MBBs) serves as an important alternative to the commonly adopted single-MBB dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. based on FIRAS and DIRBE. We also derive full-sky 6.'1 resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 μm data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.'1 FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to 3000 GHz. We find that, in diffuse sky regions, our two-component 100-217 GHz predictions are on average accurate to within 2.2%, while extrapolating the Planck Collaboration et al. single-MBB model systematically underpredicts emission by 18.8% at 100 GHz, 12.6% at 143 GHz, and 7.9% at 217 GHz. We calibrate our two-component optical depth to reddening, and compare with reddening estimates based on stellar spectra. We find the dominant systematic problems in our temperature/reddening maps to be zodiacal light on large angular scales and the cosmic infrared background anisotropy on small angular scales

  16. Generating ring dark solitons in two-component Bose–Einstein condensates

    International Nuclear Information System (INIS)

    The dynamical evolution of two-component Bose–Einstein condensates trapped in cylindrical well is numerically investigated by solving the coupled Gross–Pitaevskii equations. We illustrate that, due to intercomponent interaction and different initial component populations (n12), different numbers of ring dark (gray) solitons are generated in two components at same time. These solitons have density zeros (minima) accompanied with phase jumps, which cause large superfluid velocities. We also illustrate that at phase jump points ring dark solitons have zero superfluid currents, while ring gray solitons have large superfluid currents. They are unstable and will evolve into other soliton states after a brief time.

  17. Small two-component Fermi gases in a cubic box with periodic boundary conditions

    OpenAIRE

    Yin, X. Y.; Blume, D.

    2013-01-01

    The properties of two-component Fermi gases become universal if the interspecies s-wave scattering length $a_s$ and the average interparticle spacing are much larger than the range of the underlying two-body potential. Using an explicitly correlated Gaussian basis set expansion approach, we determine the eigen energies of two-component Fermi gases in a cubic box with periodic boundary conditions as functions of the interspecies s-wave scattering length and the effective range of the two-body ...

  18. Rabi Oscillations in Two-Component Bose-Einstein Condensates with a Coupling Drive

    Institute of Scientific and Technical Information of China (English)

    LI Wei-Dong; FAN Wen-Bing; ZHOU Xiao-Ji; WANG Yi-Qiu; LIANG Jiu-Qing

    2002-01-01

    The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studiedby means of a pair of bosonic operators. The coupling drive and initial phase difference will affect the amplitudeand the period of the Rabi oscillations. The Rabi oscillations will vanish in the evolution of the condensate densityfor some special initial phase differences (ψ = 0 or π). Our theory provides not only an analytical framework forquantitative predictions for two-component condensates, but also gives an intuitive understanding of some mysteriousfeatures observed in experiments and numerical. simulations.

  19. Low temperatures shear viscosity of a two-component dipolar Fermi gas with unequal population

    Science.gov (United States)

    Darsheshdar, E.; Yavari, H.; Zangeneh, Z.

    2016-07-01

    By using the Green's functions method and linear response theory we calculate the shear viscosity of a two-component dipolar Fermi gas with population imbalance (spin polarized) in the low temperatures limit. In the strong-coupling Bose-Einstein condensation (BEC) region where a Feshbach resonance gives rise to tightly bound dimer molecules, a spin-polarized Fermi superfluid reduces to a simple Bose-Fermi mixture of Bose-condensed dimers and the leftover unpaired fermions (atoms). The interactions between dimer-atom, dimer-dimer, and atom-atom take into account to the viscous relaxation time (τη) . By evaluating the self-energies in the ladder approximation we determine the relaxation times due to dimer-atom (τDA) , dimer-dimer (τcDD ,τdDD) , and atom-atom (τAA) interactions. We will show that relaxation rates due to these interactions τDA-1 ,τcDD-1, τdDD-1, and τAA-1 have T2, T4, e - E /kB T (E is the spectrum of the dimer atoms), and T 3 / 2 behavior respectively in the low temperature limit (T → 0) and consequently, the atom-atom interaction plays the dominant role in the shear viscosity in this rang of temperatures. For small polarization (τDA ,τAA ≫τcDD ,τdDD), the low temperatures shear viscosity is determined by contact interaction between dimers and the shear viscosity varies as T-5 which has the same behavior as the viscosity of other superfluid systems such as superfluid neutron stars, and liquid helium.

  20. Comparative genomic analysis of two-component regulatory proteins in Pseudomonas syringae

    Directory of Open Access Journals (Sweden)

    Ussery David W

    2007-10-01

    Full Text Available Abstract Background Pseudomonas syringae is a widespread bacterial plant pathogen, and strains of P. syringae may be assigned to different pathovars based on host specificity among different plant species. The genomes of P. syringae pv. syringae (Psy B728a, pv. tomato (Pto DC3000 and pv. phaseolicola (Pph 1448A have been recently sequenced providing a major resource for comparative genomic analysis. A mechanism commonly found in bacteria for signal transduction is the two-component system (TCS, which typically consists of a sensor histidine kinase (HK and a response regulator (RR. P. syringae requires a complex array of TCS proteins to cope with diverse plant hosts, host responses, and environmental conditions. Results Based on the genomic data, pattern searches with Hidden Markov Model (HMM profiles have been used to identify putative HKs and RRs. The genomes of Psy B728a, Pto DC3000 and Pph 1448A were found to contain a large number of genes encoding TCS proteins, and a core of complete TCS proteins were shared between these genomes: 30 putative TCS clusters, 11 orphan HKs, 33 orphan RRs, and 16 hybrid HKs. A close analysis of the distribution of genes encoding TCS proteins revealed important differences in TCS proteins among the three P. syringae pathovars. Conclusion In this article we present a thorough analysis of the identification and distribution of TCS proteins among the sequenced genomes of P. syringae. We have identified differences in TCS proteins among the three P. syringae pathovars that may contribute to their diverse host ranges and association with plant hosts. The identification and analysis of the repertoire of TCS proteins in the genomes of P. syringae pathovars constitute a basis for future functional genomic studies of the signal transduction pathways in this important bacterial phytopathogen.

  1. Structural studies of the activation of the two component receiver domain NTRC by multidimensional heteronuclear NMR

    Energy Technology Data Exchange (ETDEWEB)

    Nohaile, M J [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1996-05-01

    Multidimensional heteronuclear NMR spectroscopy was used to investigate the N-terminal domain of the transcriptional enhancer NTRC (NiTrogen Regulatory protein C). This domain belongs to the family of receiver domains of two-component regulatory systems involved in signal transduction. Phosphorylation of NTRC at D54 leads to an activated form of the molecule which stimulates transcription of genes involved in nitrogen regulation. Three and four dimensional NMR techniques were used to determine an intermediate resolution structure of the unphosphorylated, inactive form of the N-terminal domain of NTRC. The structure is comprised of five {alpha}-helices and a five-stranded {beta}-sheet in a ({beta}/{alpha}){sub 5} topology. Analysis of the backbone dynamics of NTRC indicate that helix 4 and strand 5 are significantly more flexible than the rest of the secondary structure of the protein and that the loops making up the active site are flexible. The short lifetime of phospho-NTRC hampers the study of this form. However, conditions for determining the resonance assignments and, possibly, the three dimensional structure of phosphorylated NTRC have been obtained. Tentative assignments of the phosphorylated form indicate that the majority of the changes that NTRC experiences upon phosphorylation occur in helix 3, strand 4, helix 4, strand 5, and the loop between strand 5 and helix 5 (the 3445 face of NTRC) as well as near the site of phosphorylation. In order to examine a stable, activated form of the protein, constitutively active mutants of NTRC were investigated.

  2. Incipient flow properties of two-component fine powder mixtures: Changing the flowability of smaller particles

    Science.gov (United States)

    Kojima, Takehiro; Elliott, James A.

    2013-06-01

    Understanding the flow properties of two-component fine powder systems with micrometre-sized constituents is important for the quality control of electrophotographic printing applications such as photocopiers. In previous work, we studied the incipient flow properties of model powder mixtures of large (d50 ˜ 70 μm) and small (d50 ˜ 6-8 μm) particles under a consolidation stress of 2 kPa, and reported that they were strongly related to the properties of the small particles where the volume ratio of small powder (xs) exceeds ˜0.1 [1]. In this follow-up study, we examine the effect of changing the flowability of the smaller components on the structure and flow properties of the binary mixtures. For the smaller particles, we used poly(styrene-co-divinylbenzene) (PS-DVB) microspheres (d50 = 7.84 μm). The particle surfaces were modified by adding silica nanoparticles in order to prepare PS-DVB powders with a range of flowabilities. These were then mixed with glass ballotini (d50 = 71.9 μm), and the flow properties of these mixtures were evaluated using the shear testing technique. The cohesion of the mixtures showed essentially the same trend as reported in [1] in terms of their dependence on xs and was related to the number of contacts between the PS-DVB particles. Also, it was strongly dependent on the cohesion of the PS-DVB powders despite a very small xs (xs DVB powder was similar, it also showed a correlation with the number of contacts between PS-DVB particles.

  3. On bi-Hamiltonian structure of two-component Novikov equation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Nianhua [Department of Mathematics, China University of Mining and Technology, Beijing 100083 (China); Liu, Q.P., E-mail: qpl@cumtb.edu.cn [Department of Mathematics, China University of Mining and Technology, Beijing 100083 (China)

    2013-01-03

    In this Letter, we present a bi-Hamiltonian structure for the two-component Novikov equation. We also show that proper reduction of this bi-Hamiltonian structure leads to the Hamiltonian operators found by Hone and Wang for the Novikov equation.

  4. Two-Component Horizontal Motion Vectors from Scanning Eye-Safe Aerosol Lidar

    OpenAIRE

    Mayor, Shane; Dérian, Pierre; Héas, Patrick; Memin, Etienne

    2011-01-01

    This poster was presented at the 19th Symposium on Boundary Layers and Turbulence, August 2010, Keystone, CO. Session P1.4. Derive the two-component vector motion field from pairs of aerosol backscatter lidar images and compare results with observations from a co-located sonic anemometer. Two methods will be tested: correlations and dense estimation.

  5. Two-component injection moulding simulation of ABS-POM micro structured surfaces

    DEFF Research Database (Denmark)

    Tosello, Guido; Hansen, Hans Nørgaard; Islam, Aminul

    Multi-component micro injection moulding (μIM) processes such as two-component (2k) μIM are the key technologies for the mass fabrication of multi-material micro products. 2k-μIM experiments involving a miniaturized test component with micro features in the sub-mm dimensional range and moulding a...

  6. Kink-Like Wave and Compacton-Like Wave Solutions for a Two-Component Fornberg-Whitham Equation

    Directory of Open Access Journals (Sweden)

    Shaoyong Li

    2014-01-01

    systems, we study a two-component Fornberg-Whitham equation. Two types of bounded traveling wave solutions are found, that is, the kink-like wave and compacton-like wave solutions. The planar graphs of these solutions are simulated by using software Mathematica; meanwhile, two new phenomena are revealed; that is, the periodic wave solution can become the kink-like wave or compacton-like wave solution under some conditions, respectively. Exact implicit or parameter expressions of these solutions are given.

  7. The dynamics of a slider-crank mechanism with an initially curved coupler under two-component parametric resonance

    Science.gov (United States)

    Wang, Yi-Ming

    2005-02-01

    The objective of this paper is to study the dynamics and dynamic instability of a slider-crank mechanism with an initially curved coupler under parametric resonance. An attention is given to the phenomena arising due to initial curvature, geometric imperfection, of a connecting rod and modal interactions produced by the existence of two-component parametric resonance. The two-component parametric resonance can occur, for example, when the fundamental frequency of the flexible part of a slider-crank mechanism is close to one-half of the excitation frequency and simultaneously the difference between the first and the second natural frequencies is near the frequency of excitation. It is known that for the case of one-component parametric resonance, an initially curved connecting rod enlarges the amplitude of fundamental mode of vibration significantly only if the motion is in the vicinity of the secondary region of instability. In other words, the initial curvature of a coupler plays no effects to the fundamental response of the system if the oscillation is near the primary region of instability. However, result of present study shows that under the condition of two-component parametric resonance, unlike the case of one-component parametric resonance, an initially curved linkage can result significant effects to the vibration of the system even if the motion is close to the primary region of instability. In addition, the result also indicates that the growth of small amplitude vibration into large motion regime occurs if vibrations arise near the boundary of stable region.

  8. An efficient implementation of two-component relativistic exact-decoupling methods for large molecules

    CERN Document Server

    Peng, Daoling; Weigend, Florian; Reiher, Markus

    2013-01-01

    We present an efficient algorithm for one- and two-component relativistic exact-decoupling calculations. The spin-orbit coupling was taken into account for the evaluation of relativistically transformed Hamiltonian. The relativistic decoupling transformation has to be evaluated with primitive functions so that the construction of the relativistic one-electron Hamiltonian becomes the bottleneck of the whole calculation for large molecules. We apply our recently developed local DLU scheme [J. Chem. Phys. 136 (2012) 244108] to accelerate this step. With our new implementation two-component relativistic density functional calculations can be performed invoking the resolution-of-identity density-fitting approximation and (Abelian as well as non-Abelian) point group symmetries to accelerate both the exact-decoupling and the two-electron part. The capability of our implementation is illustrated at the example of silver clusters with up to 309 atoms, for which the cohesive energy is calculated and extrapolated to the...

  9. Formation of combined solitons in two-component Bose–Einstein condensates

    International Nuclear Information System (INIS)

    We investigate the combined soliton solutions of two-component Bose–Einstein condensates with external potential. The “phase diagram” is obtained for the formation regions of different combined solitons. Our results show that the intraspecies (interspecies) interaction strengths and the external trapped potential clearly affect the formation of dark-dark, bright-bright, and dark–bright soliton solutions in different regions. Especially, we find that the bright–bright (dark–dark) soliton can exist in the case of both repulsive (attractive) intraspecies interaction strengths in the presence of external potential. This novel phenomenon is completely different from the formation of soliton solution of one-component Bose–Einstein condensates without external potential, and it will be useful for the study of two-component Bose–Einstein condensates. (general)

  10. Atomic Tunneling Effect in Two-Component Bose-Einstein Condensates with a Coupling Drive

    Institute of Scientific and Technical Information of China (English)

    JIAOZhi-Yong; YUZhao-Xian; YANGXin-Jian

    2004-01-01

    In this paper, we have studied the atomic population difference and the atomic tunneling current of two-component Bose-Einstein condensates with a coupling drive. It is found that when the two-component Bose Einstein condensates are initially in the coherent states, the atomic population difference may exhibit the step structure, in which the numbers of the step increase with the decrease of the Rabi frequency and with the increment of the initial phase difference. The atomic population difference may exhibit collapses, and revivals, in which their periods are affected dramatically by the Rabi frequency and the initial phase difference. The atomic tunneling current may exhibit damping oscillation behaviors, and exist the step structure for the time range of 10-10 ~ 10-9 second.

  11. Error Propagation in Equations for Geochemical Modeling of Radiogenic Isotopes in Two-Component Mixing

    Indian Academy of Sciences (India)

    Surendra P Verma

    2000-03-01

    This paper presents error propagation equations for modeling of radiogenic isotopes during mixing of two components or end-members. These equations can be used to estimate errors on an isotopic ratio in the mixture of two components, as a function of the analytical errors or the total errors of geological field sampling and analytical errors. Two typical cases (``Small errors'' and ``Large errors'') are illustrated for mixing of Sr isotopes. Similar examples can be formulated for the other radiogenic isotopic ratios. Actual isotopic data for sediment and basalt samples from the Cocos plate are also included to further illustrate the use of these equations. The isotopic compositions of the predicted mixtures can be used to constrain the origin of magmas in the central part of the Mexican Volcanic Belt. These examples show the need of high quality experimental data for them to be useful in geochemical modeling of magmatic processes.

  12. Interface dynamics of a two-component Bose-Einstein condensate driven by an external force

    OpenAIRE

    Kobyakov, Dmitry; Bychkov, Vitaly; Lundh, Emil; Bezett, Alice; Akkerman, Vyacheslav; Marklund, Mattias

    2011-01-01

    The dynamics of an interface in a two-component Bose-Einstein condensate driven by a spatially uniform time-dependent force is studied. Starting from the Gross-Pitaevskii Lagrangian, the dispersion relation for linear waves and instabilities at the interface is derived by means of a variational approach. A number of diverse dynamical effects for different types of the driving force is demonstrated, which includes the Rayleigh-Taylor instability for a constant force, the Richtmyer-Meshkov inst...

  13. On the spin separation of algebraic two-component relativistic Hamiltonians

    International Nuclear Information System (INIS)

    The separation of the spin-free and spin-dependent terms of a given relativistic Hamiltonian is usually facilitated by the Dirac identity. However, this is no longer possible for the recently developed exact two-component relativistic Hamiltonians derived from the matrix representation of the Dirac equation in a kinetically balanced basis. This stems from the fact that the decoupling matrix does not have an explicit form. To resolve this formal difficulty, we first define the spin-dependent term as the difference between a two-component Hamiltonian corresponding to the full Dirac equation and its one-component counterpart corresponding to the spin-free Dirac equation. The series expansion of the spin-dependent term is then developed in two different ways. One is in the spirit of the Douglas-Kroll-Hess (DKH) transformation and the other is based on the perturbative expansion of a two-component Hamiltonian of fixed structure, either the two-step Barysz-Sadlej-Snijders (BSS) or the one-step exact two-component (X2C) form. The algorithms for constructing arbitrary order terms are proposed for both schemes and their convergence patterns are assessed numerically. Truncating the expansions to finite orders leads naturally to a sequence of novel spin-dependent Hamiltonians. In particular, the order-by-order distinctions among the DKH, BSS, and X2C approaches can nicely be revealed. The well-known Pauli, zeroth-order regular approximation, and DKH1 spin-dependent Hamiltonians can also be recovered naturally by appropriately approximating the decoupling and renormalization matrices. On the practical side, the sf-X2C+so-DKH3 Hamiltonian, together with appropriately constructed generally contracted basis sets, is most promising for accounting for relativistic effects in two steps, first spin-free and then spin-dependent, with the latter applied either perturbatively or variationally.

  14. A two-component generalized extreme value distribution for precipitation frequency analysis

    Czech Academy of Sciences Publication Activity Database

    Rulfová, Zuzana; Buishand, A.; Roth, M.; Kyselý, Jan

    2016-01-01

    Roč. 534, - (2016), s. 659-668. ISSN 0022-1694 R&D Projects: GA ČR(CZ) GA14-18675S Institutional support: RVO:68378289 Keywords : precipitation extremes * two-component extreme value distribution * regional frequency analysis * convective precipitation * stratiform precipitation * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.053, year: 2014 http://www.sciencedirect.com/science/article/pii/S0022169416000500

  15. Ordinary Chondrite Formation from two Components: Implied Connection to Planet Mercury

    OpenAIRE

    Herndon, J. Marvin

    2004-01-01

    Major element fractionation among chondrites has been discussed for decades as ratios relative to Si or Mg. Expressing ratios relative to Fe leads to a new relationship admitting the possibility that ordinary chondrite meteorites are derived from two components: one is a relatively undifferentiated, primitive component, oxidized like the CI or C1 chondrites; the other is a somewhat differentiated, planetary component, with oxidation state like the reduced enstatite chondrites. Such a picture ...

  16. Three-dimensional solitons in two-component Bose—Einstein condensates

    International Nuclear Information System (INIS)

    We investigate a kind of solitons in the two-component Bose—Einstein condensates with axisymmetric configurations in the R2 × S1 space. The corresponding topological structure is referred to as Hopfion. The spin texture differs from the conventional three-dimensional (3D) skyrmion and knot, which is characterized by two homotopy invariants. The stability of the Hopfion is verified numerically by evolving the Gross—Pitaevskii equations in imaginary time. (general)

  17. Relation between Effective Conductivity and Susceptibility of Two -- Component Rhombic Checkerboard

    OpenAIRE

    Fel, Leonid G.; Kaganov, Ilia V.

    2002-01-01

    The heterogeneity of composite leads to the extra charge concentration at the boundaries of different phases that results essentially nonzero effective electric susceptability. The relation between tensors of effective electric susceptability $\\hat\\chi_{ef}$ and effective conductivity $\\hat\\sigma_{ef}$ of the infinite two--dimensional two--component regular composite with rhombic cells structure has been established. The degrees of electric field singularity at corner points of cells are foun...

  18. Magnetic Richtmyer-Meshkov instability in a two-component Bose-Einstein condensate

    OpenAIRE

    Bezett, Alice; Bychkov, Vitaly; Lundh, Emil; Kobyakov, Dmitry; Marklund, Mattias

    2010-01-01

    The magnetically induced Richtmyer-Meshkov instability in a two-component Bose-Einstein condensate is investigated. We construct and study analytical models describing the development of the instability at both the linear and nonlinear stages. The models indicate new features of the instability: the influence of quantum capillary waves and the separation of droplets, which are qualitatively different from the classical case. We perform numerical simulations of the instability in a trapped Bos...

  19. Stability properties of vector solitons in two-component Bose—Einstein condensates with tunable interactions

    International Nuclear Information System (INIS)

    By using a unified theory of the formation of various types of vector-solitons in two-component Bose—Einstein condensates with tunable interactions, we obtain a family of exact vector-soliton solutions for the coupled nonlinear Schrödinger equations. Moreover, the Bogoliubov equation shows that there exists stable dark soliton in specific situations. Our results open up new ways in considerable experimental interest for the quantum control of multi-component Bose—Einstein condensates. (general)

  20. Composite structure of vortices in two-component Bose-Einstein condensate

    OpenAIRE

    Ivashin Anatoly P.; Poluektov Yuri M.

    2015-01-01

    In contrast to one-component Bose-Einstein condensate case, the vortices in two-component condensate can have various complicated structures. The vortices in a space-homogeneous Bose-Einstein condensate have been studied in this paper. It is shown that the vortex structure is described by three dimensionless parameters. This is totally different from the usual one-component condensate case,where an isolated vortex is described by a parameterless dimensionless equation....

  1. Nontopological vortex in a two-component Bose-Einstein condensate

    International Nuclear Information System (INIS)

    We present a systematic study on a class of stable vortex solutions in a two-component Bose-Einstein condensate. They are nontopological in nature and possess continuous angular momenta. When coupled to external fields, nontopological vortices exhibit 'spin' dynamical behavior and develop a Berry's phase under the adiabatic change of external fields which can be directly measured. We explain a method to create them experimentally by using phase imprinting

  2. Multicomponent radiatively driven stellar winds III. Radiative-acoustic waves in a two-component wind

    OpenAIRE

    Krticka, Jiri; Kubat, Jiri

    2002-01-01

    We study stability of isothermal two-component radiatively driven stellar winds against one-dimensional perturbations larger than the Sobolev length, and radiative-acoustic waves in such stellar winds. We perform linear perturbation analysis in comoving fluid-frames of individual components and obtain dispersion relation in the common fluid-frame. For high density winds the velocity difference between velocities of both components is relatively small and the wind is stable for radiative-acous...

  3. On the spin separation of algebraic two-component relativistic Hamiltonians.

    Science.gov (United States)

    Li, Zhendong; Xiao, Yunlong; Liu, Wenjian

    2012-10-21

    The separation of the spin-free and spin-dependent terms of a given relativistic Hamiltonian is usually facilitated by the Dirac identity. However, this is no longer possible for the recently developed exact two-component relativistic Hamiltonians derived from the matrix representation of the Dirac equation in a kinetically balanced basis. This stems from the fact that the decoupling matrix does not have an explicit form. To resolve this formal difficulty, we first define the spin-dependent term as the difference between a two-component Hamiltonian corresponding to the full Dirac equation and its one-component counterpart corresponding to the spin-free Dirac equation. The series expansion of the spin-dependent term is then developed in two different ways. One is in the spirit of the Douglas-Kroll-Hess (DKH) transformation and the other is based on the perturbative expansion of a two-component Hamiltonian of fixed structure, either the two-step Barysz-Sadlej-Snijders (BSS) or the one-step exact two-component (X2C) form. The algorithms for constructing arbitrary order terms are proposed for both schemes and their convergence patterns are assessed numerically. Truncating the expansions to finite orders leads naturally to a sequence of novel spin-dependent Hamiltonians. In particular, the order-by-order distinctions among the DKH, BSS, and X2C approaches can nicely be revealed. The well-known Pauli, zeroth-order regular approximation, and DKH1 spin-dependent Hamiltonians can also be recovered naturally by appropriately approximating the decoupling and renormalization matrices. On the practical side, the sf-X2C+so-DKH3 Hamiltonian, together with appropriately constructed generally contracted basis sets, is most promising for accounting for relativistic effects in two steps, first spin-free and then spin-dependent, with the latter applied either perturbatively or variationally. PMID:23083155

  4. A Possible Two-Component Structure of the Non-Perturbative Pomeron

    OpenAIRE

    Gauron, Pierre; Nicolescu, Basarab

    2000-01-01

    We propose a QCD-inspired two-component Pomeron form which gives an excellent description of the proton-proton, pi-proton, kaon-proton, gamma-proton and gamma-gamma total cross sections. Our fit has a better CHI2/dof for a smaller number of parameters as compared with the PDG fit. Our 2-Pomeron form is fully compatible with weak Regge exchange-degeneracy, universality, Regge factorization and the generalized vector dominance model.

  5. Two-component model of the interaction of an interstellar cloud with surrounding hot plasma

    OpenAIRE

    Provornikova, E. A.; Izmodenov, V. V.; Lallement, R.

    2011-01-01

    We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma...

  6. Quantum phase transition and engineering in two-component BEC in optical lattices

    OpenAIRE

    Wu, Yong-Shi

    2003-01-01

    In this paper we review recent progress in studying quantum phase transitions in one- and two-component Bose-Einstein condensates (BEC) in optical lattices. These phase transitions involve the emergence and disappearance of quantum coherence over whole optical lattice and of linear superposition of macroscopic quantum states. The latter may provide new means to engineer and to manipulate novel macroscopic quantum states and novel coherent atomic beams for quantum information processing, quant...

  7. Cusp catastrophe of symmetry breaking in two-component Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Bifurcation analysis is applied to the spontaneous spatial symmetry breaking occurring in the ground state of two-component Bose-Einstein condensates. The cusp catastrophe describing the supercritical pitchfork bifurcation associated with the symmetry breaking is derived via the identification of the local curvature of the Gross-Pitaevskii energy functional. The bifurcation diagram and universal scaling laws for the eigenvalue and energy are obtained from the catastrophe function

  8. Sub classification and targeted characterization of prophage-encoded two-component cell lysis cassette

    Indian Academy of Sciences (India)

    K V Srividhya; S Krishnaswamy

    2007-08-01

    Bacteriophage induced lysis of host bacterial cell is mediated by a two component cell lysis cassette comprised of holin and lysozyme. Prophages are integrated forms of bacteriophages in bacterial genomes providing a repertoire for bacterial evolution. Analysis using the prophage database (http://bicmku.in:8082) constructed by us showed 47 prophages were associated with putative two component cell lysis genes. These proteins cluster into four different subgroups. In this process, a putative holin (essd) and endolysin (ybcS), encoded by the defective lambdoid prophage DLP12 was found to be similar to two component cell lysis genes in functional bacteriophages like p21 and P1. The holin essd was found to have a characteristic dual start motif with two transmembrane regions and C-terminal charged residues as in class II holins. Expression of a fusion construct of essd in Escherichia coli showed slow growth. However, under appropriate conditions, this protein could be over expressed and purified for structure function studies. The second component of the cell lysis cassette, ybcS, was found to have an N-terminal SAR (Signal Arrest Release) transmembrane domain. The construct of ybcS has been over expressed in E. coli and the purified protein was functional, exhibiting lytic activity against E. coli and Salmonella typhi cell wall substrate. Such targeted sequence-structure-function characterization of proteins encoded by cryptic prophages will help understand the contribution of prophage proteins to bacterial evolution.

  9. Analytic second derivatives for the spin-free exact two-component theory.

    Science.gov (United States)

    Cheng, Lan; Gauss, Jürgen

    2011-12-28

    The formulation and implementation of the spin-free (SF) exact two-component (X2c) theory at the one-electron level (SFX2c-1e) is extended in the present work to the analytic evaluation of second derivatives of the energy. In the X2c-1e scheme, the four-component one-electron Dirac Hamiltonian is block diagonalized in its matrix representation and the resulting "electrons-only" two-component Hamiltonian is then used together with untransformed two-electron interactions. The derivatives of the two-component Hamiltonian can thus be obtained by means of simple manipulations of the parent four-component Hamiltonian integrals and derivative integrals. The SF version of X2c-1e can furthermore exploit available nonrelativistic quantum-chemical codes in a straightforward manner. As a first application of analytic SFX2c-1e second derivatives, we report a systematic study of the equilibrium geometry and vibrational frequencies for the bent ground state of the copper hydroxide (CuOH) molecule. Scalar-relativistic, electron-correlation, and basis-set effects on these properties are carefully assessed. PMID:22225141

  10. Localized nonlinear vector matter waves in two-component Bose–Einstein condensates with spatially modulated nonlinearities

    International Nuclear Information System (INIS)

    Exact localized nonlinear vector matter waves in the form of soliton–soliton and vortex–vortex pairs in two-component Bose–Einstein condensates with spatially modulated nonlinearity coefficients and harmonic trapping potentials are reported. It is shown that there exists an infinite number of exact vector pairs sharing the same chemical potential with soliton–soliton ones for odd integer n while vortex–vortex ones for even integer n. The stability of the vector pairs found is investigated by means of direct numerical simulations and a linear stability analysis; the results show that the stable vortex–vortex pairs (±l,±l) with large topological charges can be supported by the spatially modulated interaction when the harmonic trapping potential is presented in this system. -- Highlights: ► Exact localized nonlinear vector matter waves in two-component Bose–Einstein condensates with spatially modulated nonlinearities are reported. ► An infinite number of exact vector pairs sharing the same chemical potential are presented. ► The stable vortex–vortex pairs (±l,±l) with large topological charges can be supported in this system.

  11. Vortices in a rotating two-component Bose–Einstein condensate with tunable interactions and harmonic potential

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao-Fei, E-mail: xfzhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); Du, Zhi-Jing [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); Tan, Ren-Bing [Department of Physics, School of Mathematics and Physics, Chongqing University of Science and Technology, Chongqing 401331 (China); Dong, Rui-Fang; Chang, Hong; Zhang, Shou-Gang [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China)

    2014-07-15

    We consider a pair of coupled nonlinear Schrödinger equations modeling a rotating two-component Bose–Einstein condensate with tunable interactions and harmonic potential, with emphasis on the structure of vortex states by varying the strength of inter-component interaction, rotational frequency, and the aspect ratio of the harmonic potential. Our results show that the inter-component interaction greatly enhances the effect of rotation. For the case of isotropic harmonic potential and small inter-component interaction, the initial vortex structure remains unchanged. As the ratio of inter- to intra-component interactions increases, each component undergoes a transition from a vortex lattice (vortex line) in an isotropic (anisotropic) harmonic potential to an alternatively arranged stripe pattern, and eventually to the interwoven “serpentine” vortex sheets. Moreover, in the case of anisotropic harmonic potential the system can develop to a rotating droplet structure. -- Highlights: •Different vortex structures are obtained within the full parameter space. •Effects of system parameters on the ground state structure are discussed. •Phase transition between different vortex structures is also examined. •Present one possible way to obtain the rotating droplet structure. •Provide many possibilities to manipulate vortex in two-component BEC.

  12. Evaluation of the operational parameters for NBI-driven fusion in low-gain tokamaks with two-component plasma

    Science.gov (United States)

    Chirkov, A. Yu.

    2015-09-01

    Low gain (Q ~ 1) fusion plasma systems are of interest for concepts of fusion-fission hybrid reactors. Operational regimes of large modern tokamaks are close to Q  ≈  1. Therefore, they can be considered as prototypes of neutron sources for fusion-fission hybrids. Powerful neutral beam injection (NBI) can support the essential population of fast particles compared with the Maxwellial population. In such two-component plasma, fusion reaction rate is higher than for Maxwellian plasma. Increased reaction rate allows the development of relatively small-size and relatively inexpensive neutron sources. Possible operating regimes of the NBI-heated tokamak neutron source are discussed. In a relatively compact device, the predictions of physics of two-component fusion plasma have some volatility that causes taking into account variations of the operational parameters. Consequent parameter ranges are studied. The feasibility of regimes with Q  ≈  1 is shown for the relatively small and low-power system. The effect of NBI fraction in total heating power is analyzed.

  13. Phase behaviour of two-component bottle-brush polymers with flexible backbones under poor solvent conditions

    International Nuclear Information System (INIS)

    The phase behaviour of two-component bottle-brush polymers with fully flexible backbones under poor solvent conditions is studied via molecular-dynamics simulations, using a coarse-grained bead-spring model and side chains of up to N = 40 effective monomers. We consider a symmetric model where side chains of type A and B are grafted alternately onto a flexible backbone. The aim of this study is to explore the phase behaviour of two-component bottle-brushes depending on parameters, such as as the grafting density σ, the backbone length Nb, the side-chain length N, and the temperature T. Based on a cluster analysis, we identify for our range of parameters the regimes of fully phase separated systems, i.e., A-type side chains form one cluster and B-type chains another, while the interface that separates these two clusters contains the backbone monomers. We find that pearl-necklace or Janus-like structures, which normally occur for bottle-brush polymers with rigid backbones under poor solvent conditions, are fully attributed to the backbone rigidity, and, therefore, such structures are unlikely in the case of bottle brushes with fully flexible backbones. Also, a comparative discussion with earlier work on the phase behaviour of single-component bottle-brush polymers with flexible backbones is performed. (paper)

  14. rgf Encodes a Novel Two-Component Signal Transduction System of Streptococcus agalactiae

    OpenAIRE

    Spellerberg, Barbara; Rozdzinski, Eva; Martin, Simone; Weber-Heynemann, Josefine; Lütticken, Rudolf

    2002-01-01

    The adhesion of gram-positive bacteria to extracellular matrix (ECM) proteins is regarded as an important determinant of pathogenicity. A comparison of the adhesion of Streptococcus agalactiae strain O90R to different ECM proteins showed that the most pronounced binding could be observed for immobilized fibrinogen. To investigate the genetic determinants of S. agalactiae fibrinogen binding, a pGhost9:ISS1 mutant library was screened for mutants displaying reduced agglutination of fibrinogen-c...

  15. Regulation of Virulence by a Two-Component System in Group B Streptococcus†

    OpenAIRE

    Jiang, Sheng-Mei; Cieslewicz, Michael J.; Kasper, Dennis L.; Wessels, Michael R.

    2005-01-01

    Group B Streptococcus (GBS) is frequently carried in the gastrointestinal or genitourinary tract as a commensal organism, yet it has the potential to cause life-threatening infection in newborn infants, pregnant women, and individuals with chronic illness. Regulation of virulence factor expression may affect whether GBS behaves as an asymptomatic colonizer or an invasive pathogen, but little is known about how such factors are controlled in GBS. We now report the characterization of a GBS loc...

  16. Lipase expression in Pseudomonas alcaligenes is under the control of a two-component regulatory system

    NARCIS (Netherlands)

    Krzeslak, Joanna; Gerritse, Gijs; van Merkerk, Ronald; Cool, Robbert H.; Quax, Wim J.

    2008-01-01

    Preliminary observations in a large-scale fermentation process suggested that the lipase expression of Pseudomonas alcaligenes can be switched on by the addition of certain medium components, such as soybean oil. In an attempt to elucidate the mechanism of induction of lipase expression, we have set

  17. Three-body recombination of two-component cold atomic gases into deep dimers in an optical model

    DEFF Research Database (Denmark)

    Mikkelsen, Mathias; Jensen, A. S.; Fedorov, D. V.; Zinner, Nikolaj Thomas

    2015-01-01

    We consider three-body recombination into deep dimers in a mass-imbalanced two-component atomic gas. We use an optical model where a phenomenological imaginary potential is added to the lowest adiabatic hyper-spherical potential. The consequent imaginary part of the energy eigenvalue corresponds to...... the decay rate or recombination probability of the three-body system. The method is formulated in details and the relevant qualitative features are discussed as functions of scattering lengths and masses. We use zero-range model in analyses of recent recombination data. The dominating scattering...... length is usually related to the non-equal two-body systems. We account for temperature smearing which tends to wipe out the higher-lying Efimov peaks. The range and the strength of the imaginary potential determine positions and shapes of the Efimov peaks as well as the absolute value of the...

  18. Numerical simulation of two-component flow fluid - fluid in the microchannel T- type

    Directory of Open Access Journals (Sweden)

    Shebeleva A.A.

    2015-01-01

    Full Text Available Results of testing methodology for calculating two-phase flows based on the method of fluid in the cells (VOF method, and the procedure for CSF accounting of surface tension forces in the microchannel are considered in the work. Mathematical modeling of two-component flow fluid -fluid in the T- microchannel conducted using this methodology. The following flow regimes studied slug flow, rivulet flow, parallel flow, dispersed (droplet flow, plug flow. Comparison of numerical results with experimental data done. Satisfactory agreement between the calculated values with the experimental data obtained.

  19. Optimization and control of two-component radially self-accelerating beams

    International Nuclear Information System (INIS)

    We report on the properties of radially self-accelerating intensity distributions consisting of two components in the angular frequency domain. We show how this subset of solutions, in literature also known as helicon beams, possesses peculiar characteristics that enable a better control over its properties. In this work, we present a step-by-step optimization procedure to achieve the best possible intensity contrast, a distinct rotation rate and long propagation lengths. All points are discussed on a theoretical basis and are experimentally verified

  20. Investigation of the adhesion interface obtained through two-component injection molding

    Science.gov (United States)

    Fetecau, Catalin; Stan, Felicia; Dobrea, Daniel

    2011-01-01

    In this paper we study the interface strength obtained through two-component (2C) injection molding of LDPE-HDPE polymers. First, numerical simulation of the over-molding process is carried out using Moldflow technology. Second, butt-joint specimens were produced by over-molding under different process condition, and tested. Two injection sequences were considered, injection of LDPE on HDPE polymer, and HDLE on LDPE, respectively. To investigate the effects of the mold surface roughness on the polymers adhesion at interface, different inserts with different roughness are employed.

  1. Optimization and control of two-component radially self-accelerating beams

    Energy Technology Data Exchange (ETDEWEB)

    Vetter, Christian; Eichelkraut, Toni; Ornigotti, Marco; Szameit, Alexander [Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Albert-Einstein-Str. 15, 07745 Jena (Germany)

    2015-11-23

    We report on the properties of radially self-accelerating intensity distributions consisting of two components in the angular frequency domain. We show how this subset of solutions, in literature also known as helicon beams, possesses peculiar characteristics that enable a better control over its properties. In this work, we present a step-by-step optimization procedure to achieve the best possible intensity contrast, a distinct rotation rate and long propagation lengths. All points are discussed on a theoretical basis and are experimentally verified.

  2. Three-wave interaction in two-component quadratic nonlinear lattices

    DEFF Research Database (Denmark)

    Konotop, V. V.; Cunha, M. D.; Christiansen, Peter Leth;

    1999-01-01

    We investigate a two-component lattice with a quadratic nonlinearity and find with the multiple scale technique that integrable three-wave interaction takes place between plane wave solutions when these fulfill resonance conditions. We demonstrate that. energy conversion and pulse propagation known...... from three-wave interaction is reproduced in the lattice and that exact phase matching of parametric processes can be obtained in non-phase-matched lattices by tilting the interacting plane waves with respect to each other. [S1063-651X(99)15110-9]....

  3. A new pair of hard-soft plastic combination for precision manufacturing of two component plastic parts.

    OpenAIRE

    Islam, Aminul; Hansen, Hans Nørgaard; Marhöfer, David Maximilian; Bondo, M.

    2011-01-01

    Two component (2k) injection moulding is growing rapidly even in the field of precision micro moulding. Besides combining different material properties in the same product, two component moulding can eliminate many assembly steps in manufacturing process chain. One of the biggest technical challenges associated with 2k moulding is the unavailability of suitable two component material combinations which can meet the diverse requirement from product and process point of view. This paper present...

  4. Two-component vector solitons in defocusing Kerr-type media with spatially modulated nonlinearity

    International Nuclear Information System (INIS)

    We present a class of exact solutions to the coupled (2+1)-dimensional nonlinear Schrödinger equation with spatially modulated nonlinearity and a special external potential, which describe the evolution of two-component vector solitons in defocusing Kerr-type media. We find a robust soliton solution, constructed with the help of Whittaker functions. For specific choices of the topological charge, the radial mode number and the modulation depth, the solitons may exist in various forms, such as the half-moon, necklace-ring, and sawtooth vortex-ring patterns. Our results show that the profile of such solitons can be effectively controlled by the topological charge, the radial mode number, and the modulation depth. - Highlights: • Two-component vector soliton clusters in defocusing Kerr-type media are reported. • These soliton clusters are constructed with the help of Whittaker functions. • The half-moon, necklace-ring and vortex-ring patterns are found. • The profile of these solitons can be effectively controlled by three soliton parameters

  5. Determination of two-dimensional correlation lengths in an anisotropic two-component flow

    International Nuclear Information System (INIS)

    Former studies have shown that correlation methods can be used for determination of various two-component flow parameters, among these the correlation length. In cases where the flow can be described as a mixture, in which the minority component forms spatially limited perturbations within the majority component, this parameter gives a good indication of the maximum extension of these perturbations. In the former studies, spherical symmetry of the perturbations has been assumed, and the correlation length has been measured in the direction of the flow (axially) only. However, if the flow structure is anisotropic, the correlation length will be different in different directions. In the present study, the method has been developed further, allowing also measurements perpendicular to the flow direction (radially). The measurements were carried out using laser beams and the two-component flows consisted of either glass beads and air or air and water. In order to make local measurements of both the axial and radial correlation length simultaneously, it is necessary to use 3 laser beams and to form the triple cross-covariance. This lead to some unforeseen complications, due to the character of this function. The experimental results are generally positive and size determinations with an accuracy of better than 10% have been achieved in most cases. Less accurate results appeared only for difficult conditions (symmetrical signals), when 3 beams were used. 5 refs, 13 figs, 3 tabs

  6. Regularity for 3D Navier-Stokes equations in terms of two components of the vorticity

    Directory of Open Access Journals (Sweden)

    Sadek Gala

    2010-10-01

    Full Text Available We establish regularity conditions for the 3D Navier-Stokes equation via two components of the vorticity vector. It is known that if a Leray-Hopf weak solution $u$ satisfies $$ ilde{omega}in L^{2/(2-r}(0,T;L^{3/r}(mathbb{R}^3quad hbox{with }0two components of the vorticity, $omega =operatorname{curl}u$, then $u$ becomes the classical solution on $(0,T]$ (see [5]. We prove the regularity of Leray-Hopf weak solution $u$ under each of the following two (weaker conditions: $$displaylines{ ilde{omega}in L^{2/(2-r}(0,T;dot {mathcal{M}}_{2, 3/r}(mathbb{R}^3quad hbox{for }0

  7. Modeling and Simulation of Two-Phase Two-Component Flow with Disappearing Nonwetting Phase

    CERN Document Server

    Neumann, Rebecca; Ippisch, Olaf

    2012-01-01

    Carbon Capture and Storage (CCS) is a recently discussed new technology, aimed at allowing an ongoing use of fossil fuels while preventing the produced CO2 to be released to the atmosphere. CSS can be modeled with two components (water and CO2) in two phases (liquid and CO2). To simulate the process, a multiphase flow equation with equilibrium phase exchange is used. One of the big problems arising in two-phase two-component flow simulations is the disappearance of the nonwetting phase, which leads to a degeneration of the equations satisfied by the saturation. A standard choice of primary variables, which is the pressure of one phase and the saturation of the other phase, cannot be applied here. We developed a new approach using the pressure of the nonwetting phase and the capillary pressure as primary variables. One important advantage of this approach is the fact that we have only one set of primary variables that can be used for the biphasic as well as the monophasic case. We implemented this new choice o...

  8. Two-component superconductivity. II. Copper oxide high-Tc superconductors

    International Nuclear Information System (INIS)

    A systematic relationship between the Cu-O-based high-Tc materials and a two-component theory is developed. The two components are mobile-single-particle states associated with Cu-O planes and localized paired (negative-U) states associated with oxygen vacancies. The focus is on identification of the relevant electronic states in theoretical calculations and experimental observations. The family of Cu-O-based materials is discussed and an understanding is developed of the implications of layering and dimensionality, oxygenation, and doping. The relationship to superconducting properties is developed through the pair-density dependence and single-particle-density dependence of superconductivity. Comparisons with existing experimental data are made, distinctive experimental results are predicted. New directions for finding high-Tc materials are suggested both within the Cu-O-based family and in the more general class of materials which share with the Cu-O-based family the structure of metal-semiconductor layering and can be formed with off-stoichiometric compositions

  9. Evidence for Two-Component Jet in Sw J1644+57

    CERN Document Server

    Wang, Jiuzhou; Wang, Dingxiong; Xie, Wei; Zhang, Bing

    2015-01-01

    The continued observations of Sw J1644+57 in X-ray and radio bands accumulated a rich data set to study the relativistic jet launched in this tidal disruption event. We find that the re-brightening feature in the radio light curve can be naturally explained by the two-component jet model. The possible origin of this structured jet are the Blandford-Znajek and Blandford-Payne mechanisms. We also show that this two-component jet model can interpret the two kinds of quasi-periodic variations in the X-ray light curve: a 200 second quasi-periodic oscillation (QPO) and a 2.7-day quasi-periodic variation. The latter is interpreted by a precessing outer jet launched near the Bardeen-Petterson radius of a warped disk. The $\\sim$ 200s QPO could be associated with a second, narrower jet sweeping the observer line-of-sight periodically, which is launched from a spinning black hole in the misaligned direction with respect to the black hole's angular momentum.

  10. An efficient implementation of two-component relativistic exact-decoupling methods for large molecules.

    Science.gov (United States)

    Peng, Daoling; Middendorf, Nils; Weigend, Florian; Reiher, Markus

    2013-05-14

    We present an efficient algorithm for one- and two-component relativistic exact-decoupling calculations. Spin-orbit coupling is thus taken into account for the evaluation of relativistically transformed (one-electron) Hamiltonian. As the relativistic decoupling transformation has to be evaluated with primitive functions, the construction of the relativistic one-electron Hamiltonian becomes the bottleneck of the whole calculation for large molecules. For the established exact-decoupling protocols, a minimal matrix operation count is established and discussed in detail. Furthermore, we apply our recently developed local DLU scheme [D. Peng and M. Reiher, J. Chem. Phys. 136, 244108 (2012)] to accelerate this step. With our new implementation two-component relativistic density functional calculations can be performed invoking the resolution-of-identity density-fitting approximation and (Abelian as well as non-Abelian) point group symmetry to accelerate both the exact-decoupling and the two-electron part. The capability of our implementation is illustrated at the example of silver clusters with up to 309 atoms, for which the cohesive energy is calculated and extrapolated to the bulk. PMID:23676027

  11. Two-component vector solitons in defocusing Kerr-type media with spatially modulated nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Wei-Ping, E-mail: zhongwp6@126.com [Department of Electronic and Information Engineering, Shunde Polytechnic, Guangdong Province, Shunde 528300 (China); Texas A and M University at Qatar, P.O. Box 23874 Doha (Qatar); Belić, Milivoj [Texas A and M University at Qatar, P.O. Box 23874 Doha (Qatar); Institute of Physics, University of Belgrade, P.O. Box 57, 11001 Belgrade (Serbia)

    2014-12-15

    We present a class of exact solutions to the coupled (2+1)-dimensional nonlinear Schrödinger equation with spatially modulated nonlinearity and a special external potential, which describe the evolution of two-component vector solitons in defocusing Kerr-type media. We find a robust soliton solution, constructed with the help of Whittaker functions. For specific choices of the topological charge, the radial mode number and the modulation depth, the solitons may exist in various forms, such as the half-moon, necklace-ring, and sawtooth vortex-ring patterns. Our results show that the profile of such solitons can be effectively controlled by the topological charge, the radial mode number, and the modulation depth. - Highlights: • Two-component vector soliton clusters in defocusing Kerr-type media are reported. • These soliton clusters are constructed with the help of Whittaker functions. • The half-moon, necklace-ring and vortex-ring patterns are found. • The profile of these solitons can be effectively controlled by three soliton parameters.

  12. Numerical analysis of a non equilibrium two-component two-compressible flow in porous media

    KAUST Repository

    Saad, Bilal Mohammed

    2013-09-01

    We propose and analyze a finite volume scheme to simulate a non equilibrium two components (water and hydrogen) two phase flow (liquid and gas) model. In this model, the assumption of local mass non equilibrium is ensured and thus the velocity of the mass exchange between dissolved hydrogen and hydrogen in the gas phase is supposed finite. The proposed finite volume scheme is fully implicit in time together with a phase-by-phase upwind approach in space and it is discretize the equations in their general form with gravity and capillary terms We show that the proposed scheme satisfies the maximum principle for the saturation and the concentration of the dissolved hydrogen. We establish stability results on the velocity of each phase and on the discrete gradient of the concentration. We show the convergence of a subsequence to a weak solution of the continuous equations as the size of the discretization tends to zero. At our knowledge, this is the first convergence result of finite volume scheme in the case of two component two phase compressible flow in several space dimensions.

  13. Analytical energy gradient for the two-component normalized elimination of the small component method

    Science.gov (United States)

    Zou, Wenli; Filatov, Michael; Cremer, Dieter

    2015-06-01

    The analytical gradient for the two-component Normalized Elimination of the Small Component (2c-NESC) method is presented. The 2c-NESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac spin-orbit (SO) splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)]. The effect of spin-orbit coupling (SOC) on molecular geometries is analyzed utilizing the properties of the frontier orbitals and calculated SO couplings. It is shown that bond lengths can either be lengthened or shortened under the impact of SOC where in the first case the influence of low lying excited states with occupied antibonding orbitals plays a role and in the second case the jj-coupling between occupied antibonding and unoccupied bonding orbitals dominates. In general, the effect of SOC on bond lengths is relatively small (≤5% of the scalar relativistic changes in the bond length). However, large effects are found for van der Waals complexes Hg2 and Cn2, which are due to the admixture of more bonding character to the highest occupied spinors.

  14. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model

    Energy Technology Data Exchange (ETDEWEB)

    Butlitsky, M. A.; Zelener, B. V. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Zelener, B. B. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Moscow Engineering Physics Institute, 115409, Russia, Moscow, Kashirskoe sh. 31 (Russian Federation)

    2014-07-14

    A two-component plasma model, which we called a “shelf Coulomb” model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The “shelf Coulomb” model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ε parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ε and γ = βe{sup 2}n{sup 1/3} (where β = 1/k{sub B}T, n is the particle's density, k{sub B} is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ε and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ε{sub crit}≈13(T{sub crit}{sup *}≈0.076),γ{sub crit}≈1.8(v{sub crit}{sup *}≈0.17),P{sub crit}{sup *}≈0.39, where specific volume v* = 1/γ{sup 3} and reduced temperature T{sup *} = ε{sup −1}.

  15. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model.

    Science.gov (United States)

    Butlitsky, M A; Zelener, B B; Zelener, B V

    2014-07-14

    A two-component plasma model, which we called a "shelf Coulomb" model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The "shelf Coulomb" model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ɛ parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ɛ and γ = βe(2)n(1/3) (where β = 1/kBT, n is the particle's density, kB is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ɛ and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ɛ(crit) ≈ 13(T(*)(crit) ≈ 0.076), γ(crit) ≈ 1.8(v(*)(crit) ≈ 0.17), P(*)(crit) ≈ 0.39, where specific volume v* = 1/γ(3) and reduced temperature T(*) = ɛ(-1). PMID:25028031

  16. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model

    International Nuclear Information System (INIS)

    A two-component plasma model, which we called a “shelf Coulomb” model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The “shelf Coulomb” model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ε parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ε and γ = βe2n1/3 (where β = 1/kBT, n is the particle's density, kB is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ε and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of εcrit≈13(Tcrit*≈0.076),γcrit≈1.8(vcrit*≈0.17),Pcrit*≈0.39, where specific volume v* = 1/γ3 and reduced temperature T* = ε−1

  17. Energy Spectrum of Two-Component Bose-Einstein Condensates in Optical Lattices

    Institute of Scientific and Technical Information of China (English)

    HAN Jiu-Rong; LIU Jin-Ming; JING Hui; WANG Yu-Zhu

    2005-01-01

    With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We find that there are two energy bands for each component. The critical condition of the superfluid-Mott insulator phase transition is determined by the energy band structure. We also find that the nearest neighboring and on-site interactions fail to change the structure of energy bands, but shift the energy bands only.According to the conditions of the phase transitions, three stable superfluid and Mott insulating phases can be found by adjusting the experiment parameters. We also discuss the possibility of observing these new phases and their transitions in further experiments.

  18. Two-component mixture model: Application to palm oil and exchange rate

    Science.gov (United States)

    Phoong, Seuk-Yen; Ismail, Mohd Tahir; Hamzah, Firdaus Mohamad

    2014-12-01

    Palm oil is a seed crop which is widely adopt for food and non-food products such as cookie, vegetable oil, cosmetics, household products and others. Palm oil is majority growth in Malaysia and Indonesia. However, the demand for palm oil is getting growth and rapidly running out over the years. This phenomenal cause illegal logging of trees and destroy the natural habitat. Hence, the present paper investigates the relationship between exchange rate and palm oil price in Malaysia by using Maximum Likelihood Estimation via Newton-Raphson algorithm to fit a two components mixture model. Besides, this paper proposes a mixture of normal distribution to accommodate with asymmetry characteristics and platykurtic time series data.

  19. Transfer of orbital angular momentum of light using two component slow light

    CERN Document Server

    Ruseckas, J; Yu, I A; Juzeliunas, G

    2013-01-01

    We study the manipulation of slow light with an orbital angular momentum propagating in a cloud of cold atoms. Atoms are affected by four copropagating control laser beams in a double tripod configuration of the atomic energy levels involved, allowing to minimize the losses at the vortex core of the control beams. In such a situation the atomic medium is transparent for a pair of copropagating probe fields, leading to the creation of two-component (spinor) slow light. We study the interaction between the probe fields when two control beams carry optical vortices of opposite helicity. As a result, a transfer of the optical vortex takes place from the control to the probe fields without switching off and on the control beams. This feature is missing in a single tripod scheme where the optical vortex can be transferred from the control to the probe field only during either the storage or retrieval of light.

  20. Atomic Tunneling Effect in Two-Component Bose-Einstein Condensates with a Coupling Drive

    Institute of Scientific and Technical Information of China (English)

    JIAO Zhi-Yong; YU Zhao-Xian; YANG Xin-Jian

    2004-01-01

    In this paper, we have studied the atomic population difference and the atomic tunneling current of twocomponent Bose-Einstein condensates with a coupling drive. It is found that when the two-component Bose-Einstein condensates are initially in the coherent states, the atomic population difference may exhibit the step structure, in which the numbers of the step increase with the decrease of the Rabi frequency and with the increment of the initial phase difference. The atomic population difference may exhibit collapses, and revivals, in which their periods are affected dramatically by the Rabi frequency and the initial phase difference. The atomic tunneling current may exhibit damping oscillation behaviors, and exist the step structure for the time range of 10-10 ~ 10-9 second.

  1. Evidence of a two-component jet in the afterglow of GRB 070419A

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A two-component jet model is proposed to explain the unusual afterglow of GRB 070419A.Regarding the optical light curve,a wide "jet" with an opening angle of >30-40 degrees is assumed to produce the late shallow decay,while the three early power-law segments must be caused by a narrow jet with an opening angle of-2-4 degrees.Additional energy injections to both components are required.Late X-ray emission may come from either the wide jet or the narrow one.If the latter is correct,the jets may run into an ISM environment and the temporal index of the late energy injection may be q-0.65.

  2. [Acute cholangitis in interstenosis space accompanied by two-component unit of the main bile duct].

    Science.gov (United States)

    Yurchenko, V V

    2016-02-01

    Palliative treatment of obstructive jaundice with the help of biliary endoprosthesis due to the possible complication of post-intervention in the form of insolvency stent deformation or dislocation. The study features in the postoperative period of the main bile duct endoprosthesis about their two-component unit, described the syndrome of the closed space of the bile ducts. On the basis of observation of 14 patients with the given anatomical feature of endoscopic, who were underwent stenting, was assessed frequency of the syndrome and possibilities of its prevention. Interstenosis space expansion of the main bile duct can be a reason for local cholangitis. For the prevention of cholangitis, it should be carried out a separate drainage of interstenosis space with the help of endoprosthesis or by proximal supra-stenotic extension of two or more stents. PMID:27263209

  3. Cloning, purification and characterization of two components of phenol hydroxylase from Rhodococcus erythropolis UPV-1.

    Science.gov (United States)

    Saa, Laura; Jaureguibeitia, Arrate; Largo, Eneko; Llama, María J; Serra, Juan L

    2010-03-01

    Phenol hydroxylase that catalyzes the conversion of phenol to catechol in Rhodococcus erythropolis UPV-1 was identified as a two-component flavin-dependent monooxygenase. The two proteins are encoded by the genes pheA1 and pheA2, located very closely in the genome. The sequenced pheA1 gene was composed of 1,629 bp encoding a protein of 542 amino acids, whereas the pheA2 gene consisted of 570 bp encoding a protein of 189 amino acids. The deduced amino acid sequences of both genes showed high homology with several two-component aromatic hydroxylases. The genes were cloned separately in cells of Escherichia coli M15 as hexahistidine-tagged proteins, and the recombinant proteins His(6)PheA1 and His(6)PheA2 were purified and its catalytic activity characterized. His(6)PheA1 exists as a homotetramer of four identical subunits of 62 kDa that has no phenol hydroxylase activity on its own. His(6)PheA2 is a homodimeric flavin reductase, consisting of two identical subunits of 22 kDa, that uses NAD(P)H in order to reduce flavin adenine dinucleotide (FAD), according to a random sequential kinetic mechanism. The reductase activity was strongly inhibited by thiol-blocking reagents. The hydroxylation of phenol in vitro requires the presence of both His(6)PheA1 and His(6)PheA2 components, in addition to NADH and FAD, but the physical interaction between the proteins is not necessary for the reaction. PMID:19787347

  4. A Two-Component Mixing Model for Predicting Regional Episodic Acidification of Surface Waters During Spring Snowmelt Periods

    Science.gov (United States)

    Eshleman, Keith N.; Davies, Trevor D.; Tranter, Martyn; Wigington, Parker J.

    1995-04-01

    A two-component mixing model of acid neutralizing capacity (ANC) is proposed for explaining two observed features related to the episodic acidification of surface waters during snowmelt periods: (1) maximum episodic declines in ANC are largest in high ANC systems and increase linearly with antecedent ANC and (2) relative depressions in ANC attributable to increases in nitric acid concentrations are larger in low ANC systems, while relative depressions in ANC attributable to dilution of base cations are larger in high ANC systems. Conceptually, the model represents the physical mixing of two hydrochemical end-members within a surface water environment, although the physical sources of water in the model are undefined. The model is shown to explain 55-72% of the total variation of these characteristics among various surface water systems within the Catskill and Adirondack mountain regions of New York. In addition, the model also explains 11-47% of the relative depression in ANC attributable to natural organic acidity in surface waters in these regions. The model is subsequently linked to an empirical equilibrium acidification model for predicting the long-term episodic acidification response of Adirondack lakes during snowmelt periods. Model predictions suggest that percentage decreases in sulfuric acid concentrations of the magnitude mandated by the 1990 Clean Air Act Amendments (40%) will not restore to positive values the ANC of all Adirondack lakes which are currently acidic (ANC nitric acid concentrations may counterbalance the expected increases in ANC attributable to reductions in sulfur deposition.

  5. Miscibility behavior of two-component monolayers at the air-water interface: perfluorocarboxylic acids and DMPE.

    Science.gov (United States)

    Yokoyama, Hiroki; Nakahara, Hiromichi; Nakagawa, Takahiro; Shimono, Satoshi; Sueishi, Kunihiko; Shibata, Osamu

    2009-09-01

    Surface pressure (pi)-molecular area (A) and surface potential (DeltaV)-A isotherms have been measured for two-component monolayers of four different perfluorocarboxylic acids [FCn; perfluorododecanoic acid (FC12), perfluorotetradecanoic acid (FC14), perfluorohexadecanoic acid (FC16), and perfluorooctadecanoic acid (FC18)] and dimyristoylphosphatidylethanolamine (DMPE) on 0.15M NaCl (pH 2) at 298.2K. The present study is focused on the miscibility and the interfacial behavior for the binary DMPE/FCn monolayers upon compression. From the isotherms, the miscibility has been elucidated in terms of the additivity rule, the interaction parameter, and the interaction energy. The interaction parameter (or energy) is compared with that for the previous dipalmitoylphosphatidylcholine (DPPC)/FCn systems [Colloids Surf. B 41 (2005) 285-298] to understand the effect of phospholipids' polar headgroup on the binary miscibility. Furthermore, the phase behavior of the DMPE/FCn systems has been morphologically examined using fluorescence microscopy (FM) and atomic force microscopy (AFM). These images reveal the different interaction modes among the four systems; DMPE can be miscible with FC12 and FC14 and immiscible with FC16 and FC18 in the monolayer state. These systematic examinations indicate that the miscibility of perfluorocarboxylic acids and phospholipids depends on combination of hydrocarbon and fluorocarbon chain lengths and on phospholipids' polar headgroups within a monolayer. PMID:19481762

  6. Devil's crevasse and macroscopic entanglement in two-component Bose-Einstein condensates

    CERN Document Server

    Byrnes, Tim

    2013-01-01

    Spin coherent states are the matter equivalent of optical coherent states, where a large number of two component particles form a macroscopic state displaying quantum coherence. Here we give a detailed study of entanglement generated between two spin-1/2 BECs due to an Sz1 Sz2 interaction. The states that are generated show a remarkably rich structure showing fractal characteristics. In the limit of large particle number N, the entanglement shows a strong dependence upon whether the entangling gate times are a rational or irrational multiple of pi/4. We discuss the robustness of various states under decoherence and show that despite the large number of particles in a typical BEC, entanglement on a macroscopic scale should be observable as long as the gate times are less than hbar/J sqrt[N], where J is the effective BEC-BEC coupling energy. Such states are anticipated to be useful for various quantum information applications such as quantum teleportation and quantum algorithms.

  7. Probing bilayer-cytoskeletal interactions in erythrocytes using a two-component dissipative particle dynamics model

    Science.gov (United States)

    Peng, Zhangli; Li, Xuejin; Pivkin, Igor; Dao, Ming; Karniadakis, George

    2013-11-01

    We develop a two-component dissipative particle dynamics (DPD) model of the red blood cell (RBC) membrane by modeling the lipid bilayer and the cytoskeleton separately. By applying this model to simulate four different experiments on RBCs, including micropipette aspiration, membrane fluctuations, tank-treading motions in shear flow and bilayer tethering in a flow channel, we validated our model and studied the mechanical properties of the bilayer-cytoskeletal interaction in a systematic and controlled manner, such as its elastic stiffness, viscous friction and strength. In the same time, we also resolved several controversies in RBC mechanics, e.g., the dependence of tank-treading frequency on shear rates and the possibility of bilayer-cytoskeletal slip. Furthermore, to investigate RBC dynamics in the microcirculation, we simulated the passages of RBCs through narrow channels of the flow cytometer in vitro and their passages through the splenic inter-endothelial slits in vivo. The effects of RBC geometry and membrane stiffness on the critical pressure gradient of passage were studied, and the simulation results agree well with experimental measurements. This work was supported by National Institutes of Health Grant R01HL094270 and the new Department of Energy Collaboratory on Mathematics for Mesoscopic Modeling of Materials (CM4).

  8. The two-component model of memory development, and its potential implications for educational settings.

    Science.gov (United States)

    Sander, Myriam C; Werkle-Bergner, Markus; Gerjets, Peter; Shing, Yee Lee; Lindenberger, Ulman

    2012-02-15

    We recently introduced a two-component model of the mechanisms underlying age differences in memory functioning across the lifespan. According to this model, memory performance is based on associative and strategic components. The associative component is relatively mature by middle childhood, whereas the strategic component shows a maturational lag and continues to develop until young adulthood. Focusing on work from our own lab, we review studies from the domains of episodic and working memory informed by this model, and discuss their potential implications for educational settings. The episodic memory studies uncover the latent potential of the associative component in childhood by documenting children's ability to greatly improve their memory performance following mnemonic instruction and training. The studies on working memory also point to an immature strategic component in children whose operation is enhanced under supportive conditions. Educational settings may aim at fostering the interplay between associative and strategic components. We explore possible routes towards this goal by linking our findings to recent trends in research on instructional design. PMID:22682913

  9. Accurate design of megadalton-scale two-component icosahedral protein complexes.

    Science.gov (United States)

    Bale, Jacob B; Gonen, Shane; Liu, Yuxi; Sheffler, William; Ellis, Daniel; Thomas, Chantz; Cascio, Duilio; Yeates, Todd O; Gonen, Tamir; King, Neil P; Baker, David

    2016-07-22

    Nature provides many examples of self- and co-assembling protein-based molecular machines, including icosahedral protein cages that serve as scaffolds, enzymes, and compartments for essential biochemical reactions and icosahedral virus capsids, which encapsidate and protect viral genomes and mediate entry into host cells. Inspired by these natural materials, we report the computational design and experimental characterization of co-assembling, two-component, 120-subunit icosahedral protein nanostructures with molecular weights (1.8 to 2.8 megadaltons) and dimensions (24 to 40 nanometers in diameter) comparable to those of small viral capsids. Electron microscopy, small-angle x-ray scattering, and x-ray crystallography show that 10 designs spanning three distinct icosahedral architectures form materials closely matching the design models. In vitro assembly of icosahedral complexes from independently purified components occurs rapidly, at rates comparable to those of viral capsids, and enables controlled packaging of molecular cargo through charge complementarity. The ability to design megadalton-scale materials with atomic-level accuracy and controllable assembly opens the door to a new generation of genetically programmable protein-based molecular machines. PMID:27463675

  10. Modified Baryonic Dynamics: two-component cosmological simulations with light sterile neutrinos

    International Nuclear Information System (INIS)

    In this article we continue to test cosmological models centred on Modified Newtonian Dynamics (MOND) with light sterile neutrinos, which could in principle be a way to solve the fine-tuning problems of the standard model on galaxy scales while preserving successful predictions on larger scales. Due to previous failures of the simple MOND cosmological model, here we test a speculative model where the modified gravitational field is produced only by the baryons and the sterile neutrinos produce a purely Newtonian field (hence Modified Baryonic Dynamics). We use two-component cosmological simulations to separate the baryonic N-body particles from the sterile neutrino ones. The premise is to attenuate the over-production of massive galaxy cluster halos which were prevalent in the original MOND plus light sterile neutrinos scenario. Theoretical issues with such a formulation notwithstanding, the Modified Baryonic Dynamics model fails to produce the correct amplitude for the galaxy cluster mass function for any reasonable value of the primordial power spectrum normalisation

  11. On the spin separation of algebraic two-component relativistic Hamiltonians: Molecular properties

    International Nuclear Information System (INIS)

    The idea for separating the algebraic exact two-component (X2C) relativistic Hamiltonians into spin-free (sf) and spin-dependent terms [Z. Li, Y. Xiao, and W. Liu, J. Chem. Phys. 137, 154114 (2012)] is extended to both electric and magnetic molecular properties. Taking the spin-free terms (which are correct to infinite order in α ≈ 1/137) as zeroth order, the spin-dependent terms can be treated to any desired order via analytic derivative technique. This is further facilitated by unified Sylvester equations for the response of the decoupling and renormalization matrices to single or multiple perturbations. For practical purposes, explicit expressions of order α2 in spin are also given for electric and magnetic properties, as well as two-electron spin-orbit couplings. At this order, the response of the decoupling and renormalization matrices is not required, such that the expressions are very compact and completely parallel to those based on the Breit-Pauli (BP) Hamiltonian. However, the former employ sf-X2C wave functions, whereas the latter can only use nonrelativistic wave functions. As the sf-X2C terms can readily be interfaced with any nonrelativistic program, the implementation of the O(α2) spin-orbit corrections to sf-X2C properties requires only marginal revisions of the routines for evaluating the BP type of corrections

  12. Two-component dipolar Bose-Einstein condensate in concentrically coupled annular traps.

    Science.gov (United States)

    Zhang, Xiao-Fei; Han, Wei; Wen, Lin; Zhang, Peng; Dong, Rui-Fang; Chang, Hong; Zhang, Shou-Gang

    2015-01-01

    Dipolar Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel functional materials. Here we investigate the ground-state and rotational properties of a rotating two-component dipolar Bose-Einstein condensate, which consists of both dipolar bosonic atoms with magnetic dipole moments aligned vertically to the condensate and one without dipole moments, confined in concentrically coupled annular traps. For the nonrotational case, it is found that the tunable dipolar interaction can be used to control the location of each component between the inner and outer rings, and to induce the desired ground-state phase. Under finite rotation, it is shown that there exists a critical value of rotational frequency for the nondipolar case, above which vortex state can form at the trap center, and the related vortex structures depend strongly on the rotational frequency. For the dipolar case, it is found that various ground-state phases and the related vortex structures, such as polygonal vortex clusters and vortex necklaces, can be obtained via a proper choice of the dipolar interaction and rotational frequency. Finally, we also study and discuss the formation process of such vortex structures. PMID:25731962

  13. Gradients for two-component quasirelativistic methods. Application to dihalogenides of element 116.

    Science.gov (United States)

    van Wüllen, Christoph; Langermann, Norbert

    2007-03-21

    The authors report the implementation of geometry gradients for quasirelativistic two-component Hartree-Fock and density functional methods using either the zero-order regular approximation Hamiltonian or spin-dependent effective core potentials. The computational effort of the resulting program is comparable to that of corresponding nonrelativistic calculations, as it is dominated by the evaluation of derivative two-electron integrals, which is the same for both types of calculations. Besides the implementation of derivatives of matrix elements of the one-particle Hamiltonian with respect to nuclear displacements, the calculation of the derivative exchange-correlation energy for the open shell case involves complicated expressions because of the noncollinear approach chosen to define the spin density. A pilot application to dihalogenides of element 116 shows how spin-orbit coupling strongly affects the chemistry of the superheavy p-block elements. While these molecules are bent at a scalar-relativistic level, spin-orbit coupling is so strong that only the 7p3/2 atomic orbitals of element 116 are involved in bonding, which favors linear molecular geometries for dihalogenides with heavy terminal halogen atoms. PMID:17381195

  14. The Formation of Bulges, Discs and Two Component Galaxies in the CANDELS Survey at z < 3

    CERN Document Server

    Margalef-Bentabol, Berta; Mortlock, Alice; Hartley, Will; Duncan, Kenneth; Ferguson, Harry C; Koekemoer, Anton M; Dekel, Avishai; Primack, Joel R

    2016-01-01

    We examine a sample of 1495 galaxies in the CANDELS fields to determine the evolution of two component galaxies, including bulges and discs, within massive galaxies at the epoch 1 < z < 3 when the Hubble sequence forms. We fit all of our galaxies' light profiles with a single S\\'ersic fit, as well as with a combination of exponential and S\\'ersic profiles. The latter is done in order to describe a galaxy with an inner and an outer component, or bulge and disc component. We develop and use three classification methods (visual, F-test and the RFF) to separate our sample into 1-component galaxies (disc/spheroids-like galaxies) and 2-component galaxies (galaxies formed by an 'inner part' or bulge and an 'outer part' or disc). We then compare the results from using these three different ways to classify our galaxies. We find that the fraction of galaxies selected as 2-component galaxies increases on average 50 per cent from the lowest mass bin to the most massive galaxies, and decreases with redshift by a fa...

  15. Modified Baryonic Dynamics: two-component cosmological simulations with light sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Angus, G.W.; Gentile, G. [Department of Physics and Astrophysics, Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium (Belgium); Diaferio, A. [Dipartimento di Fisica, Università di Torino, Via P. Giuria 1, Torino, I-10125 Italy (Italy); Famaey, B. [Observatoire astronomique de Strasbourg, CNRS UMR 7550, Université de Strasbourg, 11 rue de l' Université, Strasbourg, F-67000 France (France); Heyden, K.J. van der, E-mail: garry.angus@vub.ac.be, E-mail: diaferio@ph.unito.it, E-mail: benoit.famaey@astro.unistra.fr, E-mail: gianfranco.gentile@ugent.be, E-mail: heyden@ast.uct.ac.za [Astrophysics, Cosmology and Gravity Centre, Dept. of Astronomy, University of Cape Town, Private Bag X3, Rondebosch, 7701 South Africa (South Africa)

    2014-10-01

    In this article we continue to test cosmological models centred on Modified Newtonian Dynamics (MOND) with light sterile neutrinos, which could in principle be a way to solve the fine-tuning problems of the standard model on galaxy scales while preserving successful predictions on larger scales. Due to previous failures of the simple MOND cosmological model, here we test a speculative model where the modified gravitational field is produced only by the baryons and the sterile neutrinos produce a purely Newtonian field (hence Modified Baryonic Dynamics). We use two-component cosmological simulations to separate the baryonic N-body particles from the sterile neutrino ones. The premise is to attenuate the over-production of massive galaxy cluster halos which were prevalent in the original MOND plus light sterile neutrinos scenario. Theoretical issues with such a formulation notwithstanding, the Modified Baryonic Dynamics model fails to produce the correct amplitude for the galaxy cluster mass function for any reasonable value of the primordial power spectrum normalisation.

  16. Radiative cooling of two-component wire-array Z-pinch plasma

    International Nuclear Information System (INIS)

    Wire-array two-component Z-pinch plasmas containing Al and other elements were studied experimentally and the observations interpreted with the help of theoretical modeling. Special attention was given to achieving reproducible implosions. Cascading implosions in star wire arrays mix components during the implosion phase and implosion dynamics were not affected by changes in concentration. A reduction in Al K-shell radiation and an increase in soft x-ray radiation emission were observed in Al-W plasma with 84% concentration of Al ions compared to only-Al plasma. Plasma with 84% of Al ions has radiative properties like those of W Z-pinches. The analysis of Al K-shell x-ray spectra with a collisional-radiative atomic kinetics model shows a drop of the electron temperature from 400 eV in pure Al plasma to below 300 eV in the Al-W mix. Al-Au Z-pinches present radiation features similar to Al-W plasma. This is indicative of a similar plasma cooling effect due to the presence of a high-Z element

  17. Calibration of the IRD two-component TLD albedo neutron dosemeter in some moderated neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Bruno M.; Silva, Ademir X. da, E-mail: bfreitas@nuclear.ufrj.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Martins, Marcelo M.; Pereira, Walsan W.; Mauricio, Claudia L.P., E-mail: marcelo@ird.gov.br, E-mail: walsan@ird.gov.br, E-mail: claudia@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    In some stray neutron fields, like those found in practices involving the handling of radionuclide sources, the neutron calibration factor for albedo neutron dosemeter can vary widely compared to the factor for bare sources. This is the case for well logging, which is the area with the largest number of workers exposed to neutrons in Brazil. The companies employ routinely {sup 241}Am-Be neutron sources. The albedo response variation is mainly due to the presence of scattered and moderated neutrons. This paper studies the response variation of the two-component TLD albedo neutron dosemeter used in the neutron individual monitoring service of Instituto de Radioprotecao e Dosimetria, in different radionuclide neutron source beams. The neutron spectra were evaluated applying a Bonner sphere spectrometer with a {sup 6}LiI(Eu) detector in the Brazilian National Metrology Neutron Laboratory. Standard neutron sources of {sup 241}Am-Be and {sup 252}Cf were employed, besides {sup 238}Pu-Be. Measurements were also made with scattered and moderated neutron beams, including {sup 252}Cf(D{sub 2}O) reference spectrum, {sup 241}Am-Be moderated with paraffin and silicone and a thermal neutron flux facility. New neutron calibration factors, as a function of the incident to albedo neutron ratio, were proposed for use in the albedo algorithm for occupational fields where the primary neutron beam is one of those studied sources. (author)

  18. Competing interactions in population-imbalanced two-component Bose-Einstein condensates

    Science.gov (United States)

    Galteland, Peder Notto; Sudbø, Asle

    2016-08-01

    We consider a two-component Bose-Einstein condensate with and without synthetic "spin-orbit" interactions in two dimensions. Density and phase fluctuations of the condensate are included, allowing us to study the impact of thermal fluctuations and density-density interactions on the physics originating with spin-orbit interactions. In the absence of spin-orbit interactions, we find that intercomponent density interactions deplete the minority condensate. The thermally driven phase transition is driven by coupled density and phase-fluctuations, but is nevertheless shown to be a phase-transition in the Kosterlitz-Thouless universality class with close to universal amplitude ratios irrespective of whether both the minority- and majority condensates exist in the ground state, or only one condensate exists. In the presence of spin-orbit interactions we observe three separate phases, depending on the strength of the spin-orbit coupling and intercomponent density-density interactions: a phase-modulated phase with uniform amplitudes for small intercomponent interactions, a completely imbalanced, effectively single-component condensate for intermediate spin-orbit coupling strength and sufficiently large intercomponent interactions, and a phase-modulated and amplitude-modulated phase for sufficiently large values of both the spin-orbit coupling and the intercomponent density-density interactions. The phase that is modulated by a single q -vector only is observed to transition into an isotropic liquid through a strong depinning transition with periodic boundary conditions, which weakens with open boundaries.

  19. Calibration of the IRD two-component TLD albedo neutron dosemeter in some moderated neutron fields

    International Nuclear Information System (INIS)

    In some stray neutron fields, like those found in practices involving the handling of radionuclide sources, the neutron calibration factor for albedo neutron dosemeter can vary widely compared to the factor for bare sources. This is the case for well logging, which is the area with the largest number of workers exposed to neutrons in Brazil. The companies employ routinely 241Am-Be neutron sources. The albedo response variation is mainly due to the presence of scattered and moderated neutrons. This paper studies the response variation of the two-component TLD albedo neutron dosemeter used in the neutron individual monitoring service of Instituto de Radioprotecao e Dosimetria, in different radionuclide neutron source beams. The neutron spectra were evaluated applying a Bonner sphere spectrometer with a 6LiI(Eu) detector in the Brazilian National Metrology Neutron Laboratory. Standard neutron sources of 241Am-Be and 252Cf were employed, besides 238Pu-Be. Measurements were also made with scattered and moderated neutron beams, including 252Cf(D2O) reference spectrum, 241Am-Be moderated with paraffin and silicone and a thermal neutron flux facility. New neutron calibration factors, as a function of the incident to albedo neutron ratio, were proposed for use in the albedo algorithm for occupational fields where the primary neutron beam is one of those studied sources. (author)

  20. Analysis of water hammer in two-component two-phase flows

    International Nuclear Information System (INIS)

    The water hammer phenomena caused by a sudden valve closure in air-water two-phase flows must be clarified for the safety analysis of LOCA in reactors and further for the safety of boilers, chemical plants, pipe transport of fluids such as petroleum and natural gas. In the present paper water hammer phenomena caused by a sudden valve closure in two-component two-phase flow are investigated theoretically and experimentally. The phenomena are more complicated that in single phase-flow due to the fact of the presence of compressible component. Basic partial differential equations based on a one-dimensional homogeneous flow model are solved by the method of characteristic. The analysis is extended to include friction in a two-phase mixture depending on the local flow pattern. The profiles of the pressure transients, the propagation velocity of pressure waves and the effect of valve closure on the transient pressure are found. Different two-phase flow pattern and frictional pressure drop correlations were used including Baker, Chesholm and Beggs ampersand Bril correlations

  1. A principle of corresponding states for two-component, self-gravitating fluids

    CERN Document Server

    Caimmi, R

    2009-01-01

    Macrogases are defined as two-component, large-scale celestial objects where the subsystems interact only via gravitation. The macrogas equation of state is formulated and compared to the van der Waals equation of state for ordinary gases. By analogy, it is assumed that real macroisothermal curves in macrogases occur as real isothermal curves in ordinary gases, where a phase transition takes place along a horisontal line in the macrovolume-macropressure (Mv-Mp) plane. A simple guidance case and two density profiles which satisfactorily fit to observations or simulations, are studied in detail. For sufficiently steep density profiles, a critical macroisothermal curve exists as shown by ordinary gases, where the critical point coincides with the horisontal inflexion point. By analogy with ordinary gases, the first quadrant of the (Mv-Mp) plane may be divided into three parts, namely (i) the G region, where only gas exists; (ii) the S region, where only stars exist; (iii) the GS region, where both gas and stars ...

  2. Two-Component Structure in the Entanglement Spectrum of Highly Excited States.

    Science.gov (United States)

    Yang, Zhi-Cheng; Chamon, Claudio; Hamma, Alioscia; Mucciolo, Eduardo R

    2015-12-31

    We study the entanglement spectrum of highly excited eigenstates of two known models that exhibit a many-body localization transition, namely the one-dimensional random-field Heisenberg model and the quantum random energy model. Our results indicate that the entanglement spectrum shows a "two-component" structure: a universal part that is associated with random matrix theory, and a nonuniversal part that is model dependent. The nonuniversal part manifests the deviation of the highly excited eigenstate from a true random state even in the thermalized phase where the eigenstate thermalization hypothesis holds. The fraction of the spectrum containing the universal part decreases as one approaches the critical point and vanishes in the localized phase in the thermodynamic limit. We use the universal part fraction to construct an order parameter for measuring the degree of randomness of a generic highly excited state, which is also a promising candidate for studying the many-body localization transition. Two toy models based on Rokhsar-Kivelson type wave functions are constructed and their entanglement spectra are shown to exhibit the same structure. PMID:26765022

  3. Two-component, ideal, self-gravitating fluids: the fractional virial potential energy

    CERN Document Server

    Caimmi, R

    2008-01-01

    Two-component, ideal, self-gravitating fluids are conceived as macrogases, and the related equation of state is expressed using the virial theorem for subsystems, under the restriction of homeoidally striated density profiles. Shallower density profiles are found to yield an equation of state, \\phi=\\phi(y,m), characterized (for assigned values of the fractional mass, m=M_j/ M_i) by the occurrence of two extremum points, a minimum and a maximum. Steeper density profiles produce a similar equation of state, which implies that a special value of m is related to a critical curve where the above mentioned extremum points reduce to a single horizontal inflexion point, and curves below the critical one show no extremum points. The similarity of the isofractional mass curves to van der Waals' isothermal curves, suggests the possibility of a phase transition in a bell-shaped region of the (O y \\phi) plane, where the fractional truncation radius along a selected direction is y=R_j/R_i, and the fractional virial potenti...

  4. Predictions of phase distribution in liquid-liquid two-component flow using FLUENT

    International Nuclear Information System (INIS)

    Eulerian multiphase model in FLUENT with a one-group interfacial area transport equation (IATE) (named 'FLUENT-IATE model' hereafter) takes into account fluid particle interactions, such as coalescence and disintegration, and therefore is expected to dynamically capture changes in the interfacial structure. In this study, the FLUENT-IATE model was applied to a liquid-liquid two-component vertical flow in a 25-mm inner diameter pipe. The two liquids were immiscible with similar densities, namely water as the continuous phase and Therminol 59 as the dispersed phase, which were used in a ground-based facility to simulate reduced-gravity two-phase flows. This study covered bubbly (drop) flow and bubbly-to-slug flow transition regimes with area-averaged void (drop) fractions from 3 to 30%. Comparisons with the experimental data indicated that for bubbly flows, the predictions of the lateral phase distributions using the FLUENT-IATE model were generally more accurate than those using the model without the IATE. In addition, it was demonstrated that the coalescence of fluid particles was dominated by wake entrainment and enhanced by increasing either the continuous or dispersed phase velocity. However, predictions showed disagreement with experimental data in some flow conditions for larger void fraction conditions, which fell into the bubbly-to-slug flow transition regime and might involve additional fluid particle interaction mechanisms due to the change of flow regimes. (author)

  5. Effects of external magnetic trap on two dark solitons of a two-component Bose-Einstein condensate

    Institute of Scientific and Technical Information of China (English)

    Hong Li; D. N. Wang

    2008-01-01

    Two dark solitons are considered in a two-component Bose-Einstein condensate with an external magnetic trap, and effects of the trap potential on their dynamics are investigated by the numerical simulation. The results show that the dark solitons attract, collide and repel periodically in two components as time changes, the time period depends strictly on the initial condition and the potential, and there are obvious self-trapping effects on the two dark solitons.

  6. Beats and expansion of two-component Bose–Einstein condensates in the Thomas–Fermi limit

    International Nuclear Information System (INIS)

    A unique feature of multi-component Bose–Einstein condensates (BECs) is the possibility of beating frequencies in collective oscillations. We analytically determine this beating frequency for the two-component BEC in one-dimension. We also show that the Thomas–Fermi approximation, where the quantum pressure is neglected, describes well the expansion of the two-component condensate released from an harmonic trap. (paper)

  7. Sequence and Function of LuxU: a Two-Component Phosphorelay Protein That Regulates Quorum Sensing in Vibrio harveyi

    Science.gov (United States)

    Freeman, Jeremy A.; Bassler, Bonnie L.

    1999-01-01

    Vibrio harveyi regulates the expression of bioluminescence (lux) in response to cell density, a phenomenon known as quorum sensing. In V. harveyi, two independent quorum-sensing systems exist, and each produces, detects, and responds to a specific cell density-dependent autoinducer signal. The autoinducers are recognized by two-component hybrid sensor kinases called LuxN and LuxQ, and sensory information from both systems is transduced by a phosphorelay mechanism to the response regulator protein LuxO. Genetic evidence suggests that LuxO-phosphate negatively regulates the expression of luminescence at low cell density in the absence of autoinducers. At high cell density, interaction of the sensors with their cognate autoinducers results in dephosphorylation and inactivation of the LuxO repressor. In the present report, we show that LuxN and LuxQ channel sensory information to LuxO via a newly identified phosphorelay protein that we have named LuxU. LuxU shows sequence similarity to other described phosphorelay proteins, including BvgS, ArcB, and Ypd1. A critical His residue (His 58) of LuxU is required for phosphorelay function. PMID:9922254

  8. Functionalization of PDMS modified and plasma activated two-component polyurethane coatings by surface attachment of enzymes

    International Nuclear Information System (INIS)

    This article describes a new strategy for coupling the enzyme horseradish peroxidase to a two-component polyurethane (2C-PUR) coating. A stable polymer conjugate was achieved by combining the enzyme and the 2C-PUR coating which was modified with poly(dimethylsiloxane) (PDMS), located at the surface. An atmospheric pressure plasma jet system was used to convert alkyl groups from the PDMS into polar silanol functionalities. This conversion was proven by X-ray photoelectron spectroscopy and dynamic contact angle measurements. In addition, the stability of the activated 2C-PUR surface containing silanol groups was determined by measuring the contact angle as a function of time. Compared to the non-modified 2C-PUR systems the one with PDMS displayed a higher stability over a time period over 28 h. In a silanization process the coating was treated with (3-aminopropyl) trimethoxysilane and the enzyme was subsequently immobilized to the coating via the cross linker glutaraldehyde to receive new biomimetic catalytic/enzymatic functions. The chemical immobilization (chemisorption) of the enzyme to the surface showed statistically significant higher biological activity as compared to references samples without using a cross linker (physisorption). The presented technique offers the opportunity to design new and smart multifunctional surface coatings which employ biomimetic capabilities.

  9. The Physarum polycephalum Genome Reveals Extensive Use of Prokaryotic Two-Component and Metazoan-Type Tyrosine Kinase Signaling.

    Science.gov (United States)

    Schaap, Pauline; Barrantes, Israel; Minx, Pat; Sasaki, Narie; Anderson, Roger W; Bénard, Marianne; Biggar, Kyle K; Buchler, Nicolas E; Bundschuh, Ralf; Chen, Xiao; Fronick, Catrina; Fulton, Lucinda; Golderer, Georg; Jahn, Niels; Knoop, Volker; Landweber, Laura F; Maric, Chrystelle; Miller, Dennis; Noegel, Angelika A; Peace, Rob; Pierron, Gérard; Sasaki, Taeko; Schallenberg-Rüdinger, Mareike; Schleicher, Michael; Singh, Reema; Spaller, Thomas; Storey, Kenneth B; Suzuki, Takamasa; Tomlinson, Chad; Tyson, John J; Warren, Wesley C; Werner, Ernst R; Werner-Felmayer, Gabriele; Wilson, Richard K; Winckler, Thomas; Gott, Jonatha M; Glöckner, Gernot; Marwan, Wolfgang

    2016-01-01

    Physarum polycephalum is a well-studied microbial eukaryote with unique experimental attributes relative to other experimental model organisms. It has a sophisticated life cycle with several distinct stages including amoebal, flagellated, and plasmodial cells. It is unusual in switching between open and closed mitosis according to specific life-cycle stages. Here we present the analysis of the genome of this enigmatic and important model organism and compare it with closely related species. The genome is littered with simple and complex repeats and the coding regions are frequently interrupted by introns with a mean size of 100 bases. Complemented with extensive transcriptome data, we define approximately 31,000 gene loci, providing unexpected insights into early eukaryote evolution. We describe extensive use of histidine kinase-based two-component systems and tyrosine kinase signaling, the presence of bacterial and plant type photoreceptors (phytochromes, cryptochrome, and phototropin) and of plant-type pentatricopeptide repeat proteins, as well as metabolic pathways, and a cell cycle control system typically found in more complex eukaryotes. Our analysis characterizes P. polycephalum as a prototypical eukaryote with features attributed to the last common ancestor of Amorphea, that is, the Amoebozoa and Opisthokonts. Specifically, the presence of tyrosine kinases in Acanthamoeba and Physarum as representatives of two distantly related subdivisions of Amoebozoa argues against the later emergence of tyrosine kinase signaling in the opisthokont lineage and also against the acquisition by horizontal gene transfer. PMID:26615215

  10. Study on the effect of one-dimensional natural circulation on the mixing process of two component gases

    International Nuclear Information System (INIS)

    This study is to investigate the effect of one-dimensional natural circulation on the mixing process of two component gases by evaluating the onset time of natural circulation through the apparatus under the stable density stratified fluid layer. The experimental apparatus consists of a reverse U-shaped vertical slot and a storage tank. The left side vertical slot consists of the heated wall and the cooled wall. The right side vertical slot consists of the two cooled walls. Temperature difference between the vertical walls was set to 50, 70, and 100 K. In this study, the combination of the two component gases is He/Ar and density ratio of each component is 1.4/10. These experimental results show that generation time of natural circulation was affected by molecular diffusion and localized natural convection. When the two components of gases have large density ratios and large Gr numbers, the mixing process of two components of gases was affected by more intensively molecular diffusion than localized natural convection when temperature difference was 50 K. The mixing process of two component gas was affected by more intensively localized natural convection than molecular diffusion when temperature difference was 70 to 100 K. However, two component gases were affected by more intensively molecular diffusion than localized natural convection at small density ratios and small Gr numbers. (author)

  11. Perturbative treatment of spin-orbit coupling within spin-free exact two-component theory

    International Nuclear Information System (INIS)

    This work deals with the perturbative treatment of spin-orbit-coupling (SOC) effects within the spin-free exact two-component theory in its one-electron variant (SFX2C-1e). We investigate two schemes for constructing the SFX2C-1e SOC matrix: the SFX2C-1e+SOC [der] scheme defines the SOC matrix elements based on SFX2C-1e analytic-derivative theory, hereby treating the SOC integrals as the perturbation; the SFX2C-1e+SOC [fd] scheme takes the difference between the X2C-1e and SFX2C-1e Hamiltonian matrices as the SOC perturbation. Furthermore, a mean-field approach in the SFX2C-1e framework is formulated and implemented to efficiently include two-electron SOC effects. Systematic approximations to the two-electron SOC integrals are also proposed and carefully assessed. Based on benchmark calculations of the second-order SOC corrections to the energies and electrical properties for a set of diatomic molecules, we show that the SFX2C-1e+SOC [der] scheme performs very well in the computation of perturbative SOC corrections and that the “2eSL” scheme, which neglects the (SS|SS)-type two-electron SOC integrals, is both efficient and accurate. In contrast, the SFX2C-1e+SOC [fd] scheme turns out to be incompatible with a perturbative treatment of SOC effects. Finally, as a first chemical application, we report high-accuracy calculations of the 201Hg quadrupole-coupling parameters of the recently characterized ethylmercury hydride (HHgCH2CH3) molecule based on SFX2C-1e coupled-cluster calculations augmented with second-order SOC corrections obtained at the Hartree-Fock level using the SFX2C-1e+SOC [der]/2eSL scheme

  12. Large-scale Models Reveal the Two-component Mechanics of Striated Muscle

    Directory of Open Access Journals (Sweden)

    Robert Jarosch

    2008-12-01

    Full Text Available This paper provides a comprehensive explanation of striated muscle mechanics and contraction on the basis of filament rotations. Helical proteins, particularly the coiled-coils of tropomyosin, myosin and α-actinin, shorten their H-bonds cooperatively and produce torque and filament rotations when the Coulombic net-charge repulsion of their highly charged side-chains is diminished by interaction with ions. The classical “two-component model” of active muscle differentiated a “contractile component” which stretches the “series elastic component” during force production. The contractile components are the helically shaped thin filaments of muscle that shorten the sarcomeres by clockwise drilling into the myosin cross-bridges with torque decrease (= force-deficit. Muscle stretch means drawing out the thin filament helices off the cross-bridges under passive counterclockwise rotation with torque increase (= stretch activation. Since each thin filament is anchored by four elastic α-actinin Z-filaments (provided with forceregulating sites for Ca2+ binding, the thin filament rotations change the torsional twist of the four Z-filaments as the “series elastic components”. Large scale models simulate the changes of structure and force in the Z-band by the different Z-filament twisting stages A, B, C, D, E, F and G. Stage D corresponds to the isometric state. The basic phenomena of muscle physiology, i. e. latency relaxation, Fenn-effect, the force-velocity relation, the length-tension relation, unexplained energy, shortening heat, the Huxley-Simmons phases, etc. are explained and interpreted with the help of the model experiments.

  13. Analysis of water hammer in two-component two-phase flows

    International Nuclear Information System (INIS)

    The water hammer phenomena caused by a sudden valve closure in air-water two-phase flows must be clarified for the safety analysis of LOCA in reactors and further for the safety of boilers, chemical plants, pipe transport of fluids such as petroleum and natural gas. In the present work water hammer phenomena caused by sudden valve closure in two-component two-phase flows are investigated theoretically and experimentally. The phenomena are more complicated than in single phase-flows due to the fact of the presence of compressible component. Basic partial differential equations based on a one-dimensional homogeneous flow model are solved by the method of characteristic. The analysis is extended to include friction in a two-phase mixture depending on the local flow pattern. The profiles of the pressure transients, the propagation velocity of pressure waves and the effect of valve closure on the transient pressure are found. Different two-phase flow pattern and frictional pressure drop correlations were used including Baker, Chesholm and Beggs and Bril correlations. The effect of the flow pattern on the characteristic of wave propagation is discussed primarily to indicate the effect of void fraction on the velocity of wave propagation and on the attenuation of pressure waves. Transient pressure in the mixture were recorded at different air void fractions, rates of uniform valve closure and liquid flow velocities with the aid of pressure transducers, transient wave form recorders interfaced with an on-line pc computer. The results are compared with computation, and good agreement was obtained within experimental accuracy

  14. Characterization of GX 339-4 outburst of 2010-11: analysis by XSPEC using two component advective flow model

    Science.gov (United States)

    Debnath, Dipak; Mondal, Santanu; Chakrabarti, Sandip K.

    2015-02-01

    We study spectral properties of GX 339-4 during its 2010-11 outburst with two component advective flow (TCAF) model after its inclusion in XSPEC as a table model. We compare results fitted by TCAF model with combined disc blackbody and power-law model. For a spectral fit, we use 2.5-25 keV spectral data of the Proportional Counter Array instrument onboard RXTE satellite. From our fit, accretion flow parameters such as Keplerian (disc) rate, sub-Keplerian (halo) rate, location and strength of shock are extracted. We quantify how the disc and the halo rates vary during the entire outburst. We study how the halo to disc accretion rate ratio (ARR), quasi-periodic oscillations (QPOs), shock locations and its strength vary when the system passes through hard, hard-intermediate, soft-intermediate and soft states. We find pieces of evidence of monotonically increasing and decreasing nature of QPO frequencies depending on the variation of ARR during rising and declining phases. Interestingly, on days of transition from hard state to hard-intermediate spectral state (during the rising phase) or vice-versa (during decline phase), ARR is observed to be locally maximum. Non-constancy of ARR while obtaining reasonable fits points to the presence of two independent components in the flow.

  15. Laplace-transformed atomic orbital-based M{\\o}ller-Plesset perturbation theory for relativistic two-component Hamiltonians

    CERN Document Server

    Helmich-Paris, Benjamin; Visscher, Lucas

    2016-01-01

    We present a formulation of Laplace-transformed atomic orbital-based second-order M{\\o}ller-Plesset perturbation theory (MP2) energies for two-component Hamiltonians in the Kramers-restricted formalism. This low-order scaling technique can be used to enable correlated relativistic calculations for large molecular systems. We show that the working equations to compute the relativistic MP2 energy differ by merely a change of algebra (quaternion instead of real) from their non-relativistic counterparts. With a proof-of-principle implementation we study the effect of the nuclear charge on the magnitude of half-transformed integrals and show that for light elements spin-free and spin-orbit MP2 energies are almost identical. Furthermore, we investigate the effect of separation of charge distributions on the Coulomb and exchange energy con- tributions, which show the same long-range decay with the inter-electronic / atomic distance as for non-relativistic MP2. A linearly scaling implementation is possible if the pro...

  16. MECHANICAL RELAXATION TIME OF A TWO-COMPONENT EPOXY NETWORK-LiClO4 POLYMER ELECTROLYTE

    Institute of Scientific and Technical Information of China (English)

    PENG Xinsheng; WU Shuyun; CHEN Donglin

    1993-01-01

    The mechanical relaxation time of a two-component epoxy network-LiClO4 system as a polymer electrolyte was investigated.The network is composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl ether of glycerol (TGEG),wherein LiClO4 was incorporated and acts as both the ionic carrier and the curing catalyst.As the relaxation time is informative to the segmental mobility,which is known to be essential for ionic conductivity,the average relaxation times of the specimens were determined through master curve construction.Experimental results showed that the salt concentration,molecular weight of PEG in DGEPEG and DGEPEG/TGEG ratio have profound effect on the relaxation time of the specimen.Among these factors,the former reinforces the network hains,leading to lengthen the relaxation time,whereas the latter two are in favour of the chain flexibility and show an opposite effect.The findings was rationalized in terms of the free volume concept.

  17. Laplace-transformed atomic orbital-based Møller-Plesset perturbation theory for relativistic two-component Hamiltonians

    Science.gov (United States)

    Helmich-Paris, Benjamin; Repisky, Michal; Visscher, Lucas

    2016-07-01

    We present a formulation of Laplace-transformed atomic orbital-based second-order Møller-Plesset perturbation theory (MP2) energies for two-component Hamiltonians in the Kramers-restricted formalism. This low-order scaling technique can be used to enable correlated relativistic calculations for large molecular systems. We show that the working equations to compute the relativistic MP2 energy differ by merely a change of algebra (quaternion instead of real) from their non-relativistic counterparts. With a proof-of-principle implementation we study the effect of the nuclear charge on the magnitude of half-transformed integrals and show that for light elements spin-free and spin-orbit MP2 energies are almost identical. Furthermore, we investigate the effect of separation of charge distributions on the Coulomb and exchange energy contributions, which show the same long-range decay with the inter-electronic/atomic distance as for non-relativistic MP2. A linearly scaling implementation is possible if the proper distance behavior is introduced to the quaternion Schwarz-type estimates as for non-relativistic MP2.

  18. Laplace-transformed atomic orbital-based Møller-Plesset perturbation theory for relativistic two-component Hamiltonians.

    Science.gov (United States)

    Helmich-Paris, Benjamin; Repisky, Michal; Visscher, Lucas

    2016-07-01

    We present a formulation of Laplace-transformed atomic orbital-based second-order Møller-Plesset perturbation theory (MP2) energies for two-component Hamiltonians in the Kramers-restricted formalism. This low-order scaling technique can be used to enable correlated relativistic calculations for large molecular systems. We show that the working equations to compute the relativistic MP2 energy differ by merely a change of algebra (quaternion instead of real) from their non-relativistic counterparts. With a proof-of-principle implementation we study the effect of the nuclear charge on the magnitude of half-transformed integrals and show that for light elements spin-free and spin-orbit MP2 energies are almost identical. Furthermore, we investigate the effect of separation of charge distributions on the Coulomb and exchange energy contributions, which show the same long-range decay with the inter-electronic/atomic distance as for non-relativistic MP2. A linearly scaling implementation is possible if the proper distance behavior is introduced to the quaternion Schwarz-type estimates as for non-relativistic MP2. PMID:27394099

  19. Atomic resolution imaging of the two-component Dirac-Landau levels in a gapped graphene monolayer

    Science.gov (United States)

    Wang, Wen-Xiao; Yin, Long-Jing; Qiao, Jia-Bin; Cai, Tuocheng; Li, Si-Yu; Dou, Rui-Fen; Nie, Jia-Cai; Wu, Xiaosong; He, Lin

    2015-10-01

    The wave function of Dirac fermions is a two-component spinor. In graphene, a one-atom-thick film showing two-dimensional Dirac-like electronic excitations, the two-component representation, reflects the amplitude of the electron wave function on the A and B sublattices. This unique property provides unprecedented opportunities to image the two components of Dirac fermions spatially. Here, we report atomic resolution imaging of two-component Dirac-Landau levels in gapped graphene monolayers by scanning tunneling microscopy and spectroscopy. A gap of about 20 meV, driven by inversion symmetry breaking by the substrate potential, is observed in the graphene sheets on both SiC and graphite substrates. Such a gap splits the n =0 Landau level (LL) into two levels, 0+ and 0-. We demonstrate that the amplitude of the wave function of the 0+ LL is mainly on the A sites and that of the 0- LL is mainly on the B sites of graphene, characterizing the internal structure of the spinor of the n =0 LL. This provides direct evidence of the two-component nature of Dirac fermions.

  20. Mixing process by molecular diffusion and natural circulation of two component gases in a reversed U-shaped channel

    International Nuclear Information System (INIS)

    This study is to investigate an effect of natural convection (or natural circulation) on a mixing process by molecular diffusion in a reverse U-shaped channel consisting of two component gases. It is confirmed that these phenomena appear when the depressurization accident occurs in the very high temperature reactor (VHTR). The experiment has been performed regarding the combined phenomena of molecular diffusion and natural circulation in a two parallel vertical slots filled with two component gases. The experimental results show that the transport phenomena by the molecular diffusion are influenced by the natural circulation of the gas mixture in the reverse U-shaped channel. (author)

  1. Experimental investigation of the factors influencing the polymer-polymer bond strength during two component injection moulding

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben

    2007-01-01

    effectively control the adhesion between two polymers. The effects of environmental conditions on the bond strength after moulding are also investigated. The material selections and environmental conditions were chosen based on the suitability of MID production, but the results and discussion presented in......Two component injection moulding is a commercially important manufacturing process and a key technology for Moulded Interconnect Devices (MIDs). Many fascinating applications of two component or multi component polymer parts are restricted due to the weak interfacial adhesion of the polymers. A...

  2. A Principle of Corresponding States for Two-Component, Self-Gravitating Fluids

    Directory of Open Access Journals (Sweden)

    Caimmi, R.

    2010-06-01

    Full Text Available Macrogases are defined as two-component,large-scale celestial objects where the subsystems interact only via gravitation.The macrogas equation of state is formulated and compared to the van der Waals (VDWequation of state for ordinary gases.By analogy, it is assumed that real macroisothermal curves in macrogases occur as real isothermal curves in ordinary gases, where a phase transition(vapour-liquid observed in ordinary gases and gas-stars assumed in macrogases takesplace along a horizontal linein the macrovolume-macropressure{small $({sf O}sX_mathrm{V}sX_mathrm{p}$} plane.The intersections between real and theoretical(deduced from the equation of state macro isothermalcurves, make two regions of equal surface as for ordinary gases obeying the VDW equation of state.A numerical algorithm is developed for determining the following points of a selected theoretical macroisothermal curve on the {small $({sf O}sX_mathrm{V}sX_mathrm{p}$} plane:the three intersections with the related real macroisothermal curve,and the two extremum points (one maximum and one minimum. Different kinds of macrogases are studied in detail: UU, where U density profiles are flat, to be conceived as a simple guidance case; HH, where H density profiles obey the Hernquist (1990 law, which satisfactorily fits the observed spheroidal components of galaxies; HN/NH, where N density profiles obey the Navarro-Frenk-White (1995,1996, 1997 law, which satisfactorily fits the simulated nonbaryonic dark matter haloes.A different trend is shown by theoretical macroisothermal curves on the{small $({sf O}sX_mathrm{V}sX_mathrm{p}$} plane,according to whether density profiles are sufficiently mild (UU or sufficiently steep (HH, HN/NH.In the former alternative, no critical macroisothermal curve exists, below or above which the trend is monotonous. In the latter alternative, a critical macroisothermal curve exists, as shown by VDW gases, where the critical point may be defined as the horizontal

  3. A Principle of Corresponding States for Two-Component, Self-Gravitating Fluids

    Science.gov (United States)

    Caimmi, R.

    2010-06-01

    Macrogases are defined as two-component, large-scale celestial objects where the subsystems interact only via gravitation. The macrogas equation of state is formulated and compared to the van der Waals (VDW) equation of state for ordinary gases. By analogy, it is assumed that real macroisothermal curves in macrogases occur as real isothermal curves in ordinary gases, where a phase transition (vapour-liquid observed in ordinary gases and gas-stars assumed in macrogases) takes place along a horizontal line in the macrovolume-macropressure (O X_{V} X_{p}) plane. The intersections between real and theoretical (deduced from the equation of state) macroisothermal curves, make two regions of equal surface as for ordinary gases obeying the VDW equation of state. A numerical algorithm is developed for determining the following points of a selected theoretical macroisothermal curve on the (O X_{V} X_{p}) plane: the three intersections with the related real macroisothermal curve, and the two extremum points (one maximum and one minimum). Different kinds of macrogases are studied in detail: UU, where U density profiles are flat, to be conceived as a simple guidance case; HH, where H density profiles obey the Hernquist (1990) law, which satisfactorily fits the observed spheroidal components of galaxies; HN/NH, where N density profiles obey the Navarro-Frenk-White (1995, 1996, 1997) law, which satisfactorily fits the simulated nonbaryonic dark matter haloes. A different trend is shown by theoretical macroisothermal curves on the (O X_{V} X_{p}) plane, according to whether density profiles are sufficiently mild (UU) or sufficiently steep (HH, HN/NH). In the former alternative, no critical macroisothermal curve exists, below or above which the trend is monotonous. In the latter alternative, a critical macroisothermal curve exists, as shown by VDW gases, where the critical point may be defined as the horizontal inflexion point. In any case, by analogy with VDW gases, the first

  4. Dynamics involved in catalysis by single-component and two-component flavin-dependent aromatic hydroxylases

    International Nuclear Information System (INIS)

    Flavoprotein monooxygenases are involved in a wide variety of biological processes including drug detoxification, biodegradation of aromatic compounds in the environment, biosynthesis of antibiotics and siderophores, and many others. The reactions use NAD(P)H and O2 as co-substrates and insert one atom of oxygen into the substrate. The flavin-dependent monooxygenases utilize a general cycle in which NAD(P)H reduces the flavin, and the reduced flavin reacts with O2 to form a C4a-(hydro)peroxyflavin intermediate, which is the oxygenating agent. This complicated catalytic process has diverse requirements that are difficult to be satisfied by a single site. Two general strategies have evolved to satisfy these requirements. para-Hydroxybenzoate hydroxylase, the paradigm for the single-component flavoprotein monooxygenases, is one of the most thoroughly studied of all enzymes. This enzyme undergoes significant protein and flavin dynamics during catalysis. There is an open conformation that gives access of substrate and product to solvent, and a closed or in conformation for the reaction with oxygen and the hydroxylation to occur. This closed form prevents solvent from destabilizing the hydroperoxyflavin intermediate. Finally, there is an out conformation achieved by movement of the isoalloxazine toward the solvent, which exposes its N5 for hydride delivery from NAD(P)H. The protein coordinates these dynamic events during catalysis. The second strategy uses a reductase to catalyze the reduction of the flavin and an oxygenase that uses the reduced flavin as a substrate to react with oxygen and hydroxylate the organic substrate. These two-component systems must be able to transfer reduced flavin from the reductase to the oxygenase and stabilize a C4a-peroxyflavin until a substrate binds to be hydroxylated, all before flavin oxidation and release of H2O2. Again, protein dynamics are important for catalytic success

  5. Five new Fast Radio Bursts from the HTRU high latitude survey at Parkes: first evidence for two-component bursts

    Science.gov (United States)

    Champion, D. J.; Petroff, E.; Kramer, M.; Keith, M. J.; Bailes, M.; Barr, E. D.; Bates, S. D.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Flynn, C. M. L.; Jameson, A.; Johnston, S.; Ng, C.; Levin, L.; Possenti, A.; Stappers, B. W.; van Straten, W.; Thornton, D.; Tiburzi, C.; Lyne, A. G.

    2016-04-01

    The detection of five new fast radio bursts (FRBs) found in the 1.4-GHz High Time Resolution Universe high latitude survey at Parkes, is presented. The rate implied is 7^{+5}_{-3}× 10^3 (95%) FRBs sky-1 day-1 above a fluence of 0.13 Jy ms for an FRB of 0.128 ms duration to 1.5 Jy ms for 16 ms duration. One of these FRBs has a two-component profile, in which each component is similar to the known population of single component FRBs and the two components are separated by 2.4 ± 0.4 ms. All the FRB components appear to be unresolved following deconvolution with a scattering tail and accounting for intra-channel smearing. The two-component burst, FRB 121002, also has the highest dispersion measure (1629 pc cm-3) of any FRB to-date. Many of the proposed models to explain FRBs use a single high energy event involving compact objects (such as neutron star mergers) and therefore cannot easily explain a two-component FRB. Models that are based on extreme versions of flaring, pulsing or orbital events however could produce multiple component profiles. The compatibility of these models and the FRB rate implied by these detections is discussed.

  6. Experimental investigation of the factors influencing the polymer-polymer bond strength during two-component injection moulding

    DEFF Research Database (Denmark)

    Islam, Aminul; Hansen, Hans Nørgaard; Bondo, Martin

    2010-01-01

    Two-component injection moulding is a commercially important manufacturing process and a key technology for combining different material properties in a single plastic product. It is also one of most industrially adaptive process chain for manufacturing so-called moulded interconnect devices (MID...

  7. Rebrightening of XRF 030723: further evidence for a two-component jet in gamma-ray burst

    CERN Document Server

    Huang, Y F; Dai, Z G; Ma, H T; Lu, T

    2004-01-01

    Optical afterglows from two-component jets under various configurations are investigated numerically. Generally, the light curve is characterized by a rapid rebrightening when the observer is off-axis with respect to the narrow component, with the amplitude and peak time depending on detailed parameters. We further show that the optical afterglow of XRF 030723, especially its notable and rapid rebrightening, can be well explained by a typical two-component jet. This X-ray flash, together with GRB 030329, strongly hints the two-component jet model as a unified picture for X-ray flashes and gamma-ray bursts. With a narrow but ultra-relativistic inner outflow and a wide but less energetic outer ejecta, a two-component jet will be observed as a typical gamma-ray burst if our line of sight is within the angular scope of the narrow outflow. Otherwise, if the line of sight is within or slightly beyond the cone of the wide component, an X-ray flash will be detected.

  8. A Scheme of Generating and Spatially Separating Two-Component Entangled Atom Lasers

    OpenAIRE

    Liu, Xiong-Jun; Jing, Hui; Liu, Xin; Zhan, Ming-sheng; Ge, Mo-Lin

    2005-01-01

    Entanglement of remote atom lasers is obtained via quantum state transfer technique from lights to matter waves in a five-level $M$-type system. The considered atom-atom collisions can yield an effective Kerr susceptibility for this system and lead to the self- and cross- phase modulation between the two output atom lasers. This effect results in generation of entangled states of output fields. Particularly, under different conditions of space-dependent control fields, the entanglement of ato...

  9. Two-Component Signaling Regulates Osmotic Stress Adaptation via SskA and the High-Osmolarity Glycerol MAPK Pathway in the Human Pathogen Talaromyces marneffei

    Science.gov (United States)

    Cao, Cunwei; Andrianopoulos, Alex

    2016-01-01

    ABSTRACT For successful infection to occur, a pathogen must be able to evade or tolerate the host’s defense systems. This requires the pathogen to first recognize the host environment and then signal this response to elicit a complex adaptive program in order to activate its own defense strategies. In both prokaryotes and eukaryotes, two-component signaling systems are utilized to sense and respond to changes in the external environment. The hybrid histidine kinases (HHKs) at the start of the two-component signaling pathway have been well characterized in human pathogens. However, how these HHKs regulate processes downstream currently remains unclear. This study describes the role of a response regulator downstream of these HHKs, sskA, in Talaromyces marneffei, a dimorphic human pathogen. sskA is required for asexual reproduction, hyphal morphogenesis, cell wall integrity, osmotic adaptation, and the morphogenesis of yeast cells both in vitro at 37°C and during macrophage infection, but not during dimorphic switching. Comparison of the ΔsskA mutant with a strain in which the mitogen-activated protein kinase (MAPK) of the high-osmolarity glycerol pathway (SakA) has been deleted suggests that SskA acts upstream of this pathway in T. marneffei to regulate these morphogenetic processes. This was confirmed by assessing the amount of phosphorylated SakA in the ΔsskA mutant, antifungal resistance due to a lack of SakA activation, and the ability of a constitutively active sakA allele (sakAF316L) to suppress the ΔsskA mutant phenotypes. We conclude that SskA regulates morphogenesis and osmotic stress adaptation in T. marneffei via phosphorylation of the SakA MAPK of the high-osmolarity glycerol pathway. IMPORTANCE This is the first study in a dimorphic fungal pathogen to investigate the role of a response regulator downstream of two-component signaling systems and its connection to the high-osmolarity glycerol pathway. This study will inspire further research into

  10. Continuum model of the two-component Becker-Döring equations

    Directory of Open Access Journals (Sweden)

    Ali Reza Soheili

    2004-10-01

    Full Text Available The process of collision between particles is a subject of interest in many fields of physics, astronomy, polymer physics, atmospheric physics, and colloid chemistry. If two types of particles are allowed to participate in the cluster coalescence, then the time evolution of the cluster distribution has been described by an infinite system of ordinary differential equations. In this paper, we describe the model with a second-order two-dimensional partial differential equation, as a continuum model.

  11. Spatially resolved imaging of the two-component eta Crv debris disk with Herschel

    CERN Document Server

    Duchene, G; Wyatt, M; Kennedy, G; Sibthorpe, B; Lisse, C; Holland, W; Wisniewski, J; Clampin, M; Kalas, P; Pinte, C; Wilner, D; Booth, M; Horner, J; Matthews, B; Greaves, J

    2014-01-01

    We present far-infrared and sub-millimeter images of the eta Crv debris disk system obtained with Herschel and SCUBA-2, as well as Hubble Space Telescope visible and near-infrared coronagraphic images. In the 70 micron Herschel image, we clearly separate the thermal emission from the warm and cold belts in the system, find no evidence for a putative dust population located between them, and precisely determine the geometry of the outer belt. We also find marginal evidence for azimuthal asymmetries and a global offset of the outer debris ring relative to the central star. Finally, we place stringent upper limits on the scattered light surface brightness of the outer ring. Using radiative transfer modeling, we find that it is impossible to account for all observed properties of the system under the assumption that both rings contain dust populations with the same properties. While the outer belt is in reasonable agreement with the expectations of steady-state collisional cascade models, albeit with a minimum gr...

  12. VISCOELASTICITY AND IONIC CONDUCTIVITY OF TWO-COMPONENT EPOXY NETWORK CONTAINING LITHIUM PERCHLORATE

    Institute of Scientific and Technical Information of China (English)

    PENG Xinsheng; BA Hengfei; QIAO Ziwen; CHEN Donglin; WANG Fosong

    1991-01-01

    Polymeric solid electrolyte system composed of triglycidyl ether of glycerol (TGEG), diglycidyl ether of polyethylene glycol (DGEPEG)and LiClO4 salt were synthesized. In this system the electrolyte has a pecularity that not merely can the LiClO4 provide ionic carriers, but also catalyze the crosslinking reaction without adding an usual curing agent. The effect of salt content and degree of crosslinking on the viscoelasticity and ionic conductivity were studied. Both WLF and VTF equations were used to treat the experimental data in order to elucidate the mechanism of ionic conduction. It was found that the ionic conductivity of the system is carried out through the segmental motion mechanism. However, the data must be treated with care. For example, in evaluating WLF parameters, the contribution concerned with ionic carrier generation with temperature to the conductivity must be differentiated from that concerned with segmental motion. Besides, the temperature range suitable to WLF equation must also be considered. For VTF equation, it might be inapplicable if the temperature is too low and close to the glass transition temperature of the specimen. Further study is needed in order to have a quantitative information on the limitation of these equations.

  13. Spatially resolved imaging of the two-component η Crv debris disk with Herschel

    International Nuclear Information System (INIS)

    We present far-infrared and submillimeter images of the η Crv debris disk system obtained with Herschel and SCUBA-2, as well as Hubble Space Telescope visible and near-infrared coronagraphic images. In the 70 μm Herschel image, we clearly separate the thermal emission from the warm and cold belts in the system, find no evidence for a putative dust population located between them, and precisely determine the geometry of the outer belt. We also find marginal evidence for azimuthal asymmetries and a global offset of the outer debris ring relative to the central star. Finally, we place stringent upper limits on the scattered light surface brightness of the outer ring. Using radiative transfer modeling, we find that it is impossible to account for all observed properties of the system under the assumption that both rings contain dust populations with the same properties. While the outer belt is in reasonable agreement with the expectations of steady-state collisional cascade models, albeit with a minimum grain size that is four times larger than the blow-out size, the inner belt appears to contain copious amounts of small dust grains, possibly below the blow-out size. This suggests that the inner belt cannot result from a simple transport of grains from the outer belt and rather supports a more violent phenomenon as its origin. We also find that the emission from the inner belt has not declined over three decades, a much longer timescale than its dynamical timescale, which indicates that the belt is efficiently replenished.

  14. Spatially resolved imaging of the two-component η Crv debris disk with Herschel

    Energy Technology Data Exchange (ETDEWEB)

    Duchêne, G.; Arriaga, P.; Kalas, P. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Wyatt, M.; Kennedy, G. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Sibthorpe, B. [SRON Netherlands Institute for Space Research, P.O. Box 800, 9700 AV Groningen (Netherlands); Lisse, C. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Holland, W. [UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Wisniewski, J. [H.L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States); Clampin, M. [NASA Goddard Space Flight Center, Code 681, Greenbelt, MD 20771 (United States); Pinte, C. [UMI-FCA, CNRS/INSU, France (UMI 3386) (France); Wilner, D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Booth, M. [Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile); Horner, J. [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Matthews, B. [National Research Council of Canada Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Greaves, J. [SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS (United Kingdom)

    2014-04-01

    We present far-infrared and submillimeter images of the η Crv debris disk system obtained with Herschel and SCUBA-2, as well as Hubble Space Telescope visible and near-infrared coronagraphic images. In the 70 μm Herschel image, we clearly separate the thermal emission from the warm and cold belts in the system, find no evidence for a putative dust population located between them, and precisely determine the geometry of the outer belt. We also find marginal evidence for azimuthal asymmetries and a global offset of the outer debris ring relative to the central star. Finally, we place stringent upper limits on the scattered light surface brightness of the outer ring. Using radiative transfer modeling, we find that it is impossible to account for all observed properties of the system under the assumption that both rings contain dust populations with the same properties. While the outer belt is in reasonable agreement with the expectations of steady-state collisional cascade models, albeit with a minimum grain size that is four times larger than the blow-out size, the inner belt appears to contain copious amounts of small dust grains, possibly below the blow-out size. This suggests that the inner belt cannot result from a simple transport of grains from the outer belt and rather supports a more violent phenomenon as its origin. We also find that the emission from the inner belt has not declined over three decades, a much longer timescale than its dynamical timescale, which indicates that the belt is efficiently replenished.

  15. Direct MD simulation of liquid-solid phase equilibria for two-component plasmas

    OpenAIRE

    Schneider, A. S.; Hughto, J.; Horowitz, C. J.; Berry, D. K.

    2011-01-01

    We determine the liquid-solid phase diagram for carbon-oxygen and oxygen-selenium plasma mixtures using two-phase MD simulations. We identified liquid, solid, and interface regions using a bond angle metric. To study finite size effects, we perform 27648 and 55296 ion simulations. To help monitor non-equilibrium effects, we calculate diffusion constants $D_i$. For the carbon-oxygen system we find that $D_O$ for oxygen ions in the solid is much smaller than $D_C$ for carbon ions and that both ...

  16. Dark-dark solitons and modulational instability in miscible two-component Bose-Einstein condensates

    Energy Technology Data Exchange (ETDEWEB)

    Hoefer, M. A. [North Carolina State University, Department of Mathematics, Raleigh, North Carolina 27695 (United States); Chang, J. J.; Hamner, C.; Engels, P. [Washington State University, Department of Physics and Astronomy, Pullman, Washington 99164 (United States)

    2011-10-15

    We investigate the dynamics of two miscible superfluids experiencing fast counterflow in a narrow channel. The superfluids are formed by two distinguishable components of a trapped dilute-gas Bose-Einstein condensate (BEC). The onset of counterflow-induced modulational instability throughout the cloud is observed and shown to lead to the proliferation of dark-dark vector solitons. These solitons do not exist in single-component systems, exhibit intriguing beating dynamics, and can experience a transverse instability leading to vortex line structures. Experimental results and multidimensional numerical simulations are presented.

  17. Unstaggered-staggered solitons in two-component discrete nonlinear Schr\\"{o}dinger lattices

    CERN Document Server

    Malomed, Boris A; Van Gorder, Robert A

    2012-01-01

    We present stable bright solitons built of coupled unstaggered and staggered components in a symmetric system of two discrete nonlinear Schr\\"{o}dinger (DNLS) equations with the attractive self-phase-modulation (SPM) nonlinearity, coupled by the repulsive cross-phase-modulation (XPM) interaction. These mixed modes are of a "symbiotic" type, as each component in isolation may only carry ordinary unstaggered solitons. The results are obtained in an analytical form, using the variational and Thomas-Fermi approximations (VA and TFA), and the generalized Vakhitov-Kolokolov (VK) criterion for the evaluation of the stability. The analytical predictions are verified against numerical results. Almost all the symbiotic solitons are predicted by the VA quite accurately, and are stable. Close to a boundary of the existence region of the solitons (which may feature several connected branches), there are broad solitons which are not well approximated by the VA, and are unstable.

  18. Coarsening of self-organised clusters due to segregation in a two-component granular monolayer

    Science.gov (United States)

    Reis, Pedro Miguel; Mullin, Tom

    2001-11-01

    We present results of an experimental investigation of a horizontally vibrated quasi-2-dimensional granular mixture in which particles are mainly driven by frictional forces with the container. A new mode of particle segregation is found in which striped clusters of the larger particles spontaneously emerge out of an initially homogeneous mixture. The system exhibits a critical concentration ratio, reminiscent of a phase transition, below which segregation is suppressed. The striped structures coarsen with time and the average strip width obeys a t^1/4 powerlaw. These domains can also exhibit collective nonlinear behaviour. Both singly and doubly periodic states as well as chaotic phenomena have been found. Such dynamical states appear to be dependent on the granular temperature.

  19. Excitation spectrum and structure factor of a two-component Bose—Einstein condensate in different hyperfine states

    International Nuclear Information System (INIS)

    The elementary excitation spectrum of a two-component Bose—Einstein condensate in different hyperfine states is obtained by Green's function method. It is found to have two branches. In the long wave-length limit, the two branches of the excitation spectrum are reduced to one phonon excitation and one single-particle excitation. The single-particle one has an energy gap. When the energy gap exists, we study the Landau critical velocity and the depletion of the condensate. With the obtained Green's functions, we calculate the structure factor of a two-component condensate. It is found that the static structure factor comprises only the branch of the phonon excitation and the single-particle excitation makes no contribution to the structure factor. (general)

  20. Localization of a two-component Bose–Einstein condensate in a two-dimensional bichromatic optical lattice

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Kui-Tian, E-mail: kuitianxi@gmail.com; Li, Jinbin, E-mail: jinbin@nuaa.edu.cn; Shi, Da-Ning, E-mail: shi@nuaa.edu.cn

    2014-03-01

    We consider a weakly interacting two-component Bose–Einstein condensate (BEC) in a two-dimensional (2D) quasi-periodic bichromatic optical lattice (BOL). The problem is studied by means of split-step Crank–Nicolson method. The effects of weak intra- and inter-component interactions on localization of a two-component BEC are investigated. It is shown that in the quasi-2D regime, due to the enhanced disorder, there is no symmetry breaking like that in the one-dimensional (1D) case under a sine-typed potential, while configurations of density profiles are also quite different from that in the 1D case. By modulating interactions, the interplay of disorder and weak repulsive or attractive interactions is studied in detail. The cases with sine- and cosine-typed potentials acting on components 1 and 2 respectively are also discussed.

  1. Transient two-phase two-component flow in NPP with WWER premises during loss-of coolant-accident

    International Nuclear Information System (INIS)

    The work objective was the development of a model describing processes in the premises of a NPP with water cooled reactor within the first second during lost-of-coolant-accident with the main circulation pipeline rupture. Two-phase two-component flow of water-steam-air mixture has been studied. An attempt has been made to obtain a hyperbolic set of partial differential equations in a canonical form suitable for application of the method of charakteristics in any modification. The two-phase two-component critical flow theory is considered as well as the sonic velocity corresponding to the calculated sonic velocity value as a function of the true volumetric gas contant. A calculation example is presented of the pressure history in a 1000 m3 box wherein the NPP with WWER primary circulating loop coolant is flowing (the main circulation pipeline cold branch rupture)

  2. Effects of transverse trapping on the ground state of a cigar-shaped two-component Bose—Einstein condensate

    Science.gov (United States)

    Cui, Guo-Dong; Sun, Jian-Fang; Jiang, Bo-Nan; Qian, Jun; Wang, Yu-Zhu

    2013-09-01

    We derive the coupled nonpolynomial nonlinear Schrödinger equations for a two-component Bose—Einstein condensate in a quasi-one-dimension geometry and investigate the effects of a tightly transverse trapping on the ground state and the miscibility—immiscibility threshold. We find that the density profile of the matter wavepacket is remarkably dependent on the transverse width and the effective one-dimension nonlinear coupling strengths in miscible and immiscible regimes.

  3. Nonautonomous dark soliton solutions in two-component Bose—Einstein condensates with a linear time-dependent potential

    International Nuclear Information System (INIS)

    We report the analytical nonautonomous soliton solutions (NSSs) for two-component Bose—Einstein condensates with the presence of a time-dependent potential. These solutions show that the time-dependent potential can affect the velocity of NSS. The velocity shows the characteristic of both increasing and oscillation with time. A detailed analysis for the asymptotic behavior of NSSs demonstrates that the collision of two NSSs of each component is elastic

  4. Two-component wave equation for particles of spin 1/2 and nonzero rest mass. Pt. 1

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, T. (Leeds Univ. (UK). School of Mathematics)

    1984-03-21

    Spin-1/2 particles with nonzero rest mass have hitherto been described by the field equation of Dirac, i.e. by a four-component wave function. ''Why must the wave function have four components.'' was a question posed by Feynman and Gell-Mann which they answered by using the second-order equation ((inablasub(..mu..)-Asub(..mu..))/sup 2/+sigmax(B+iE))phi=m/sup 2/phi with phi a two-component spinor. The same equation - sometimes called the relativistic Pauli equation - was studied further by Brown, Tonin and Pietschmann with specific ends in view. However, a two-component wave equation which is essentially a Schroedinger equation insomuch as it retains the form i(h/2..pi..)(dphi/dt)=Hphi and is, therefore, first order in d/dt has been considered impossible, which it certainly is, if the operators used are confined to the type ..cap alpha..d, where ..cap alpha..'s are matrices with complex elements and d's are differential operators. Biedenharn and collaborators in 1971-1972 presented a two-component alternative to Dirac's equation which was of the Schroedinger type: their approach, however, is completely different from ours. We drop all the above restrictions but one, in these papers, and discuss, in part I, the qualifications of the equation (d/sub 0/+sigmasup(k)dsub(k))psi=-kappaTpsi, where dsub(..mu..)identicald/dchisup(..mu..), sigmasup(k) are the Pauli matrices, T is the linear operator which changes the sign of t, kappa=m/sub 0/c/(h/2..pi..) and psi a two-component wave function. The equation of the particle interacting with an electromagnetic field is dealt with in part II.

  5. Comparing Response Inhibition and Flexibility for Two Components of Executive Functioning in Children with Autism Spectrum Disorder and Normal Children

    OpenAIRE

    Seyed-Mousa Kafi; Seyed-omid Sotodeh; Fatemeh Pooragha

    2013-01-01

    Objective: The aim of this study was investigating and comparing two components of executive functioning in children with high function autism with normal children.Methods: this study was correlation descriptive (causal-comparative). There were two groups, one consisted of 15 participants of children with high function autism disorder (Intelligence quotient [IQ]>80) and the other consisted of 15 normal children, all age and education matched. They were compared with two neuro-cognitive tests,...

  6. Rabi-coupled two-component Bose-Einstein condensates: Classification of the ground states, defects, and energy estimates

    Science.gov (United States)

    Aftalion, Amandine; Mason, Peter

    2016-08-01

    We classify the ground states and topological defects of two-component Bose-Einstein condensates under the effect of internal coherent Rabi coupling. We present numerical phase diagrams which show the boundaries between symmetry-breaking components and various vortex patterns (triangular, square, bound state between vortices). We estimate the Rabi energy in the Thomas-Fermi limit which allows us to have an analytical description of the point energy leading to the formation of the various vortex patterns.

  7. Modulational instability of two-component Bose-Einstein condensates in an optical lattice formed inside a cavity

    Energy Technology Data Exchange (ETDEWEB)

    Huang Jinsong; Zhang Miao; Wei Lianfu [Quantum Optoelectronics Laboratory, Southwest Jiaotong University, Chengdu 610031 (China); Xie Zhengwei, E-mail: zzwxie@yahoo.com.c, E-mail: weilianfu@gmail.co [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066 (China)

    2010-03-28

    We investigate the modulational instability (MI) of two-component Bose-Einstein condensates (BECs) in an optical lattice formed inside a cavity. By adjusting the pump-cavity detuning and the pump amplitude, the optical potentials are modified, and then the hopping parameters are altered. The relevant MI scenarios due to these changes are analysed and numerically confirmed. Our results show that the driven cavity can be utilized as a possible tool to control the MI of the BECs.

  8. Identification of the Streptococcus mutans LytST two-component regulon reveals its contribution to oxidative stress tolerance

    Directory of Open Access Journals (Sweden)

    Ahn Sang-Joon

    2012-09-01

    Full Text Available Abstract Background The S. mutans LrgA/B holin-like proteins have been shown to affect biofilm formation and oxidative stress tolerance, and are regulated by oxygenation, glucose levels, and by the LytST two-component system. In this study, we sought to determine if LytST was involved in regulating lrgAB expression in response to glucose and oxygenation in S. mutans. Results Real-time PCR revealed that growth phase-dependent regulation of lrgAB expression in response to glucose metabolism is mediated by LytST under low-oxygen conditions. However, the effect of LytST on lrgAB expression was less pronounced when cells were grown with aeration. RNA expression profiles in the wild-type and lytS mutant strains were compared using microarrays in early exponential and late exponential phase cells. The expression of 40 and 136 genes in early-exponential and late exponential phase, respectively, was altered in the lytS mutant. Although expression of comYB, encoding a DNA binding-uptake protein, was substantially increased in the lytS mutant, this did not translate to an effect on competence. However, a lrgA mutant displayed a substantial decrease in transformation efficiency, suggestive of a previously-unknown link between LrgA and S. mutans competence development. Finally, increased expression of genes encoding antioxidant and DNA recombination/repair enzymes was observed in the lytS mutant, suggesting that the mutant may be subjected to increased oxidative stress during normal growth. Although the intracellular levels of reaction oxygen species (ROS appeared similar between wild-type and lytS mutant strains after overnight growth, challenge of these strains with hydrogen peroxide (H2O2 resulted in increased intracellular ROS in the lytS mutant. Conclusions Overall, these results: (1 Reinforce the importance of LytST in governing lrgAB expression in response to glucose and oxygen, (2 Define a new role for LytST in global gene regulation and resistance

  9. A comparative experimental evaluation of uncertainty estimation methods for two-component PIV

    Science.gov (United States)

    Boomsma, Aaron; Bhattacharya, Sayantan; Troolin, Dan; Pothos, Stamatios; Vlachos, Pavlos

    2016-09-01

    Uncertainty quantification in planar particle image velocimetry (PIV) measurement is critical for proper assessment of the quality and significance of reported results. New uncertainty estimation methods have been recently introduced generating interest about their applicability and utility. The present study compares and contrasts current methods, across two separate experiments and three software packages in order to provide a diversified assessment of the methods. We evaluated the performance of four uncertainty estimation methods, primary peak ratio (PPR), mutual information (MI), image matching (IM) and correlation statistics (CS). The PPR method was implemented and tested in two processing codes, using in-house open source PIV processing software (PRANA, Purdue University) and Insight4G (TSI, Inc.). The MI method was evaluated in PRANA, as was the IM method. The CS method was evaluated using DaVis (LaVision, GmbH). Utilizing two PIV systems for high and low-resolution measurements and a laser doppler velocimetry (LDV) system, data were acquired in a total of three cases: a jet flow and a cylinder in cross flow at two Reynolds numbers. LDV measurements were used to establish a point validation against which the high-resolution PIV measurements were validated. Subsequently, the high-resolution PIV measurements were used as a reference against which the low-resolution PIV data were assessed for error and uncertainty. We compared error and uncertainty distributions, spatially varying RMS error and RMS uncertainty, and standard uncertainty coverages. We observed that qualitatively, each method responded to spatially varying error (i.e. higher error regions resulted in higher uncertainty predictions in that region). However, the PPR and MI methods demonstrated reduced uncertainty dynamic range response. In contrast, the IM and CS methods showed better response, but under-predicted the uncertainty ranges. The standard coverages (68% confidence interval) ranged from

  10. Five new Fast Radio Bursts from the HTRU high latitude survey: first evidence for two-component bursts

    CERN Document Server

    Champion, D J; Kramer, M; Keith, M J; Bailes, M; Barr, E D; Bates, S D; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Flynn, C M L; Jameson, A; Johnston, S; Ng, C; Levin, L; Possenti, A; Stappers, B W; van Straten, W; Tiburzi, C; Lyne, A G

    2015-01-01

    The detection of five new fast radio bursts (FRBs) found in the High Time Resolution Universe high latitude survey is presented. The rate implied is 6$^{+4}_{-3}\\times~10^3$ (95%) FRBs sky$^{-1}$ day$^{-1}$ above a fluence of between 0.13 and 5.9 Jy ms for FRBs between 0.128 and 262 ms in duration. One of these FRBs has a clear two-component profile, each component is similar to the known population of single component FRBs and are separated by 2.4(4) ms. All the FRB components appear to be unresolved following deconvolution with a scattering tail and accounting for intra-channel smearing. The two-component FRB also has the highest dispersion measure (1629 pc cm$^{-3}$) of any FRB to-date. Many of the proposed models to explain FRBs use a single high energy event involving compact objects (such as neutron star mergers) and therefore cannot easily explain a two-component FRB. Models that are based on extreme versions of flaring, pulsing or orbital events however could produce multiple component profiles. The c...

  11. Localization of a two-component Bose–Einstein condensate in a one-dimensional random potential

    International Nuclear Information System (INIS)

    We consider a weakly interacting two-component Bose–Einstein condensate (BEC) in a one-dimensional random speckle potential. The problem is studied with solutions of Gross–Pitaevskii (GP) equations by means of numerical method in Crank–Nicolson scheme. Properties of various cases owing to the competition of disorder and repulsive interactions of a cigar-shaped two-component BEC are discussed in detail. It is shown that in the central region, phase separation of a two-component BEC is not only affected by the intra- and inter-component interactions, but also influenced by the strength of the random speckle potential. Due to the strong disorder of the potential, the criterion of phase separation which is independent of the trap strength in an ordered potential, such as a harmonic potential, is no longer available. The influence of different random numbers generated by distinct processes on localization of BEC in the random potential is also investigated, as well as the configurations of the density profiles in the tail regions

  12. Localization of a two-component Bose–Einstein condensate in a one-dimensional random potential

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Kui-Tian; Li, Jinbin, E-mail: jinbin@nuaa.edu.cn; Shi, Da-Ning, E-mail: shi@nuaa.edu.cn

    2015-02-15

    We consider a weakly interacting two-component Bose–Einstein condensate (BEC) in a one-dimensional random speckle potential. The problem is studied with solutions of Gross–Pitaevskii (GP) equations by means of numerical method in Crank–Nicolson scheme. Properties of various cases owing to the competition of disorder and repulsive interactions of a cigar-shaped two-component BEC are discussed in detail. It is shown that in the central region, phase separation of a two-component BEC is not only affected by the intra- and inter-component interactions, but also influenced by the strength of the random speckle potential. Due to the strong disorder of the potential, the criterion of phase separation which is independent of the trap strength in an ordered potential, such as a harmonic potential, is no longer available. The influence of different random numbers generated by distinct processes on localization of BEC in the random potential is also investigated, as well as the configurations of the density profiles in the tail regions.

  13. A two-component volatile atmosphere for Pluto. I. The bulk hydrodynamic escape regime

    International Nuclear Information System (INIS)

    The seasonal effects on Pluto's atmosphere of a simplified system of CH4 and N2 saturated over a solid solution are investigated, and the results are compared with previous CH4 models. It is found that bulk escape occurs for CH4 mole fractions less than 0.7 of Pluto's volatile reservoir. Greater CH4 abundance leads to diffusive separation during the escape of both species and an atmospheric mixing ratio of about Xc(0). If Xc(0) is in the range 0.02-0.10, Pluto's atmosphere remains largely intact at aphelion rather than virtually freezing out as it does for Xc(0) greater than 0.3 or less than 0.001, or form an atmosphere with only a single volatile gas. An upper limit for the CH4 mixing ratio is about 0.07 if N2 is the second gas. On the other hand, CH4 is the dominant surface constituent of the volatile deposit if Xc(0) is greater than 0.0001. 29 refs

  14. The transport co-efficients of two component hot hadronic matter

    International Nuclear Information System (INIS)

    Heavy ion collision experiments at RHIC showed large elliptic flow of emitted hadrons. This lead to the conclusion that the quark gluon plasma behaves as a nearly perfect fluid. This interpretation is based on the small but finite value of shear viscosity to entropy density ratio η/s. This gave rise to a great interest in transport coefficients of both partonic as well as hadronic matter. Hydrodynamic equations may be derived from entropy considerations using the second law of thermodynamics, a microscopic approach is necessary in order to determine the parameters, e.g., the coefficients of shear and bulk viscosity, thermal conductivity. The Boltzmann transport equation has been used extensively to estimate the transport coefficients of relativistic imperfect fluids. Pions form the most significant part of hadronic system, and quite a few estimations of the transport coefficients of pion gas are available. Nucleons also form a significant bulk of the hadronic matter produced in heavy ion collision. We aim to find the medium effect on the transport coefficients of this hadronic matter composed of mainly pions and nucleons. Here we try to find an estimation of the medium effect on the transport coefficient by employing relaxation time formalism

  15. VLT spectroscopy of XTE J2123-058 during quiescence: the masses of the two components

    Science.gov (United States)

    Casares, J.; Dubus, G.; Shahbaz, T.; Zurita, C.; Charles, P. A.

    2002-01-01

    We present Very Large Telescope (VLT) low-resolution spectroscopy of the neutron star X-ray transient XTE J2123-058 during its quiescent state. Our data reveal the presence of a K7V companion which contributes 77 per cent to the total flux at λ6300 and orbits the neutron star at K2=287+/-12kms-1. Contrary to other soft X-ray transients (SXTs), the Hα emission is almost exactly in antiphase with the velocity curve of the optical companion. Using the light-centre technique we obtain K1=140+/-27kms-1 and hence q=K1/K2=M2/M1=0.49+/-0.10. This, combined with a previous determination of the inclination angle (i=73°+/-4°) yields M1=1.55+/-0.31Msolar and M2=0.76+/-0.22Msolar. M2 agrees well with the observed spectral type. Doppler tomography of the Hα emission shows a non-symmetric accretion disc distribution mimicking that seen in SW Sex stars. Although we find a large systemic velocity of - 110+/-8kms-1 this value is consistent with the galactic rotation velocity at the position of J2123-058, and hence a halo origin. The formation scenario of J2123-058 is still unresolved.

  16. Effect of FLR and rotation on the Rayleigh-Taylor instability of two component plasma

    International Nuclear Information System (INIS)

    The problem of Rayleigh-Taylor (R-T) instability of superposed magnetized fluids is investigated in a partially ionized medium. The fluid has ionized and neutralized particles components interacting with each other by collisions. The effect of rotation in the horizontal directions also included in this R-T problem. The usual magnetohydrodynamic equations are modified for finite Larmor radius corrections which is in the form of tensor. The permeability of medium is also included in the equation. The relevant linearized perturbation equation are taken and using normal mode analysis the general relation is obtained. The dispersion relation for two superimposed fluids of different densities is derived. The dispersion relation shows that the growth rate of unstable system is reduced due to FLR corrections, rotation and collisional frequency of the neutrals. The dispersions relation gives no effect of magnetic field because horizontal magnetic field has no role in the R-T instability. The condition of instability remains unaffected by the permeability of porous medium, pressure of neutral particles in the fluids and rotation. (author)

  17. Fourth Moment Sum Rule for the Charge Correlations of a Two-Component Classical Plasma

    Science.gov (United States)

    Alastuey, Angel; Fantoni, Riccardo

    2016-05-01

    We consider an ionic fluid made with two species of mobile particles carrying either a positive or a negative charge. We derive a sum rule for the fourth moment of equilibrium charge correlations. Our method relies on the study of the system response to the potential created by a weak external charge distribution with slow spatial variations. The induced particle densities, and the resulting induced charge density, are then computed within density functional theory, where the free energy is expanded in powers of the density gradients. The comparison with the predictions of linear response theory provides a thermodynamical expression for the fourth moment of charge correlations, which involves the isothermal compressibility as well as suitably defined partial compressibilities. The familiar Stillinger-Lovett condition is also recovered as a by-product of our method, suggesting that the fourth moment sum rule should hold in any conducting phase. This is explicitly checked in the low density regime, within the Abe-Meeron diagrammatical expansions. Beyond its own interest, the fourth-moment sum rule should be useful for both analyzing and understanding recently observed behaviours near the ionic critical point.

  18. Fitting a Two- Component Scattering Model to Polarimetric SAR Data from Forests

    Science.gov (United States)

    Freeman, A.

    2007-03-01

    Two simple scattering mechanisms are f itted to polarimetric SAR observations of forests. The mechanisms are canopy scatter from a reciprocal medium with azimuthal symmetry, and a ground scatter term, which can represent double-bounce scatter from a pair of orthogonal surfaces with different d ielectric constants or Bragg scatter from a moderately rough surface, seen through a layer of vertically oriented scatterers. The model is shown to represent the behavior of polarimetric backscatter from a tropical forest and two temperate forest sites, by applying it to data from NASA/JPL's AIRSAR system. Scattering contributions from the two basic scattering mechanisms are estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. This model fit approach is justified as a simplification of more complicated scattering models, which require many inputs to solve the forward scattering problem. The model is used to develop an understanding of the ground-trunk, double-bounce scattering present in the data, which is seen to vary considerably as a function of incidence angle. Two parameters in the model fit appear to exhibit sensitivity to vegetation canopy structure, which is worth further exploration. Results from the model fit for the ground scattering term are compared with estimates from a forward model and shown to be in good agreement. The behavior of the scattering from the ground-trunk interaction is consistent with the presence of a pseudo-Brewster angle effect for the air- trunk scattering interface. If the Brewster angle is known, it is possible to directly estimate the real part of the dielectric constant of the trunks, a key variable in forward modeling of backscatter from forests. It is also shown how, with a priori knowledge of the forest height, an estimate for the attenuation coefficient of the canopy can be obtained directly from the multi-incidence angle, polarimetric

  19. Fitting a Two-Component Scattering Model to Polarimetric SAR Data from Forests

    Science.gov (United States)

    Freeman, Anthony

    2007-01-01

    Two simple scattering mechanisms are fitted to polarimetric synthetic aperture radar (SAR) observations of forests. The mechanisms are canopy scatter from a reciprocal medium with azimuthal symmetry and a ground scatter term that can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a moderately rough surface, which is seen through a layer of vertically oriented scatterers. The model is shown to represent the behavior of polarimetric backscatter from a tropical forest and two temperate forest sites by applying it to data from the National Aeronautic and Space Agency/Jet Propulsion Laboratory's Airborne SAR (AIRSAR) system. Scattering contributions from the two basic scattering mechanisms are estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. This model fit approach is justified as a simplification of more complicated scattering models, which require many inputs to solve the forward scattering problem. The model is used to develop an understanding of the ground-trunk double-bounce scattering that is present in the data, which is seen to vary considerably as a function of incidence angle. Two parameters in the model fit appear to exhibit sensitivity to vegetation canopy structure, which is worth further exploration. Results from the model fit for the ground scattering term are compared with estimates from a forward model and shown to be in good agreement. The behavior of the scattering from the ground-trunk interaction is consistent with the presence of a pseudo-Brewster angle effect for the air-trunk scattering interface. If the Brewster angle is known, it is possible to directly estimate the real part of the dielectric constant of the trunks, a key variable in forward modeling of backscatter from forests. It is also shown how, with a priori knowledge of the forest height, an estimate for the

  20. Quasi-analytical determination of noise-induced error limits in lidar retrieval of aerosol backscatter coefficient by the elastic, two-component algorithm.

    Science.gov (United States)

    Sicard, Michaël; Comerón, Adolfo; Rocadenbosch, Francisco; Rodríguez, Alejandro; Muñoz, Constantino

    2009-01-10

    The elastic, two-component algorithm is the most common inversion method for retrieving the aerosol backscatter coefficient from ground- or space-based backscatter lidar systems. A quasi-analytical formulation of the statistical error associated to the aerosol backscatter coefficient caused by the use of real, noise-corrupted lidar signals in the two-component algorithm is presented. The error expression depends on the signal-to-noise ratio along the inversion path and takes into account "instantaneous" effects, the effect of the signal-to-noise ratio at the range where the aerosol backscatter coefficient is being computed, as well as "memory" effects, namely, both the effect of the signal-to-noise ratio in the cell where the inversion is started and the cumulative effect of the noise between that cell and the actual cell where the aerosol backscatter coefficient is evaluated. An example is shown to illustrate how the "instantaneous" effect is reduced when averaging the noise-contaminated signal over a number of cells around the range where the inversion is started. PMID:19137026

  1. Effects of transverse trapping on the ground state of a cigar-shaped two-component Bose—Einstein condensate

    International Nuclear Information System (INIS)

    We derive the coupled nonpolynomial nonlinear Schrödinger equations for a two-component Bose—Einstein condensate in a quasi-one-dimension geometry and investigate the effects of a tightly transverse trapping on the ground state and the miscibility—immiscibility threshold. We find that the density profile of the matter wavepacket is remarkably dependent on the transverse width and the effective one-dimension nonlinear coupling strengths in miscible and immiscible regimes. (condensed matter: structural, mechanical, and thermal properties)

  2. A two-component wave equation for particles of spin 1/2 and nonzero rest mass: Pt. 1

    International Nuclear Information System (INIS)

    Spin-1/2 particles with nonzero rest mass have hitherto been described by the field equation of Dirac, i.e. by a four component wave function. 'Why must the wave function have four components' was a question posed by Feynman and Gell-Mann which they answered by using the second-order equation [(inablasub(μ) - Asub(μ))2 + sigma.(B + iE)]phi = m2phi with phi a two-component spinor. The same equation-sometimes called the relativistic Pauli equation-was studied further by Brown, Tonin and Pietschmann with specific ends in view. However, a two-component wave equation which is essentially a Schroedinger equation insomuch as it retains the form i(h/2π)(deltaphi/deltat) = Hphi and is, therefore, first order in delta/deltat has been considered impossible, which it certainly is, if the operators used are confined to the type αdelta, where α's are matrices with complex elements and delta's are differential operators. Biedenharn and collaborators in 1971-1972 presented a two-component alternative to Dirac's equation which was of the Schroedinger type: their approach, however, is completely different from ours. They are dropped all the above restrictions but one, in these papers, and discussed, in part I, the qualifications of the equation (delta0 + sigmasup(k)deltasub(k))psi = -xTpsi, where deltasub(μ) identical delta/deltaxsup(μ), sigmasup(k) are the Pauli matrices, T is the linear operator which changes the sign of t, x = m0c/(h/2π) and psi a two-component wave function. The equation of the particle interacting with an electromagnetic field is dealt with in part II. In part I it has been established that both components of all the solutions of the above equation satisfy the Klein-Gordon equation and that a 1-1 correspondence can be set up between its solutions and the positive-energy solutions of the Dirac equation which preserves inner products (when suitably defined for our case). Covariance under the proper Lorentz group followed by covariance under space and time

  3. Matter-Wave Solitons in Two-Component Bose-Einstein Condensates with Tunable Interactions and Time Varying Potential

    Institute of Scientific and Technical Information of China (English)

    宣恒农; 左苗

    2011-01-01

    We present three families of exact matter-wave soliton solutions for an effective one-dimension two- component Bose-Einstein condensates (BECs) with tunable interactions, harmonic potential and gain or loss term. We investigate the dynamics of bright-bright solitons, bright-dark solitons and dark-dark solitons for the time-dependent expulsive harmonic trap potential, periodically modulated harmonic trap potential, and kinklike modulated harmonic trap potential. Through the Feshbach resonance, these dynamics can be realized in experiments by suitable control of time-dependent trap parameters, atomic interactions, and interaction with thermal cloud.

  4. Two-component molecular tagging velocimetry utilizing NO fluorescence lifetime and NO2 photodissociation techniques in an underexpanded jet flowfield

    International Nuclear Information System (INIS)

    We report the application of molecular tagging velocimetry (MTV) toward two-component velocimetry as demonstrated in an underexpanded free jet flowfield. Two variants of the MTV technique are presented: 1) electronic excitation of seeded nitric oxide (NO) with gated fluorescence imaging (fluorescence lifetime) and 2) photodissociation of seeded NO2 followed by NO fluorescence imaging (NO2 photodissociation). The seeded NO fluorescence lifetime technique is advantageous in low-quenching, high-velocity flowfields, while the photodissociation technique is useful in high-quenching environments, and either high- or low-velocity flowfields due to long lifetime of the NO photoproduct. Both techniques are viable for single-shot measurements, with determined root mean squared results for streamwise and radial velocities of ∼5%. This study represents the first known application of MTV utilizing either the fluorescence lifetime or the photodissociation technique toward two-component velocity mapping in a gaseous flowfield. Methods for increasing the spatial resolution to be comparable to particle-based tracking techniques are discussed.

  5. Experimental and analytical investigation of the turbulent burning velocity of two-component fuel mixtures of hydrogen, methane and propane

    Energy Technology Data Exchange (ETDEWEB)

    Muppala, S.P.R.; Wen, J.X. [Faculty of Engineering, Kingston University, Friars Avenue, Roehampton Vale, London, SW15 3DW (United Kingdom); Nakahara, M. [Department of Engineering for Production and Environment, Ehime University 3, Bunkyo-cho, Matsuyama 790-8577 (Japan); Aluri, N.K. [Institut fuer Technische Verbrennung, Leibniz Universitaet Hannover Welfengarten 1 A, 30167 Hannover (Germany); Kido, H. [Kyushu Polytechnic College 1665-1, Shii, Kokuraminami-ku, Kitakyushu, 802-0985 790-8577 (Japan); Papalexandris, M.V. [Departement de Mecanique, Unite de Thermodynamique, Universite catholique de Louvain Place du Levant, 2; 1348 Louvain-la-Neuve (Belgium)

    2009-11-15

    In this paper, we present some experimental and analytical model results of two-component fuel mixtures of methane, propane and hydrogen. Experimentally obtained turbulent burning velocity S{sub T} for outwardly propagating spherical lean turbulent premixed flames is examined with an algebraic flame surface wrinkling reaction model using 1) mean local burning velocity, and 2) the critical chemical time scale from the leading edge model by Zel'dovich and Frank-Kamenetskii. Based on the latter approach, the time scale that characterizes the effects of preferential diffusion phenomenon in critically curved spherical flames is incorporated into the reaction model. For this, a proposed simple linear model is used for estimating the effective Lewis number of the two-component fuel (CH{sub 4}-H{sub 2} and C{sub 3}H{sub 8}-H{sub 2})/Air mixtures. In general, both approaches are effective ways in achieving qualitatively consistent S{sub T} trends for both mixtures. However, in the second approach, model predictions show large S{sub T} deviation especially at high turbulence. This may be attributed to the use of approximate values of activation temperature and for the use of the effective Lewis number of both mixtures based on the simple linear model. (author)

  6. Controlling of Fusion of Two Solitons in a Two-Component Condensate by an Anharmonic External Potential

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Qiang; WANG Deng-Long; LUO Xiao-Qing; HE Zhang-Ming; DING Jian-Wen

    2011-01-01

    By using the multiple-scale method, we analytically study dynamical properties of two-component Bose-Einstein condensates trapped in a harmonic plus quartic anharmonic potential.It is shown that the anharmonic potential has an important effect on the dark solitons of the condensates.In particular, when the strength of the anharmonic external potential increases, the fusion of the two solitons becomes faster.This implies that the fusion of the two solitons can be controlled by an anharmonic potential.%@@ By using the multiple-scale method,we analytically study dynamical properties of two-component Bose-Einstein condensates trapped in a harmonic plus quartic anharmonic potential.It is shown that the anharmonic potential has an important effect on the dark solitons of the condensates.In particular,when the strength of the anharmonic external potential increases,the fusion of the two solitons becomes faster.This implies that the fusion of the two solitons can be controlled by an anharmonic potential.

  7. Stable and unstable vector dark solitons of coupled nonlinear Schroedinger equations: Application to two-component Bose-Einstein condensates

    International Nuclear Information System (INIS)

    The dynamics of vector dark solitons in two-component Bose-Einstein condensates is studied within the framework of coupled one-dimensional nonlinear Schroedinger (NLS) equations. We consider the small-amplitude limit in which the coupled NLS equations are reduced to coupled Korteweg-de Vries (KdV) equations. For a specific choice of the parameters the obtained coupled KdV equations are exactly integrable. We find that there exist two branches of (slow and fast) dark solitons corresponding to the two branches of the sound waves. Slow solitons, corresponding to the lower branch of the acoustic wave, appear to be unstable and transform during the evolution into stable fast solitons (corresponding to the upper branch of the dispersion law). Vector dark solitons of arbitrary depths are studied numerically. It is shown that effectively different parabolic traps, to which the two components are subjected, cause an instability of the solitons, leading to a splitting of their components and subsequent decay. A simple phenomenological theory, describing the oscillations of vector dark solitons in a magnetic trap, is proposed

  8. Discovery and Characterization of Bicereucin, an Unusual d-Amino Acid-Containing Mixed Two-Component Lantibiotic.

    Science.gov (United States)

    Huo, Liujie; van der Donk, Wilfred A

    2016-04-27

    Lantibiotics are a group of ribosomally synthesized and post-translationally modified peptides (RiPPs) exhibiting antimicrobial activity. They are characterized by the presence of the thioether-containing bisamino acids lanthionine and methyllanthionine. Here, we report a two-component lantibiotic from Bacillus cereus SJ1 with unusual structural features that we named bicereucin. Unlike all previous two-component lantibiotics, only one of the two peptides of bicereucin contains a lanthionine. The second peptide lacks any cysteines but contains several d-amino acids. These are installed by the dehydrogenase BsjJB, the activity of which was successfully reconstituted in vitro. The proteolytic removal of the leader peptide was also performed in vitro. Bicereucin displayed synergistic antimicrobial activities against Gram-positive strains including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci as well as hemolytic activity. To illustrate the utility of the enzymes, an analog of the d-amino acid containing opioid dermorphin was successfully produced in E. coli by employing the dehydratase BsjM and the dehydrogenase NpnJA. PMID:27074593

  9. A two wavelength holographic technique for simultaneous measurement of temperature and concentration during the solidification of two component systems

    Science.gov (United States)

    Ecker, A.

    1987-01-01

    Simultaneous measurement of the temperature and concentration distribution within a fluid can be made using a 'two wavelength holographic' setup. The technique is successfully applied to the study of temperature, concentration, and flow fields in the melt of a transparent 'model alloy' during solidification.

  10. Interfacial dynamic and dilational rheology of polyelectrolyte/surfactant two-component nanoparticle systems at air–water interface

    Energy Technology Data Exchange (ETDEWEB)

    Tong, L.J.; Bao, M.T.; Li, Y.M., E-mail: liym@ouc.edu.cn; Gong, H.Y.

    2014-10-15

    Graphical abstract: - Highlights: • DTAB/PSS mixture can self-assemble nanoparticles in bulk solution. • The nanoparticles can adsorb at the interface forming a nanoparticle monolayer. • The nanoparticles spread at the interface undergo a disassembly process with time. • The nanoparticle monolayer presents peculiar dilational viscoelastic behavior. - Abstract: The interfacial characteristics of nanoparticles and consequent inter-particle interactions at the interface are poorly understood. In this work, the interfacial dynamic and corresponding dilational surface rheology of self-assembled polyelectrolyte/surfactant nanoparticles at the air–water interface are characterized. The nanoparticles are prepared from dodecyltrimethylammonium (DTAB) and poly (sodium 4-styrene-sulfonate) (PSS) by mixing them in aqueous solution. The interfacial dynamic characteristics have been carried out by comparing the surface pressure with the dilational rheological response of these nanoparticles at interface. The results indicate that this type of nanoparticles can adsorb at the interface forming a nanoparticle monolayer, which leads to the surface tension decreased markedly. The dependence of surface pressure on time shows the instability and disassembly process of nanoparticles at the interface. On the basis of these observations, it is proposed that the nanoparticles undergo a dynamic process that interface induced nanoparticles disassembly into DTAB/PSS complexes. The presence of PSS in the subphase can promote the process of nanoparticles disassembly. A transition point in dilational elasticity and viscosity response of the nanoparticles versus oscillation frequency further validate the micro dynamic process of nanoparticles and the formation of polyelectrolyte/surfactant complex monolayer at the interface.

  11. Interfacial dynamic and dilational rheology of polyelectrolyte/surfactant two-component nanoparticle systems at air–water interface

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • DTAB/PSS mixture can self-assemble nanoparticles in bulk solution. • The nanoparticles can adsorb at the interface forming a nanoparticle monolayer. • The nanoparticles spread at the interface undergo a disassembly process with time. • The nanoparticle monolayer presents peculiar dilational viscoelastic behavior. - Abstract: The interfacial characteristics of nanoparticles and consequent inter-particle interactions at the interface are poorly understood. In this work, the interfacial dynamic and corresponding dilational surface rheology of self-assembled polyelectrolyte/surfactant nanoparticles at the air–water interface are characterized. The nanoparticles are prepared from dodecyltrimethylammonium (DTAB) and poly (sodium 4-styrene-sulfonate) (PSS) by mixing them in aqueous solution. The interfacial dynamic characteristics have been carried out by comparing the surface pressure with the dilational rheological response of these nanoparticles at interface. The results indicate that this type of nanoparticles can adsorb at the interface forming a nanoparticle monolayer, which leads to the surface tension decreased markedly. The dependence of surface pressure on time shows the instability and disassembly process of nanoparticles at the interface. On the basis of these observations, it is proposed that the nanoparticles undergo a dynamic process that interface induced nanoparticles disassembly into DTAB/PSS complexes. The presence of PSS in the subphase can promote the process of nanoparticles disassembly. A transition point in dilational elasticity and viscosity response of the nanoparticles versus oscillation frequency further validate the micro dynamic process of nanoparticles and the formation of polyelectrolyte/surfactant complex monolayer at the interface

  12. The CssRS two-component regulatory system controls a general secretion stress response in Bacillus subtilis

    NARCIS (Netherlands)

    Westers, Helga; Westers, L; Darmon, E.; van Dijl, Jan Maarten; Quax, Wim; Zanen, Geeske

    2006-01-01

    Bacillus species are valuable producers of industrial enzymes and biopharmaceuticals, because they can secrete large quantities of high-quality proteins directly into the growth medium. This requires the concerted action of quality control factors, such as folding catalysts and 'cleaning proteases'.

  13. A subset of cytokinin two-component signaling system plays a role in cold temperature stress response in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    Jeon, J.; Kim, N. Y.; Kim, S.; Kang, N. Y.; Novák, Ondřej; Ku, S. J.; Cho, D. J.; Lee, D. J.; Lee, E. J.; Strnad, Miroslav; Kim, J.

    2010-01-01

    Roč. 285, č. 30 (2010), s. 23369-23384. ISSN 0021-9258 R&D Projects: GA ČR GA301/08/1649 Institutional research plan: CEZ:AV0Z50380511 Keywords : Histidine kinase * Gene-expression * Negative regulator Subject RIV: EF - Botanics Impact factor: 5.328, year: 2010

  14. Identification of Rhizobium-specific intergenic mosaic elements within an essential two-component regulatory system of Rhizobium species.

    OpenAIRE

    Osterås, M; Stanley, J; Finan, T. M.

    1995-01-01

    Analysis of the DNA regions upstream of the phosphoenolpyruvate carboxykinase gene (pckA) in Rhizobium meliloti and Rhizobium sp. strain NGR234 identified an open reading frame which was highly homologous to the Agrobacterium tumefaciens chromosomal virulence gene product ChvI. A second gene product, 500 bp downstream of the chvI-like gene in R. meliloti, was homologous to the A. tumefaciens ChvG protein. The homology between the R. meliloti and A. tumefaciens genes was confirmed, because the...

  15. Decomposition of hydrogen peroxide on a two-component catalyst of the type CuO-ZnO

    International Nuclear Information System (INIS)

    The decomposition was studied of hydrogen peroxide on a two-component CuO-ZnO catalyst over the whole concentration range of 0 - 100% of one component. It was found that a mutual charge interaction of both components of the catalyst takes place which is manifested by the non-monotonous character of the dependence on composition of the specific surface areas and specific catalytic activity of the samples. A model of elementary reactions was proposed to elucidate this dependence, based on the previously published principle of bivalent catalytic centers. Irradiation of samples by γ rays leads to small both negative and positive changes in catalytic activity (in dependence on composition), whereas irradiation by neutrons results in a slight decrease in the catalytic activity of the samples. These observed changes can be qualitatively interpreted in terms of the electron theory of catalysis. (author)

  16. Temperature-controlled structure and kinetics of ripple phases in one- and two-component supported lipid bilayers

    DEFF Research Database (Denmark)

    Kaasgaard, Thomas; Leidy, Chad; Crowe, J.H.; Mouritsen, Ole G.; Jørgensen, Kent

    2003-01-01

    ripples was seen. From height profiles of the AFM images, estimates of the amplitudes of the different ripple phases are reported. To elucidate the processes of ripple formation and disappearance, a ripple-phase DPPC lipid bilayer was taken through the pretransition in the cooling and the heating......Temperature-controlled atomic force microscopy (AFM) has been used to visualize and study the structure and kinetics of ripple phases in one-component dipalmitoylphosphaticlylcholine (DPPC) and two-component dimyristoylphosphatidylcholine-distearoylphosphatidylcholine (DMPC-DSPC) lipid bilayers....... The lipid bilayers are mica-supported double bilayers in which ripple-phase formation occurs in the top bilayer. In one-component DPPC lipid bilayers, the stable and metastable ripple phases were observed. In addition, a third ripple structure with approximately twice the wavelength of the metastable...

  17. Two component dark matter: a possible explanation of 130 GeV γ-ray line from the galactic centre

    International Nuclear Information System (INIS)

    Recently there has been a hint of a gamma-ray line at 130 GeV originated from the galactic centre after the analysis of the Fermi-LAT satellite data. Being monochromatic in nature, it rules out the possibility of having its astrophysical origin and there has been a speculation that this line could be originated from dark matter annihilation. In this work, we propose a two component dark matter scenario where an extension of the Standard Model by an inert Higgs doublet and a gauge singlet scalar concocted with Z2 × Z'2 symmetry, is considered. We find that our scenario can not only explain the 130 GeV gamma-ray line through dark matter annihilation but also produce the correct dark matter relic density. We have used the Standard Model Higgs mass around 125 GeV as intimated by the LHC data

  18. Use of two-component Weibull mixtures in the analysis of wind speed in the Eastern Mediterranean

    Energy Technology Data Exchange (ETDEWEB)

    Akdag, S.A. [Istanbul Technical University, Energy Institute, Ayazaga Campus, Maslak, Istanbul (Turkey); Bagiorgas, H.S.; Mihalakakou, G. [Department of Environmental and Natural Resources Management, University of Ioannina, 2 G. Sepheri Str., 30100 Agrinio (Greece)

    2010-08-15

    The statistical characteristics of wind speed data recorded at nine buoys, located in Ionian and Aegean Sea (Eastern Mediterranean) are analyzed in this paper, in order to present a more accurate method for estimation of wind speed characteristics, according to the suitability of the probability distribution functions (pdf). This article has focussed on wind regimes that present nearly zero percentages of null wind speeds. The selected distributions for examination are the typical two-parameter Weibull wind speed distribution (W-pdf) and the two-component mixture Weibull distribution (WW-pdf), involving five parameters (two shape parameters, two scale parameters, and one proportionality parameter). Suitable software, based on the maximum likelihood method, is used in order to estimate the aforementioned two-parameters of the typical W-pdf and the five parameters of the mixed WW-pdf. The suitability of the aforementioned distributions is judged from the coefficient of determination (R{sup 2}) and the fit standard error (RMSE) tests, which had been carried out between each one of the theoretical distributions and the corresponding experimental cumulative frequencies of the nine selected sites. From these tests it is clear that, in most cases (six experimental stations - having either unimodal or bimodal frequency distributions), mixed-Weibull distribution provides the highest degree of fit. In the other three cases, the mixing weight p of the two-component mixed Weibull density function equals to zero (p = 0), so the mixed-Weibull distribution is been transformed to the typical Simple-Weibull distribution. Hence, the general conclusion is that the aforementioned mixture of two Weibull distributions is more suitable for the description of such wind conditions and could offer less relative errors in determining the annual mean wind power density. (author)

  19. Characterization of GX 339-4 outburst of 2010-11: Analysis by XSPEC using Two Component Advective Flow model

    CERN Document Server

    Debnath, Dipak; Chakrabarti, Sandip K

    2013-01-01

    We study the spectral properties of the Galactic transient black hole candidate (BHC) GX 339-4 during its 2010-11 outburst with Two Component (Keplerian and sub-Keplerian) Advective Flow (TCAF) model after its inclusion in XSPEC as a local model. We also compare our TCAF model fitted results with combined disk black body (DBB) and power-law (PL) model fitted spectral results and find similar types of smooth variation in thermal (Keplerian or disk black body) as well as non-thermal (power-law or sub-Keplerian) fluxes. For spectral fit, we use 2.5-25 keV spectral data of PCA instrument onboard RXTE satellite. From the TCAF model fit, accretion flow parameters, such as the Keplerian (disk) rate, sub-Keplerian (halo) rate, location of the shock and strength of the shock are extracted. Our study provides a comprehensive understanding of the mass accretion processes and properties of the accretion disk around the BHC during the outburst phases. Based on the comparison of the halo to disk accretion rate ratio (ARR) ...

  20. Treatment of scalar-relativistic effects on nuclear magnetic shieldings using a spin-free exact-two-component approach

    Science.gov (United States)

    Cheng, Lan; Gauss, Jürgen; Stanton, John F.

    2013-08-01

    A cost-effective treatment of scalar-relativistic effects on nuclear magnetic shieldings based on the spin-free exact-two-component theory in its one-electron variant (SFX2C-1e) is presented. The SFX2C-1e scheme gains its computational efficiency, in comparison to the four-component approach, from a focus on spin-free contributions and from the elimination of the small component. For the calculation of nuclear magnetic shieldings, the separation of spin-free and spin-dependent terms in the parent four-component theory is carried out here for the matrix representation of the Dirac equation in terms of a restricted-magnetically balanced gauge-including atomic orbital basis. The resulting spin-free four-component matrix elements required to calculate nuclear magnetic shieldings are then used to construct the corresponding SFX2C-1e Hamiltonian and its perturbed counterpart in the context of SFX2C-1e analytic derivative theory. To demonstrate the applicability of the approach, we report coupled-cluster calculations for prototypical problems such as the 17O shieldings of transition-metal oxo complexes (MO_4^{2-}, M = Cr, Mo, and W) and the 129Xe shieldings of xenon fluorides (XeF2, XeF4, and XeF6).

  1. HST-Scale 3D simulations of MHD disc winds : A rotating two-component jet structure

    CERN Document Server

    Staff, Jan; Ouyed, Rachid; Thompson, Adam; Pudritz, Ralph

    2014-01-01

    We present the results of large scale, three-dimensional magneto-hydrodynamics simulations of disc-winds for different initial magnetic field configurations. The jets are followed from the source to 90 AU scale, which covers several pixels of HST images of nearby protostellar jets. Our simulations show that jets are heated along their length by many shocks. We compute the emission lines that are produced, and find excellent agreement with observations. The jet width is found to be between 20 and 30 AU while the maximum velocities perpendicular to the jet is found to be up to above 100 km/s. The initially less open magnetic field configuration simulations results in a wider, two-component jet; a cylindrically shaped outer jet surrounding a narrow and much faster, inner jet. These simulations preserve the underlying Keplerian rotation profile of the inner jet to large distances from the source. However, for the initially most open magnetic field configuration the kink mode creates a narrow corkscrew-like jet wi...

  2. A TWO-COMPONENT JET MODEL FOR THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451

    International Nuclear Information System (INIS)

    We analyze both the early- and late-time radio and X-ray data of the tidal disruption event (TDE) Swift J1644+57. The data at early times (≲ 5 days) necessitate separation of the radio and X-ray emission regions, either spatially or in velocity space. This leads us to suggest a two-component jet model, in which the inner jet is initially relativistic with Lorentz factor Γ ≈ 15, while the outer jet is trans-relativistic, with Γ ≲ 1.2. This model enables a self-consistent interpretation of the late-time radio data, both in terms of peak frequency and flux. We solve the dynamics, radiative cooling, and expected radiation from both jet components. We show that while during the first month synchrotron emission from the outer jet dominates the radio emission, at later times, radiation from ambient gas collected by the inner jet dominates. This provides a natural explanation to the observed re-brightening, without the need for late-time inner engine activity. After 100 days, the radio emission peak is in the optically thick regime, leading to a decay of both the flux and peak frequency at later times. Our model's predictions for the evolution of radio emission in jetted TDEs can be tested by future observations

  3. Influence of local-field corrections on Thomson scattering in collision-dominated two-component plasmas

    International Nuclear Information System (INIS)

    The dynamic structure factor, which determines the Thomson scattering spectrum, is calculated via an extended Mermin approach. It incorporates the dynamical collision frequency as well as the local-field correction factor. This allows to study systematically the impact of electron-ion collisions as well as electron-electron correlations due to degeneracy and short-range interaction on the characteristics of the Thomson scattering signal. As such, the plasmon dispersion and damping width is calculated for a two-component plasma, where the electron subsystem is completely degenerate. Strong deviations of the plasmon resonance position due to the electron-electron correlations are observed at increasing Brueckner parameters rs. These results are of paramount importance for the interpretation of collective Thomson scattering spectra, as the determination of the free electron density from the plasmon resonance position requires a precise theory of the plasmon dispersion. Implications due to different approximations for the electron-electron correlation, i.e., different forms of the one-component local-field correction, are discussed.

  4. Influence of local-field corrections on Thomson scattering in collision-dominated two-component plasmas

    Science.gov (United States)

    Fortmann, Carsten; Wierling, August; Röpke, Gerd

    2010-02-01

    The dynamic structure factor, which determines the Thomson scattering spectrum, is calculated via an extended Mermin approach. It incorporates the dynamical collision frequency as well as the local-field correction factor. This allows to study systematically the impact of electron-ion collisions as well as electron-electron correlations due to degeneracy and short-range interaction on the characteristics of the Thomson scattering signal. As such, the plasmon dispersion and damping width is calculated for a two-component plasma, where the electron subsystem is completely degenerate. Strong deviations of the plasmon resonance position due to the electron-electron correlations are observed at increasing Brueckner parameters rs . These results are of paramount importance for the interpretation of collective Thomson scattering spectra, as the determination of the free electron density from the plasmon resonance position requires a precise theory of the plasmon dispersion. Implications due to different approximations for the electron-electron correlation, i.e., different forms of the one-component local-field correction, are discussed.

  5. Probing red blood cell mechanics, rheology and dynamics with a two-component multi-scale model

    Science.gov (United States)

    Li, Xuejin; Peng, Zhangli; Lei, Huan; Dao, Ming; Karniadakis, George Em

    2014-01-01

    This study is partially motivated by the validation of a new two-component multi-scale cell model we developed recently that treats the lipid bilayer and the cytoskeleton as two distinct components. Here, the whole cell model is validated and compared against several available experiments that examine red blood cell (RBC) mechanics, rheology and dynamics. First, we investigated RBC deformability in a microfluidic channel with a very small cross-sectional area and quantified the mechanical properties of the RBC membrane. Second, we simulated twisting torque cytometry and compared predicted rheological properties of the RBC membrane with experimental measurements. Finally, we modelled the tank-treading (TT) motion of a RBC in a shear flow and explored the effect of channel width variation on the TT frequency. We also investigated the effects of bilayer–cytoskeletal interactions on these experiments and our simulations clearly indicated that they play key roles in the determination of cell membrane mechanical, rheological and dynamical properties. These simulations serve as validation tests and moreover reveal the capabilities and limitations of the new whole cell model. PMID:24982252

  6. Phosphorescence lifetimes of organic light-emitting diodes from two-component time-dependent density functional theory

    International Nuclear Information System (INIS)

    “Spin-forbidden” transitions are calculated for an eight-membered set of iridium-containing candidate molecules for organic light-emitting diodes (OLEDs) using two-component time-dependent density functional theory. Phosphorescence lifetimes (obtained from averaging over relevant excitations) are compared to experimental data. Assessment of parameters like non-distorted and distorted geometric structures, density functionals, relativistic Hamiltonians, and basis sets was done by a thorough study for Ir(ppy)3 focussing not only on averaged phosphorescence lifetimes, but also on the agreement of the triplet substate structure with experimental data. The most favorable methods were applied to an eight-membered test set of OLED candidate molecules; Boltzmann-averaged phosphorescence lifetimes were investigated concerning the convergence with the number of excited states and the changes when including solvent effects. Finally, a simple model for sorting out molecules with long averaged phosphorescence lifetimes is developed by visual inspection of computationally easily achievable one-component frontier orbitals

  7. A Cyclic di-GMP-binding Adaptor Protein Interacts with Histidine Kinase to Regulate Two-component Signaling.

    Science.gov (United States)

    Xu, Linghui; Venkataramani, Prabhadevi; Ding, Yichen; Liu, Yang; Deng, Yinyue; Yong, Grace Lisi; Xin, Lingyi; Ye, Ruijuan; Zhang, Lianhui; Yang, Liang; Liang, Zhao-Xun

    2016-07-29

    The bacterial messenger cyclic di-GMP (c-di-GMP) binds to a diverse range of effectors to exert its biological effect. Despite the fact that free-standing PilZ proteins are by far the most prevalent c-di-GMP effectors known to date, their physiological function and mechanism of action remain largely unknown. Here we report that the free-standing PilZ protein PA2799 from the opportunistic pathogen Pseudomonas aeruginosa interacts directly with the hybrid histidine kinase SagS. We show that PA2799 (named as HapZ: histidine kinase associated PilZ) binds directly to the phosphoreceiver (REC) domain of SagS, and that the SagS-HapZ interaction is further enhanced at elevated c-di-GMP concentration. We demonstrate that binding of HapZ to SagS inhibits the phosphotransfer between SagS and the downstream protein HptB in a c-di-GMP-dependent manner. In accordance with the role of SagS as a motile-sessile switch and biofilm growth factor, we show that HapZ impacts surface attachment and biofilm formation most likely by regulating the expression of a large number of genes. The observations suggest a previously unknown mechanism whereby c-di-GMP mediates two-component signaling through a PilZ adaptor protein. PMID:27231351

  8. Diagnostics for the structure of AGNs’broad line regions with reverberation mapping data:confirmation of the two-component broad line region model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We re-examine the ten Reverberation Mapping(RM) sources with public data based on the two-component model of the Broad Line Region(BLR).In fitting their broad Hβ Mlines,six of them only need one Gaussian component,one of them has a double-peak profile,one has an irregular profile,and only two of them need two components,i.e.,a Very Broad Gaussian Component(VBGC) and an Inter-Mediate Gaussian Component(IMGC).The Gaussian components are assumed to come from two distinct regions in the two-component model;they are the Very Broad Line Region(VBLR) and the Inter-Mediate Line region(IMLR).The two sources with a two-component profile are Mrk 509 and NGC 4051.The time lags of the two components of both sources satisfy tIMLR/tVBLR=V 2VBLR/V 2IMLR,where tIMLR and tVBLR are the lags of the two components while VIMLR and VVBLR represent the mean gas velocities of the two regions,supporting the two-component model of the BLR of Active Galactic Nuclei(AGNs).The fact that most of these ten sources only have the VBGC confirms the assumption that RM mainly measures the radius of the VBLR;consequently,the radius obtained from the R-L relationship mainly represents the radius of VBLR.Moreover,NGC 4051,with a lag of about 5 days in the one component model,is an outlier on the R-L relationship as shown in Kaspi et al.(2005);however this problem disappears in our two-component model with lags of about 2 and 6 days for the VBGC and IMGC,respectively.

  9. Ground-state and rotational properties of a two-component Bose–Einstein condensate in a harmonic plus quartic trap

    International Nuclear Information System (INIS)

    We consider a two-component Bose–Einstein condensate under extreme elongation in a harmonic plus quartic trap. The ground-state and rotational properties of such a system are numerically studied as a function of intra- and inter-component contact interactions, and of the rotational frequency. For the nonrotational case, we obtain the exact phase diagram showing the ground-state density distributions as contact-interactions varied. For both slowly and ultrarapidly rotational cases, we demonstrate that the vortex configurations depend strongly on the relative strength of the contact interactions, as well as on the rotational frequency. The controllable system may be used to investigate the interplay of interaction and rotation, and to explore more exotic quantum phases. - Highlights: • Quartic trap extends the parameter space to a fast rotating region. • Different ground state density distributions and novel vortex structures are obtained within the full parameter space. • Effects of the contact interactions and rotation are discussed in detail

  10. Ground-state and rotational properties of a two-component Bose–Einstein condensate in a harmonic plus quartic trap

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guang-Ping [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Zhi-Yuan [The School of Physics and Mech-tronic Engineering, Sichuan University of Art and Science, DaZhou 635000 (China); Dong, Biao [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Lin-Xue [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Zhang, Xiao-Fei, E-mail: xfzhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China); Zhang, Shou-Gang, E-mail: szhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China)

    2015-10-02

    We consider a two-component Bose–Einstein condensate under extreme elongation in a harmonic plus quartic trap. The ground-state and rotational properties of such a system are numerically studied as a function of intra- and inter-component contact interactions, and of the rotational frequency. For the nonrotational case, we obtain the exact phase diagram showing the ground-state density distributions as contact-interactions varied. For both slowly and ultrarapidly rotational cases, we demonstrate that the vortex configurations depend strongly on the relative strength of the contact interactions, as well as on the rotational frequency. The controllable system may be used to investigate the interplay of interaction and rotation, and to explore more exotic quantum phases. - Highlights: • Quartic trap extends the parameter space to a fast rotating region. • Different ground state density distributions and novel vortex structures are obtained within the full parameter space. • Effects of the contact interactions and rotation are discussed in detail.

  11. Remote sensing of particle dynamics: a two-component unmixing model in a western UK shelf sea.

    Science.gov (United States)

    Mitchell, Catherine; Cunningham, Alex

    2014-05-01

    The relationship between the backscattering and absorption coefficients, in particular the backscattering to absorption ratio, is mediated by the type of particles present in the water column. By considering the optical signals to be driven by phytoplankton and suspended minerals, with a relatively constant influence from CDOM, radiative transfer modelling is used to propose a method for retrieving the optical contribution of phytoplankton and suspended minerals to the total absorption coefficient with mean percentage errors of below 5% for both components. These contributions can be converted to constituent concentrations if the appropriate specific inherent optical properties are known or can be determined from the maximum and minimum backscattering to absorption ratios of the data. Remotely sensed absorption and backscattering coefficients from eight years of MODIS data for the Irish Sea reveal maximum backscattering to absorption coefficient ratios over the winter (with an average for the region of 0.27), which then decrease to a minimum over the summer months (with an average of 0.06) before increasing again through to winter, indicating a change in the particles present in the water column. Application of the two-component unmixing model to this data showed seasonal cycles of both phytoplankton and suspended mineral concentrations which vary in both amplitude and periodicity depending on their location. For example, in the Bristol Channel the amplitude of the suspended mineral concentration throughout one cycle is approximately 75% greater than a yearly cycle in the eastern Irish Sea. These seasonal cycles give an insight into the complex dynamics of particles in the water column, indicating the suspension of sediment throughout the winter months and the loss of sediments from the surface layer over the summer during stratification. The relationship between the timing of the phytoplankton spring bloom and changes in the availability of light in the water

  12. Explaining low energy γ-ray excess from the galactic centre using a two-component dark matter model

    Science.gov (United States)

    Biswas, Anirban

    2016-06-01

    Over the past few years, there has been a hint of the γ-ray excess observed by the Fermi-LAT satellite-borne telescope from the regions surrounding the galactic centre (GC) at an energy range of ˜1-3 GeV. The nature of this excess γ-ray spectrum is found to be consistent with the γ-ray emission expected from dark matter (DM) annihilation at the GC while disfavouring other known astrophysical sources as the possible origin of this phenomena. It is also reported that the spectrum and morphology of this excess γ-rays can well be explained by the DM particles having mass in the range 30{--}40 {{GeV}} annihilating significantly into b\\bar{b} final state with an annihilation cross section σ v˜ (1.4-2.0)× {10}-26 cm{}3 {{{s}}}-1 at the GC. In this work, we propose a two-component DM model where two different types of DM particles, namely a complex scalar and a Dirac fermion are considered. The stability of both the dark sector particles are maintained by virtue of an additional local {{U}}{(1)}X gauge symmetry. We find that our proposed scenario can provide a viable explanation for this anomalous excess γ-rays besides satisfying all the existing relevant theoretical as well as experimental and observational bounds from LHC, PLANCK and LUX collaborations. The allowed range of ‘effective annihilation cross section’ of lighter DM particle for the b\\bar{b} annihilation channel thus obtained is finally compared with the limits reported by the Fermi-LAT and DES collaborations using data from various dwarf spheroidal galaxies.

  13. Evolution of multidrug resistance during Staphylococcus aureus infection involves mutation of the essential two component regulator WalKR.

    Directory of Open Access Journals (Sweden)

    Benjamin P Howden

    2011-11-01

    Full Text Available Antimicrobial resistance in Staphylococcus aureus is a major public health threat, compounded by emergence of strains with resistance to vancomycin and daptomycin, both last line antimicrobials. Here we have performed high throughput DNA sequencing and comparative genomics for five clinical pairs of vancomycin-susceptible (VSSA and vancomycin-intermediate ST239 S. aureus (VISA; each pair isolated before and after vancomycin treatment failure. These comparisons revealed a frequent pattern of mutation among the VISA strains within the essential walKR two-component regulatory locus involved in control of cell wall metabolism. We then conducted bi-directional allelic exchange experiments in our clinical VSSA and VISA strains and showed that single nucleotide substitutions within either walK or walR lead to co-resistance to vancomycin and daptomycin, and caused the typical cell wall thickening observed in resistant clinical isolates. Ion Torrent genome sequencing confirmed no additional regulatory mutations had been introduced into either the walR or walK VISA mutants during the allelic exchange process. However, two potential compensatory mutations were detected within putative transport genes for the walK mutant. The minimal genetic changes in either walK or walR also attenuated virulence, reduced biofilm formation, and led to consistent transcriptional changes that suggest an important role for this regulator in control of central metabolism. This study highlights the dramatic impacts of single mutations that arise during persistent S. aureus infections and demonstrates the role played by walKR to increase drug resistance, control metabolism and alter the virulence potential of this pathogen.

  14. The weathervane model, a functional and structural organization of the two-component alkanesulfonate oxidoreductase SsuD from Xanthomonas citri

    Energy Technology Data Exchange (ETDEWEB)

    Pegos, V.R. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Oliveira, P.S.L.; Balan, A. [Laboratorio Nacional de Biociencias - LNBIO, Campinas, SP (Brazil)

    2012-07-01

    Full text: In Xanthomonas citri, the phytopathogen responsible for the canker citrus disease, we identified in the ssuABCDE operon, genes encoding the alkanesulfonate ABC transporter as well as the two enzymes responsible for oxido reduction of the respective substrates. SsuD and SsuE proteins represent a two-component system that can be assigned to the group of FMNH{sub 2} -dependent monooxygenases. How- ever, despite of the biochemical information about SsuD and SsuE orthologs from Escherichia coli, there is no structural information of how the two proteins work together. In this work, we used ultracentrifugation, SAXS data and molecular modeling to construct a structural/functional model, which consists of eight molecules organized in a weathervane shape. Through this model, SsuD ligand-binding site for NADPH{sub 2} and FMN substrates is clearly exposed, in a way that might allow the protein-protein interactions with SsuE. Moreover, based on molecular dynamics simulations of SsuD in apo state, docked with NADPH{sub 2}, FMN or both substrates, we characterized the residues of the pocket, the mechanism of substrate interaction and transfer of electrons from NADPH{sub 2} to FMN. This is the first report that links functional and biochemical data with structural analyses. (author)

  15. The weathervane model, a functional and structural organization of the two-component alkanesulfonate oxidoreductase SsuD from Xanthomonas citri

    International Nuclear Information System (INIS)

    Full text: In Xanthomonas citri, the phytopathogen responsible for the canker citrus disease, we identified in the ssuABCDE operon, genes encoding the alkanesulfonate ABC transporter as well as the two enzymes responsible for oxido reduction of the respective substrates. SsuD and SsuE proteins represent a two-component system that can be assigned to the group of FMNH2 -dependent monooxygenases. How- ever, despite of the biochemical information about SsuD and SsuE orthologs from Escherichia coli, there is no structural information of how the two proteins work together. In this work, we used ultracentrifugation, SAXS data and molecular modeling to construct a structural/functional model, which consists of eight molecules organized in a weathervane shape. Through this model, SsuD ligand-binding site for NADPH2 and FMN substrates is clearly exposed, in a way that might allow the protein-protein interactions with SsuE. Moreover, based on molecular dynamics simulations of SsuD in apo state, docked with NADPH2, FMN or both substrates, we characterized the residues of the pocket, the mechanism of substrate interaction and transfer of electrons from NADPH2 to FMN. This is the first report that links functional and biochemical data with structural analyses. (author)

  16. Two-component co-injection and transfer molding and gas-assisted injection molding of polymers: Simulation and experiment

    Science.gov (United States)

    Li, Chengtao

    Two-component molding is a novel process for manufacturing polymer products with a sandwich structure or a hollow structure. Typically, two different materials are injected or transferred into a mold sequentially or simultaneously. The skin is generally a prime polymer with required surface and bulk properties for intended use. The core can be solid, foam or gas. Obtaining a uniform encapsulated structure is difficult and there are no science-based rules for optimization of process setup. Thus, a physical model and process simulations have been developed based on the kinematics and dynamics of a moving interface, and Hele-Shaw approximation. The model has incorporated temperature and shear rate dependences of viscosity of both skin and core component into the transient interface evolution. Based on the developed model, simulations have been carried out to study flow rate controlled simultaneous co-injection molding of thermoplastics, pressure-controlled sequential transfer molding of rubber compounds, and gas-assisted injection molding (GAIM). The simulation results were compared with the experimental data, and in general, good agreement was found between the predicted and experimentally measured interface distribution in moldings. For simultaneous co-injection molding, it is found that material pairs with a broad range of viscosities may be utilized. Breakthrough phenomena are mainly determined by the volume of melt of initial single phase injection and rheological properties of material combinations. When the core has a lower viscosity than the skin, or the volume of initial injection of skin melt is smaller, breakthrough is very likely. However, the breakthrough can be eliminated by controlling injection rate of the skin and core melts. For sequential transfer molding, it is found that the rubber distribution in moldings are dominated by the rheological properties of components and the volume fraction transferred, but independent of the gate pressure. When the

  17. Flexible free-standing luminescent two-component fiber films with tunable hierarchical structures based on hydrogen-bonding architecture.

    Science.gov (United States)

    Yan, Dongpeng; Williams, Gareth R; Zhao, Min; Li, Changming; Fan, Guoling; Yang, Hejia

    2013-12-17

    Although the fabrication of hierarchical architectures with highly ordered functional units is of great importance for both fundamental science and practical application, the development of one-dimensional (1D) organic hierarchical micro/nanostructures based on low-molecular-weight (LMW) building blocks remains at an early stage. Herein, we report two types of micro/nanoscaled multicomponent fluorescent fiber systems with tunable hierarchical morphologies through a one-step coassembly process. With the aid of hydrogen-bonding motifs, LMW precursors (1,4-bis(5-phenyloxazol-2-yl)benzene (A) and two coassembled building blocks: 4-bromotetrafluorobenzene carboxylic acid (B) and 2,3,4,5,6-pentafluorophenol (C)) have been self-organized into fibers and flexible free-standing films, which show hierarchical micro/nanostructures as well as tunable one-/two-photon luminescence. The disassembly of the multicomponent A.B and A.C fibers occurs at high temperature, which further alters the luminescence properties of the multicomponent materials. Therefore, this work provides a facile wet chemical route for fabricating multicomponent LMW self-assembled fibers and free-standing film systems with tunable hierarchical structures and photoemission behaviors, and such self-organized systems may have potential applications in fields of two-photon luminescence and thermal sensors. PMID:24274340

  18. Ultrasonic relaxation study of preferential solvation in quasi-two-components aqueous solutions of amides and zinc salts.

    Science.gov (United States)

    Miecznik, P; Golebiewski, Z

    2004-04-01

    To investigate the effect of preferential solvation the ultrasonic attenuation (2-50 MHz) and velocities (3 MHz) of ZnCl(2) and 2-chloroacetamide (ClCH(2)CONH(2)) in water and its quasi-binary mixtures with the ratio (ZnCl(2)+ClCH(2)CONH(2)):H(2)O=1:55 at 298.15 K have been measured. The creation of specific complexes in the ClCH(2)CONH(2)-H(2)O-ZnCl(2) system have a relaxational character which, within the measurements of ultrasonic absorption in the frequency range 2-50 MHz, have been observed. On the base of these properties the kinetic and dynamic parameters of the observed relaxation have been calculated. To bring into relief the influence of Cl atom in the 2-chloroacetamide molecules for complexation process it has been investigated also the system AA-H(2)O-ZnCl(2). The next step of searching was to investigate the system of CHAA-H(2)O-ZnBr(2), to reduce the influence of Cl atom within ZnCl(2) molecule at the complexation process. The main aim of presented study was to investigate the possibility of complexation in the aqueous solutions of ZnCl(2) with the part of 2-ClCH(2)CONH(2) (CHAA). With regard of big complexing ability of zinc, there exist a theoretical possibility of attachment CHAA to the inner coordination sphere of zinc through chloride atom. There can create here outer-sphere as well as inner-sphere complexes. As a results the observed relaxation processes have been attributed to creation and disintegration the following complexes: Zn(H(2)O)(2)(CHAA)(4)(2+) and Zn(2+)(H(2)O)(3)(CHAA)Cl(2)(-). PMID:15047358

  19. Novel two-component transmembrane transcription control: regulation of iron dicitrate transport in Escherichia coli K-12.

    OpenAIRE

    Van Hove, B; Staudenmaier, H; Braun, V

    1990-01-01

    Citrate and iron have to enter only the periplasmic space in order to induce the citrate-dependent iron(III) transport system of Escherichia coli. The five transport genes fecABCDE form an operon and are transcribed from fecA to fecE. Two genes, termed fecI and fecR, that mediate induction by iron(III) dicitrate have been identified upstream of fecA. The fecI gene encodes a protein of 173 amino acids (molecular weight, 19,478); the fecR gene encodes a protein of 317 amino acids (molecular wei...

  20. A new pair of hard-soft plastic combination for precision manufacturing of two component plastic parts

    DEFF Research Database (Denmark)

    Islam, Aminul; Hansen, Hans Nørgaard; Marhöfer, David Maximilian;

    2011-01-01

    was lack of sealing between the Plug-Socket combination so, corrosive agents like human sweat, oil and dirt could corrode the contact pins inside the Socket house. The new design of the Socket is an improvement of the old design which contains a micro sealing ring. This 2k micro part was moulded by...... block copolymers (TPE-S). By using this pair of materials, a demonstrator 2k micro part (Socket house for hearing aid) has been fabricated. This kind of socket is used in Receiver-in-the-canal hearing aid system to connect the receiver with hearing aid processors. The problem with the previous design...... socket house and precisely detect the pressure developed inside the socket house and finally could detect the leak of the fluid due to the sealing ring leakage. All the test procedures and results presented in this paper can be a valuable source of information for researchers and scientists who work with...

  1. Two-component injection mould for automobile ventilation cover plate%汽车通风盖板双色注射模设计

    Institute of Scientific and Technical Information of China (English)

    董磊磊; 张惠敏

    2014-01-01

    以汽车通风盖板为例介绍一种新型双色注射模,模具采用封刀片结构可以避免传统的双色注射动模旋转带来的不便,同时能使模具尺寸减少、加工制造简单。实际生产证明,模具生产的塑件外观精致,硬塑料和软塑料结合的部位满足客户要求。%A new two-component injection mould for an automobile ventilation cover plate was developed in which sealing blade structure was adopted that can avoid the inconve-nience of traditional two-component injection mould in rotating; the mould size is reduced and the processing and manufacturing are simplified.

  2. Phase separation of a two-component dipolar Bose-Einstein condensate in the quasi-one-dimensional and quasi-two-dimensional regime

    International Nuclear Information System (INIS)

    We consider a two-component Bose-Einstein condensate, which contains atoms with magnetic dipole moments aligned along the z direction (labeled as component 1) and nonmagnetic atoms (labeled as component 2). The problem is studied by means of exact numerical simulations. The effects of dipole-dipole interaction on phase separations are investigated. It is shown that, in the quasi-one-dimensional regime, the atoms in component 2 are squeezed out when the dimensionless dipolar strength parameter is small, whereas the atoms in component 1 are pushed out instead when the parameter is large. This is in contrast to the phenomena in the quasi-two-dimensional regime. These two components are each kicked out by the other in the quasi-one-dimensional regime and this phenomenon is discussed as well.

  3. Boundary-induced bulk phase transition and violation of Fick's law in two-component single-file diffusion with open boundaries

    OpenAIRE

    Brzank, Andreas; Schütz, Gunter M.

    2006-01-01

    We study two-component single-file diffusion inside a narrow channel that at its ends is open and connected with particle reservoirs. Using a two-species version of the symmetric simple exclusion process as a model, we propose a hydrodynamic description of the coarse-grained dynamics with a self-diffusion coefficient that is inversely proportional to the length of the channel. The theory predicts an unexpected nonequilibrium phase transition for the bulk particle density as the external total...

  4. Phase diffusion of a two-component Bose–Einstein condensates: exact and short-time solutions for arbitrary coherent spin state

    International Nuclear Information System (INIS)

    We investigate phase diffusion of a two-component Bose–Einstein condensates prepared initially in arbitrary coherent spin state |θ0, φ0). Analytical expression of the phase-diffusion time is presented for θ0 ≠ π/2 case. In comparison with the symmetrical case (i.e., θ0 = π/2), we find that the diffusion process becomes slow due to the reduced atom number variance. (general)

  5. Role of Streptococcus pyogenes Two-Component Response Regulators in the Temporal Control of Mga and the Mga-Regulated Virulence Gene emm

    OpenAIRE

    Ribardo, Deborah A.; Lambert, Thomas J.; McIver, Kevin S.

    2004-01-01

    We examined the role of Streptococcus pyogenes two-component response regulators (SptR) in expression of Mga and the Mga-regulated gene emm. Both serotype M6 and serotype M1 mutants in 12 of the 13 identified sptR genes exhibited levels of emm transcripts and Mga protein comparable to those of the wild type during exponential and stationary phases of growth. Thus, temporal control of these virulence genes does not require Spt response regulators.

  6. Internal Josephson-like tunnelling in two-component Bose-Einstein condensates affected by sign of the atomic interaction and external trapping potential

    Institute of Scientific and Technical Information of China (English)

    Xiong Bo; Liu Xun-Xu

    2007-01-01

    This paper studies the Josephson-like tunnelling in two-component Bose-Einstein condensates coupled with microwave field, which is in respond to various attractive and repulsive atomic interaction under the various aspect ratio of trapping potential. It is very interesting to find that the dynamic of Josephson-like tunnelling can be controlled from fast damped oscillations to nondamped oscillation, and relative number of atoms changes from asymmetric occupation to symmetric occupation correspondingly.

  7. A two-component dark matter model with real singlet scalars confronting GeV -ray excess from galactic centre and Fermi bubble

    Indian Academy of Sciences (India)

    Debasish Majumdar; Kamakshya Prasad Modak; Subhendu Rakshit

    2016-02-01

    We propose a two-component dark matter (DM) model, each component of which is a real singlet scalar, to explain results from both direct and indirect detection experiments. We put the constraints on the model parameters from theoretical bounds, PLANCK relic density results and direct DM experiments. The -ray flux is computed from DM annihilation in this framework and is then compared with the Fermi-LAT observations from galactic centre region and Fermi bubble.

  8. Effects of the Acrylic Polyol Structure and the Selectivity of the Employed Catalyst on the Performance of Two-component Aqueous Polyurethane Coatings

    OpenAIRE

    Miladin Gligoric; Miroljub Barac; Ljiljana Takic; Nikola Ristic; Jakov Stamenkovic; Caslav Lacnjevac; Suzana Cakic

    2007-01-01

    Two kinds of aqueous acrylic polyols (single step and multi step synthesis type) have been investigated for their performance in the two-component aqueous polyurethane application, by using more selective catalysts. The aliphatic polyfunctional isocyanates based on hexamethylen diisocyanates have been employed as suitable hardeners. The complex of zirconium, commercially known as K-KAT®XC-6212, and manganese (III) complexes with mixed ligands based on the derivative of maleic acid have been u...

  9. 双组分聚氨酯道桥密封膏的研制%The Research of Two-Component Polyurethane Sealant for Road and Bridge

    Institute of Scientific and Technical Information of China (English)

    孙金梅; 段文锋; 王小雪

    2011-01-01

    以聚醚多元醇、甲苯二异氰酸酯(TDI)、扩链剂、填料、复合催化剂、增塑剂、触变剂为主要原料,制备了一种低模量、高弹性、高粘接力的双组分聚氨酯道桥密封膏,讨论了影响该密封膏性能的因素.结果表明,当异氰酸酯指数在1.0~1.35、复合催化剂用量在0.9% ~1.1%、触变剂用量为10%~12%、活性轻钙用量为18% ~21%时,制备的密封膏的拉伸模量、下垂度、可施工时间、表干时间、弹性等性能较佳.同时通过采用自制的复合催化剂体系,利用化学增稠的方法解决了搅拌速度低对生产设备带来的问题,获得了性能优异的产品.%A low modulus, high elasticity, high bonding of two-component polyurethane sealant which were applied to road and bridge was prepared mainly from polyether polyol, toluene isocyanate, chain extender, padding, plasticizer and thixotropic agent. The affecting factors on the sealant performances were discussed. The results showed that the performance of sealant including tensile modulus, sag, construction time, dry time and flexibility were better when the isocyanate index (R) was from 1.0 to 1.35, the composite catalyst dosage was 0.9% to 1. 1% , the thixotropic agent dosage was 10% to 12% , the activity light calcium dosage was 18% to 21%. At the same time, the problems of production and performance that were caused by low speed mixing equipment were solved and excellent performance of product was obtained by using self-made compound catalyst system and chemical thickening.

  10. Magnetization damping in two-component metal oxide micropowder and nanopowder compacts by broadband ferromagnetic resonance measurements

    Science.gov (United States)

    Youssef, Jamal Ben; Brosseau, Christian

    2006-12-01

    The microwave damping mechanisms in magnetic inhomogeneous systems have displayed a richness of phenomenology that has attracted widespread interest over the years. Motivated by recent experiments, we report an extensive experimental study of the Gilbert damping parameter of multicomponent metal oxides micro- and nanophases. We label the former by M samples, and the latter by N samples. The main thrust of this examination is the magnetization dynamics in systems composed of mixtures of magnetic (γ-Fe2O3) and nonmagnetic (ZnO and epoxy resin) materials fabricated via powder processing. Detailed ferromagnetic resonance (FMR) measurements on N and M samples are described so to determine changes in the microwave absorption over the 6-18GHz frequency range as a function of composition and static magnetic field. The FMR linewidth and the field dependent resonance were measured for the M and N samples, at a given volume fraction of the magnetic phase. The asymmetry in the form and change in the linewidth for the M samples are caused by the orientation distribution of the local anisotropy fields, whereas the results for the N samples suggest that the linewidth is very sensitive to details of the spatial magnetic inhomogeneities. For N samples, the peak-to-peak linewidth increases continuously with the volume content of magnetic material. The influence of the volume fraction of the magnetic phase on the static internal field was also investigated. Furthermore, important insights are gleaned through analysis of the interrelationship between effective permeability and Gilbert damping constant. Different mechanisms have been considered to explain the FMR linewidth: the intrinsic Gilbert damping, the broadening induced by the magnetic inhomogeneities, and the extrinsic magnetic relaxation. We observed that the effective Gilbert damping constant of the series of N samples are found to be substantially smaller in comparison to M samples. This effect is attributed to the surface

  11. Effects of the Acrylic Polyol Structure and the Selectivity of the Employed Catalyst on the Performance of Two-component Aqueous Polyurethane Coatings

    Directory of Open Access Journals (Sweden)

    Miladin Gligoric

    2007-03-01

    Full Text Available Two kinds of aqueous acrylic polyols (single step and multi step synthesis typehave been investigated for their performance in the two-component aqueous polyurethaneapplication, by using more selective catalysts. The aliphatic polyfunctional isocyanatesbased on hexamethylen diisocyanates have been employed as suitable hardeners. Thecomplex of zirconium, commercially known as K-KAT®XC-6212, and manganese (IIIcomplexes with mixed ligands based on the derivative of maleic acid have been used ascatalysts in this study. Both of the aqueous polyols give good results, in terms of applicationand hardness, when elevated temperatures and more selective catalysts are applied. A moreselective catalyst promotes the reaction between the isocyanate and polyol component. Thisincreases the percentage of urethane bonds and the degree of hardness in the films formedfrom the two components of aqueous polyurethane lacquers. The polyol based on the singlestep synthesis route is favourable concerning potlife and hardness. The obtained resultsshow that the performance of the two-component aqueous polyurethane coatings depends onthe polymer structure of the polyols as well as on the selectivity of the employed catalyst.

  12. Novel two-component transmembrane transcription control: regulation of iron dicitrate transport in Escherichia coli K-12.

    Science.gov (United States)

    Van Hove, B; Staudenmaier, H; Braun, V

    1990-12-01

    Citrate and iron have to enter only the periplasmic space in order to induce the citrate-dependent iron(III) transport system of Escherichia coli. The five transport genes fecABCDE form an operon and are transcribed from fecA to fecE. Two genes, termed fecI and fecR, that mediate induction by iron(III) dicitrate have been identified upstream of fecA. The fecI gene encodes a protein of 173 amino acids (molecular weight, 19,478); the fecR gene encodes a protein of 317 amino acids (molecular weight, 35,529). Chromosomal fecI::Mu d1 mutants were unable to grow with iron(III) dicitrate as the sole iron source and synthesized no FecA outer membrane receptor protein. Growth was restored by transformation with plasmids encoding fecI or fecI and fecR. FecA and beta-galactosidase syntheses under transcription control of the fecB gene (fecB::Mu d1) were constitutive in fecI transformants and were regulated by iron(III) dicitrate in fecI fecR transformants. The amino acid sequence of the FecI protein contains a region close to the carboxy-terminal end for which a helix-turn-helix motif is predicted, which is typical for DNA-binding regulatory proteins. The FecI protein was found in the membrane, and the FecR protein was found in the periplasmic fraction. It is proposed that the FecR protein is the sensor that recognizes iron(III) dicitrate in the periplasm. The FecI protein activates fec gene expression by binding to the fec operator region. In the absence of citrate, FecR inactivates FecI. The lack of sequence homologies to other transmembrane signaling proteins and the location of the two proteins suggest a new type of transmembrane control mechanism. PMID:2254251

  13. 双组份涂料机理及其防水效果探究%Mechanism of Two-component Coatings and Its Waterproofing Effect

    Institute of Scientific and Technical Information of China (English)

    许荣章

    2011-01-01

    目前公路建设、公路养护等普遍采用新型的双组份涂料,双组份涂料以其施工简便、干燥迅速、防水效果好等优点备受各涂料消耗行业青睐.但是随着我国经济的发展,涂料业也如雨后春笋般迅速成长,大大小小的涂料品牌,多种多样的涂料品种混杂在一起使消费者难以辨别.而在众多涂料种类中消费者最常用到的就是防水双组份涂料,由于市场的双组份防水涂料种类繁多,消费者对其作用机理又不是很了解,所以在选购时很难着手.本文就将就这一问题做深入细致的讨论,一方面阐述双足分涂料的作用机理,另一方面分析一下市场状况,为消费这或者企业在选购时提供一些参考.%Current road construction and road maintenance widely use new two-component coatings. For its advantages of simple construction, quick drying, good waterproof effect, two-component coating get much favor of paint industry consumes. But as China's economic development, paint industry has grew rapidly, large and small paint brands and kinds of paint make consumers be difficult to distinguish. In many types of paint, two-component coating is most common kind. Because there are varieties of two-component waterproof coating in market, the consumers do not very understand its role,so it is difficult to purchase. This paper will discuss this issue in depth, on the one hand describes the role mechanism of two-component waterproof coating, on the other hand analyzes the market situation, to provide some reference for the consumer and business.

  14. A Two-Component DNA-Prime/Protein-Boost Vaccination Strategy for Eliciting Long-Term, Protective T Cell Immunity against Trypanosoma cruzi

    OpenAIRE

    Shivali Gupta; Garg, Nisha J.

    2015-01-01

    In this study, we evaluated the long-term efficacy of a two-component subunit vaccine against Trypanosoma cruzi infection. C57BL/6 mice were immunized with TcG2/TcG4 vaccine delivered by a DNA-prime/Protein-boost (D/P) approach and challenged with T. cruzi at 120 or 180 days post-vaccination (dpv). We examined whether vaccine-primed T cell immunity was capable of rapid expansion and intercepting the infecting T. cruzi. Our data showed that D/P vaccine elicited CD4+ (30-38%) and CD8+ (22-42%) ...

  15. Miscibility of Two Components in a Binary Mixture of 9-Phenyl Anthracene Mixed with Stearic Acid or Polymethyl Methacrylate at Air-Water Interface

    Institute of Scientific and Technical Information of China (English)

    P. K. Paul; Md. N. Islam; D. Bhattacharjee; S. A. Hussain

    2007-01-01

    We report the miscibility characteristics of two components in a binary mixture of 9-phenyl anthracene (PA) mixed with stearic acid (SA) or polymethyl methacrylate (PMMA). The behaviour of surface pressure versus area per molecule isotherms reveal that the area per molecule decreases systematically with increasing molefractions of PA. The characteristics of areas per molecule versus molefractions and collapse pressure vs molefraction indicate that various interactions involved among the sample and matrix molecules. The interaction scheme is found to change with the change in surface pressure and molefraction of mixing. Scanning electron microscopic study confirms the aggregation of PA molecules in the mixed films.

  16. 滑动型芯式双色注射模设计%Design of two-component injection mould with sliding core

    Institute of Scientific and Technical Information of China (English)

    董磊磊; 杜龙女

    2014-01-01

    介绍了一种滑动型芯式双色注射模,阐述了模具设计要点。模具采用第1次注射硬塑料熔体,第2次注射软塑料熔体的方式进行生产,相比传统旋转型芯式双色注射模,能在生产大型双色塑件时减少模具外形尺寸,降低对注塑机空间的要求,节省模具制造成本,提高塑件生产效率。%The design points of a two-component injection mould with sliding core for a scroll-shaped cover was presented. The rigid and flexible plastic melt was injected respec-tively in the first and second run which can reduce the mould outline dimensions and de-mands for the space of injection moulding machine in manufacturing large scale two-compo-nent plastic parts, compared to traditional two-component injection mould with rotating core.

  17. Determination of Bisphenol A and Bisphenol AF in Vinegar samples by two-component mixed ionic liquid dispersive liquid-phase microextraction coupled with high performance liquid chromatography

    International Nuclear Information System (INIS)

    This paper describes a sensitive and simple method for the determination of bisphenol A (BPA) and bisphenol AF (BPAF) in vinegar samples using two-component mixed ionic liquid dispersive liquid-phase microextraction coupled with high performance liquid chromatography. In this work, BPA and BPAF were selected as the model analytes, and two-component mixed ionic liquid included 1-butyl-3-methylimidazolium hexafluorophosphate ((C4Mim)PF6) and 1-hexyl-3-methyl-imidazolium hexafluorophosphate ((C6Mim)PF6) was used as the extraction solvent for the first time here. Parameters that affect the extraction efficiency were investigated. Under the optimum conditions, good linear relationships were discovered in the range of 1.0-100 micro g/L for BPA and 2.0-150 micro g/L for BPAF, respectively. Detection limits of proposed method based on the signal-to-noise ratio (S/N=3) were in the range of 0.15-0.38 micro g/L. The efficiencies of proposed method have also been demonstrated with spiked real vinegar samples. The result show this method/ procedure to be a more efficient approach for the determination of BPA and BPAF in real vinegar, presenting average recovery rate of 89.3-112 % and precision values of 0.9-13.5% (RSDs, n = 6). In comparison with traditional solid phase extraction procedures this method results in lower solvent consumption, low pollution levels, and faster sample preparation. (author)

  18. AN ENTROPIC ORDER QUANTITY MODEL WITH FUZZY HOLDING COST AND FUZZY DISPOSAL COST FOR PERISHABLE ITEMS UNDER TWO COMPONENT DEMAND AND DISCOUNTED SELLING PRICE

    Directory of Open Access Journals (Sweden)

    P.K. Tripathy

    2008-07-01

    Full Text Available A new type of replenishment policy is suggested in an entropy order quantity model for a perishable product possessing fuzzy holding cost and fuzzy disposal cost. This model represents an appropriate combination of two component demand with discounted selling price, particularly over a finite time horizon. Its main aim lies in the need for an entropic cost of the cycle time is a key feature of specific perishable product like fruits, vegetables, food stuffs, fishes etc. To handle this multiplicity of objectives in a pragmatic approach, entropic ordering quantity model with discounted selling price during pre and post deterioration of perishable items to optimize its payoff is proposed. It has been imperative to demonstrate this model by analysis, which reveals some important characteristics of discounted structure. Furthermore, numerical experiments are conducted to evaluate the difference between the crisp and fuzzy cases in EOQ and EnOQ separately. This paper explores the economy of investing in economics of lot sizing in Fuzzy EOQ, Crisp EOQ and Crisp EnOQ models. The proposed paper reveals itself as a pragmatic alternative to other approaches based on two component demand function with very sound theoretical underpinnings but with few possibilities of actually being put into practice. The results indicate that this can become a good model and can be replicated by researchers in neighbourhood of its possible extensions.

  19. The Two-Component Quantum Theory of Atoms in Molecules (TC-QTAIM): The unified theory of localization/delocalization of electrons, nuclei and exotic elementary particles

    CERN Document Server

    Goli, Mohammad

    2013-01-01

    In this contribution, pursuing our research program extending the atoms in molecules analysis into unorthodox domains, another key ingredient of the two-component quantum theory of atoms in molecules (TC-QTAIM) namely, the theory of localization/delocalization of quantum particles, is disclosed. The unified proposed scheme is able not only to deal with the localization/delocalization of electrons in/between atomic basins, but also to treat nuclei as well as exotic particles like positrons and muons equally. Based on the general reduced second order density matrices for indistinguishable quantum particles, the quantum fluctuations of atomic basins are introduced and then used as a gauge to quantify the localization/delocalization introducing proper indexes. The explicit mass-dependence of the proposed indexes is demonstrated and it is shown that a single localization/delocalization index is capable of being used for all kind of quantum particles regardless of their masses or charge content. For various non-Bor...

  20. Dose- and time-dependent changes of micronucleus frequency and gene expression in the progeny of irradiated cells: Two components in radiation-induced genomic instability?

    Energy Technology Data Exchange (ETDEWEB)

    Huumonen, Katriina [University of Eastern Finland, Department of Environmental Science, P.O. Box 1627, 70211 Kuopio (Finland); Korkalainen, Merja [National Institute for Health and Welfare, Department of Environmental Health, P.O. Box 95, 70701 Kuopio (Finland); Boman, Eeva; Heikkilä, Janne [Kuopio University Hospital, Cancer Center, P.O. Box 1777, 70211 Kuopio (Finland); Höytö, Anne [University of Eastern Finland, Department of Environmental Science, P.O. Box 1627, 70211 Kuopio (Finland); Lahtinen, Tapani [Kuopio University Hospital, Cancer Center, P.O. Box 1777, 70211 Kuopio (Finland); Luukkonen, Jukka [University of Eastern Finland, Department of Environmental Science, P.O. Box 1627, 70211 Kuopio (Finland); Viluksela, Matti [National Institute for Health and Welfare, Department of Environmental Health, P.O. Box 95, 70701 Kuopio (Finland); Naarala, Jonne [University of Eastern Finland, Department of Environmental Science, P.O. Box 1627, 70211 Kuopio (Finland); Juutilainen, Jukka, E-mail: jukka.juutilainen@uef.fi [University of Eastern Finland, Department of Environmental Science, P.O. Box 1627, 70211 Kuopio (Finland)

    2014-07-15

    Highlights: • Development with time of radiation-induced genomic instability (RIGI) was studied. • Dose–response of micronuclei showed marked time-dependent changes. • A new model assuming two components in RIGI was found to fit with the data. • The persisting component of RIGI seems to be independent of dose above a threshold. • Increasing heterogeneity was characteristic to delayed gene expression changes. - Abstract: Murine embryonic C3H/10T½ fibroblasts were exposed to X-rays at doses of 0.2, 0.5, 1, 2 or 5 Gy. To follow the development of radiation-induced genomic instability (RIGI), the frequency of micronuclei was measured with flow cytometry at 2 days after exposure and in the progeny of the irradiated cells at 8 and 15 days after exposure. Gene expression was measured at the same points in time by PCR arrays profiling the expression of 84 cancer-relevant genes. The micronucleus results showed a gradual decrease in the slope of the dose–response curve between days 2 and 15. The data were consistent with a model assuming two components in RIGI. The first component is characterized by dose-dependent increase in micronuclei. It may persist more than ten cell generations depending on dose, but eventually disappears. The second component is more persistent and independent of dose above a threshold higher than 0.2 Gy. Gene expression analysis 2 days after irradiation at 5 Gy showed consistent changes in genes that typically respond to DNA damage. However, the consistency of changes decreased with time, suggesting that non-specificity and increased heterogeneity of gene expression are characteristic to the second, more persistent component of RIGI.

  1. Two-component model in quantum statistical framework compared with multiplicity distributions in proton-proton collisions at energies up to {radical}(s)=7 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Premomoy, E-mail: prem@vecc.gov.in [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700 064 (India)

    2011-11-17

    Proton-proton collisions at new high energies ({radical}(s)=2.36 and 7 TeV) at LHC resulted into greater mean multiplicities (Left-Pointing-Angle-Bracket n Right-Pointing-Angle-Bracket) of charged particles in the mid-rapidity region than estimated ones by different models and event generators. Another significant observation in multiplicity data is the change in slope in the distribution of primary charged hadrons in symmetric pseudorapidity interval |{eta}|<2.4. The change is most prominent with data at {radical}(s)=7 TeV. These new observations merit further studies. We consider a two-component model of particle production to analyze multiplicity distributions of charged hadrons from proton-proton collisions at centre-of-mass energies {radical}(s)=0.9, 2.36 and 7 TeV in symmetric pseudorapidity intervals |{eta}| of increasing width around the centre-of-mass pseudorapidity {eta}{sub cm}=0. The model, based on Quantum Statistical (QS) formalism, describes multiplicity distribution by convolution of a Negative Binomial Distribution (NBD), representing a chaotic component, and a Poisson Distribution (PD), representing a coherent component of particle productions. The behaviour of characteristic parameters of the model is followed by the LHC data, while a scaling law, involving information entropy in quantum statistical viewpoint and derived as a function of chaotic multiplicity obtained from the two-component model, is not obeyed by the data, satisfactorily. An attempt to match the measured multiplicity distributions and suggested convolutions with values of characteristic parameters extracted from the data confirms disagreement between the data and the model.

  2. Dose- and time-dependent changes of micronucleus frequency and gene expression in the progeny of irradiated cells: Two components in radiation-induced genomic instability?

    International Nuclear Information System (INIS)

    Highlights: • Development with time of radiation-induced genomic instability (RIGI) was studied. • Dose–response of micronuclei showed marked time-dependent changes. • A new model assuming two components in RIGI was found to fit with the data. • The persisting component of RIGI seems to be independent of dose above a threshold. • Increasing heterogeneity was characteristic to delayed gene expression changes. - Abstract: Murine embryonic C3H/10T½ fibroblasts were exposed to X-rays at doses of 0.2, 0.5, 1, 2 or 5 Gy. To follow the development of radiation-induced genomic instability (RIGI), the frequency of micronuclei was measured with flow cytometry at 2 days after exposure and in the progeny of the irradiated cells at 8 and 15 days after exposure. Gene expression was measured at the same points in time by PCR arrays profiling the expression of 84 cancer-relevant genes. The micronucleus results showed a gradual decrease in the slope of the dose–response curve between days 2 and 15. The data were consistent with a model assuming two components in RIGI. The first component is characterized by dose-dependent increase in micronuclei. It may persist more than ten cell generations depending on dose, but eventually disappears. The second component is more persistent and independent of dose above a threshold higher than 0.2 Gy. Gene expression analysis 2 days after irradiation at 5 Gy showed consistent changes in genes that typically respond to DNA damage. However, the consistency of changes decreased with time, suggesting that non-specificity and increased heterogeneity of gene expression are characteristic to the second, more persistent component of RIGI

  3. The VirS/VirR Two-Component System Regulates the Anaerobic Cytotoxicity, Intestinal Pathogenicity, and Enterotoxemic Lethality of Clostridium perfringens Type C Isolate CN3685

    OpenAIRE

    Ma, Menglin; Vidal, Jorge; Saputo, Juliann; McClane, Bruce A.; Uzal, Francisco

    2011-01-01

    Clostridium perfringens vegetative cells cause both histotoxic infections (e.g., gas gangrene) and diseases originating in the intestines (e.g., hemorrhagic necrotizing enteritis or lethal enterotoxemia). Despite their medical and veterinary importance, the molecular pathogenicity of C. perfringens vegetative cells causing diseases of intestinal origin remains poorly understood. However, C. perfringens beta toxin (CPB) was recently shown to be important when vegetative cells of C. perfringens...

  4. Development, Evaluation, and Validation of a Paper-and-Pencil Test for Measuring Two Components of Biology Teachers' Pedagogical Content Knowledge Concerning the "Cardiovascular System"

    Science.gov (United States)

    Schmelzing, Stephan; van Driel, Jan H.; Jüttner, Melanie; Brandenbusch, Stefanie; Sandmann, Angela; Neuhaus, Birgit J.

    2013-01-01

    One main focus of teacher education research concentrates on teachers' pedagogical content knowledge (PCK). It has been shown that teachers' PCK correlates with teaching effectiveness as well as with students' achievement gains. Teachers' PCK should be analyzed as one of the main important components to evaluate professional…

  5. Mechanisms underlying zoonotic success of Campylobacter jejuni: the CprRS two-component regulatory system influences essential processes, biofilm formation, and pathogenesis

    Science.gov (United States)

    Campylobacter jejuni is a leading cause of food- and waterbourne bacterial gastroenteritis in the developed world. Although illness is usually self-limiting, immunocompromised individuals are at risk for infections recalcitrant to antibiotic treatment, and prior campylobacter infection correlates wi...

  6. The Eukaryotic-Like Ser/Thr Kinase PrkC Regulates the Essential WalRK Two-Component System in Bacillus subtilis

    OpenAIRE

    Libby, Elizabeth A.; Goss, Lindsie A.; Jonathan Dworkin

    2015-01-01

    Most bacteria contain both eukaryotic-like Ser/Thr kinases (eSTKs) and eukaryotic-like Ser/Thr phosphatases (eSTPs). Their role in bacterial physiology is not currently well understood in large part because the conditions where the eSTKs are active are generally not known. However, all sequenced Gram-positive bacteria have a highly conserved eSTK with extracellular PASTA repeats that bind cell wall derived muropeptides. Here, we report that in the Gram-positive bacterium Bacillus subtilis, th...

  7. Crystallization and preliminary X-ray crystallographic studies of DesR, a thermosensing response regulator in a two-component signalling system from Streptococcus pneumoniae

    International Nuclear Information System (INIS)

    The response regulator DesR from S. pneumoniae was cloned, expressed, purified and crystallized. A complete data set was collected to 1.7 Å resolution. The response regulator DesR, which activates the transcription of the des gene by binding to a regulatory region, is essential for controlling the fluidity of membrane phospholipids. DesR from Streptococcus pneumoniae was overexpressed in Escherichia coli. The protein was purified and crystallized for structural analysis. Diffraction data were collected to 1.7 Å resolution using synchrotron radiation and the crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 46.91, b = 71.38, c = 117.73 Å. Assuming the presence of a dimer in the asymmetric unit, this corresponds to a VM of 2.21 Å3 Da−1

  8. Two-component model in quantum statistical framework compared with multiplicity distributions in proton-proton collisions at energies up to $\\sqrt {s}$ = 7 TeV

    CERN Document Server

    Ghosh, Premomoy

    2012-01-01

    Proton-proton collisions at new high energies ($\\sqrt {s} =$ 2.36 and 7 TeV) at LHC resulted into greater mean multiplicities ($$) of charged particles in the mid-rapidity region than estimated ones by different models and event generators. Another significant observation in multiplicity data is the change in slope in the distribution of primary charged hadrons in symmetric pseudorapidity interval $|\\eta|<$2.4. The change is most prominent with data at $\\sqrt{s} = 7$ TeV. These new observations merit further studies. We consider a two-component model of particle production to analyze multiplicity distributions of charged hadrons from proton-proton collisions at centre-of-mass energies $\\sqrt{s} = $ 0.9, 2.36 and 7 TeV in symmetric pseudorapidity intervals $|\\eta|$ of increasing width around the centre-of-mass pseudorapidity $\\eta_{cm} = 0$. The model, based on quantum statistical (QS) formalism, describes multiplicity distribution by convolution of a Negative Binomial Distribution (NBD), representing a cha...

  9. Two-component model in quantum statistical framework compared with multiplicity distributions in proton-proton collisions at energies up to √{ s} = 7 TeV

    Science.gov (United States)

    Ghosh, Premomoy

    2011-11-01

    Proton-proton collisions at new high energies (√{ s} = 2.36 and 7 TeV) at LHC resulted into greater mean multiplicities () of charged particles in the mid-rapidity region than estimated ones by different models and event generators. Another significant observation in multiplicity data is the change in slope in the distribution of primary charged hadrons in symmetric pseudorapidity interval | η | distributions of charged hadrons from proton-proton collisions at centre-of-mass energies √{ s} = 0.9, 2.36 and 7 TeV in symmetric pseudorapidity intervals | η | of increasing width around the centre-of-mass pseudorapidity ηcm = 0. The model, based on Quantum Statistical (QS) formalism, describes multiplicity distribution by convolution of a Negative Binomial Distribution (NBD), representing a chaotic component, and a Poisson Distribution (PD), representing a coherent component of particle productions. The behaviour of characteristic parameters of the model is followed by the LHC data, while a scaling law, involving information entropy in quantum statistical viewpoint and derived as a function of chaotic multiplicity obtained from the two-component model, is not obeyed by the data, satisfactorily. An attempt to match the measured multiplicity distributions and suggested convolutions with values of characteristic parameters extracted from the data confirms disagreement between the data and the model.

  10. Quasi-Periodic Variations in X-ray Emission and Long-Term Radio Observations: Evidence for a Two-Component Jet in Sw J1644+57

    CERN Document Server

    Wang, Jiu-Zhou; Wang, Ding-Xiong; Zou, Yuan-Chuan; Zhang, Bing; Gao, He; Huang, Chang-Yin

    2014-01-01

    The continued observations of Sw J1644+57 in X-ray and radio bands accumulated a rich data set to study the relativistic jet launched in this tidal disruption event. The X-ray light curve of Sw J1644+57 from 5-30 days presents two kinds of quasi-periodic variations: a 200 second quasi-periodic oscillation (QPO) and a 2.7-day quasi-periodic variation. The latter has been interpreted by a precessing jet launched near the Bardeen-Petterson radius of a warped disk. Here we suggest that the $\\sim$ 200s QPO could be associated with a second, narrower jet sweeping the observer line-of-sight periodically, which is launched from a spinning black hole in the misaligned direction with respect to the black hole's angular momentum. In addition, we show that this two-component jet model can interpret the radio light curve of the event, especially the re-brightening feature starting $\\sim 100$ days after the trigger. From the data we infer that inner jet may have a Lorentz factor of $\\Gamma_{\\rm j} \\sim 5.5$ and a kinetic e...

  11. Effects of Compton Cooling on the Hydrodynamic and the Spectral Properties of a Two Component Accretion Flow around a Black Hole

    CERN Document Server

    Ghosh, Himadri; Giri, Kinsuk; Chakrabarti, Sandip K

    2011-01-01

    We carry out a time dependent numerical simulation where both the hydrodynamics and the radiative transfer are coupled together. We consider a two-component accretion flow in which the Keplerian disk is immersed inside an accreting low angular momentum flow (halo) around a black hole. The injected soft photons from the Keplerian disk are reprocessed by the electrons in the halo. We show that in presence of an axisymmetric soft-photon source, the spherically symmetric Bondi flow losses its symmetry and becomes axisymmetric. The low angular momentum flow was observed to slow down close to the axis and formed a centrifugal barrier which added new features into the spectrum. Using the Monte Carlo method, we generated the radiated spectra as functions of the accretion rates. We find that the transitions from a hard state to a soft state is determined by the mass accretion rates of the disk and the halo. We separate out the signature of the bulk motion Comptonization and discuss its significance. We study how the n...

  12. Two component silicone modified epoxy foul release coatings: Effect of modulus, surface energy and surface restructuring on pseudobarnacle and macrofouling behavior

    International Nuclear Information System (INIS)

    Two component silicone modified epoxy resin based low surface energy and non-toxic foul release coatings were developed. Silicone modified epoxy resin with 15 and 30% silicone content was used as component A and a polyether diamine (Jeffamine-500) was used as the component B. Free standing films were prepared by casting a mixture of components A and B in stoichiometric proportions. The surface composition, surface topography and wetting properties of the coatings were studied by angle resolved X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle goniometry respectively. The mechanical properties of the cured films were evaluated by tensile measurements as well as dynamic mechanical analysis. Pseudobarnacles made of aluminium studs were attached to the coated panels and adhesion tests were carried out by a pseudobarnacle tester. Coated panels were exposed in Mumbai harbor for fouling studies for a period of 90 days. Surface restructuring studies of the coatings upon immersion in seawater were carried out by measuring the changes in advancing and receding contact angles by contact angle goniometry. The effect of surface energy, modulus and surface restructuring of the coatings on the macrofouling and pseudobarnacle adhesion properties has been discussed in detail.

  13. The two-component adjuvant IC31® boosts type i interferon production of human monocyte-derived dendritic cells via ligation of endosomal TLRs.

    Directory of Open Access Journals (Sweden)

    Attila Szabo

    Full Text Available The aim of this study was to characterize and identify the mode of action of IC31®, a two-component vaccine adjuvant. We found that IC31® was accumulated in human peripheral blood monocytes, MHC class II positive cells and monocyte-derived DCs (moDCs but not in plasmacytoid DCs (pDCs. In the presence of IC31® the differentiation of inflammatory CD1a(+ moDCs and the secretion of chemokines, TNF-α and IL-6 cytokines was inhibited but the production of IFNβ was increased. Sustained addition of IC31® to differentiating moDCs interfered with IκBα phosphorylation, while the level of phospho-IRF3 increased. We also showed that both IC31® and its KLK component exhibited a booster effect on type I IFN responses induced by the specific ligands of TLR3 or TLR7/8, whereas TLR9 ligand induces type I IFN production only in the presence of IC31® or ODN1. Furthermore, long term incubation of moDCs with IC31® caused significantly higher expression of IRF and IFN genes than a single 24 hr treatment. The adjuvant activity of IC31® on the IFN response was shown to be exerted through TLRs residing in the vesicular compartment of moDCs. Based on these results IC31® was identified as a moDC modulatory adjuvant that sets the balance of the NF-κB and IRF3 mediated signaling pathways to the production of IFNβ. Thus IC31® is emerging as a potent adjuvant to increase immune responses against intracellular pathogens and cancer in future vaccination strategies.

  14. Study on Azeotropic Point of Azeotrope with Two Components%对二元溶液体系共沸溶液共沸点的再探究

    Institute of Scientific and Technical Information of China (English)

    曲金华; 杨旭

    2014-01-01

    共沸溶液很早就被人们所发现并取得了大量的实验数据,然而,这种现象的理论研究却很少。本文从理论上推导出二元体系共沸液的共沸点与外压、组成和组分沸点的定量关系式,并据此计算了二元体系共沸溶液常压下的共沸点,结果与文献的实验数据有相当好的一致性。本文还对二元体系共沸溶液的存在范围,共沸点相对单组分沸点高低的定性判定作了分析,从而为共沸溶液的研究和应用提供了理论依据。%Azeotropic solution soon discovered by the people and made the experimental data, a lot of however, theoretical study of this phenomenon is rarely. Quantitative relationship between the theoretically deduced two azeotropic distillation liquid boiling point and external pressure, composition and component boiling point, two component azeotropic solution under atmospheric pressure boiling point was calculated accordingly, the result of experimental data and literature are quite agreement. This paper also points the existence range azeotropic solution of the two group, boiling point to determine relative single component boiling point of qualitative analysis is made, which provides a theoretical basis for the research and application of azeotropic solution.

  15. Flame-Retarding of Cotton/Polyester Blended Yarn Fabrics Using Two-Component Sequential Treatment; Nidankai shori ni yoru men/poriesuteru konboshifu no nannenka

    Energy Technology Data Exchange (ETDEWEB)

    Kubokawa, Hiroo. [Textile Research Institute of Gunma Prefecture, Gunma (Japan)

    1999-01-10

    Cotton/polyester (C/P) blended yarn fabrics were treated with several flame retardants used for poly (ethylene terephthalate)(PET) using pad-dry-cure method. The relationships between the chemical structures of the flame retardants and their partition into PET fibers were investigated. When tetrabromobisphenol A (TBP-A) was tested, the amount of sorption increased with increasing concentration of TBP-A in treating acetone solution, and reached 4.0%o.w.f. (% on the weight of the fibre) at 10 wt%. THis treated fabric was again treated with a flame retardant for cotton, Pyrovatex CP New, which contains dimethyl 2-(N-hydroxymethylcarbamovl)ethylphosphonate as a main component. However, sufficient flame retardancy was not obtained. The second partition of TBP-A to cotton during heating was thought to lower the sorption efficiency of Pyrovatex CP New. Based on this assumption, for the case of the two-component sequential treatment, the Pyrovatex CP New treatment, which generates covalent bonds with hydroxy groups of cellulose, should be carried out prior to the TBP-A treatment. When a C/P blended yarn fabric was treated with Pyrovatex CP New and then with TBP-A, the amount of sorption of Pyrovatex CP New was 9.6%o.w.f. and the amount of sorption of TBP-A was 4.6%o.w.f. The limiting oxygen index of the treated fabric was 27.2%, a sufficient value for flame retardancy. Fromthis result, it was concluded that the practica flame-retardant finishing of c/p blended yarn fabrics could be carried out by using a simple finishing machine. (author)

  16. Theoretical modelling of the adsorption of thallium and element 113 atoms on gold using two-component density functional methods with effective core potentials

    International Nuclear Information System (INIS)

    Highlights: ► In this study we model the adsorption of the superheavy element 113 on gold surfaces. ► The binding energy of element 113 and thallium is calculated for cluster models. ► For many different binding sites, element 113 binds weaker by 90 ± 15 kJ/mol. - Abstract: The adsorption of thallium and element 113 atoms on a gold surface has been modelled by cluster calculations. Quasirelativistic two-component density functional calculations that include spin–orbit coupling self-consistently have been used together with spin-dependent effective core potentials. The validity of this method is demonstrated by comparisons with high-level wave function based calculations on the hetero-dimers AuTl and Au(113). New basis sets had to be generated because standard basis sets optimized for scalar-relativistic calculations are too inflexible to describe the different behaviour of the atomic sub-shells that result from the spin–orbit interaction. The topmost layer of gold atoms within the cluster was allowed to fully relax upon adsorption, and different adsorption sites (on-top, hollow, and bridge) on the (1 0 0) and (1 1 1) surfaces were considered. Spin–orbit coupling reduces the surface binding energies of an element 113 atom much more than it does for Tl, such that the binding energy of element 113 to the gold cluster, as compared to Tl, is reduced by 90 ± 15 kJ/mol in most cases. Together with the experimental result for thallium, this allows an estimate of the adsorption temperature of element 113 in thermochromatography experiments.

  17. The Two-Component Model for Calculating Total Body Fat from Body Density: An Evaluation in Healthy Women before, during and after Pregnancy

    Directory of Open Access Journals (Sweden)

    Elisabet Forsum

    2014-12-01

    Full Text Available A possibility to assess body composition during pregnancy is often important. Estimating body density (DB and use the two-component model (2CM to calculate total body fat (TBF represents an option. However, this approach has been insufficiently evaluated during pregnancy. We evaluated the 2CM, and estimated fat-free mass (FFM density and variability in 17 healthy women before pregnancy, in gestational weeks 14 and 32, and 2 weeks postpartum based on DB (underwater weighing, total body water (deuterium dilution and body weight, assessed on these four occasions. TBF, calculated using the 2CM and published FFM density (TBF2CM, was compared to reference estimates obtained using the three-component model (TBF3CM. TBF2CM minus TBF3CM (mean ± 2SD was −1.63 ± 5.67 (p = 0.031, −1.39 ± 7.75 (p = 0.16, −0.38 ± 4.44 (p = 0.49 and −1.39 ± 5.22 (p = 0.043 % before pregnancy, in gestational weeks 14 and 32 and 2 weeks postpartum, respectively. The effect of pregnancy on the variability of FFM density was larger in gestational week 14 than in gestational week 32. The 2CM, based on DB and published FFM density, assessed body composition as accurately in gestational week 32 as in non-pregnant adults. Corresponding values in gestational week 14 were slightly less accurate than those obtained before pregnancy.

  18. Computer studies of the surface mechanism of preferential sputtering of two-component solids. Ion beam analysis of surface composition in low dose regime

    Science.gov (United States)

    Samoilov, Vladimir N.; Tatur, Andrei E.; Yastrzhembsky, Vladimir I.

    1996-09-01

    We investigated the process of collision cascade propagation through the solid-vacuum boundary for two-component targets: WSi, MoSi and VSi. The surface mechanism of preferential sputtering of atoms of light component based on stronger deflection of light atoms towards surface normal when scattering by heavy neighbouring surface atoms during ejection was studied. Simulations for ejection of 450 000 Si or W atoms from the surface of WSi for cos {ϑ 0}/{E 02} and {1}/{E 02} initial distributions gave {Si}/{W} sputtering ratio equal to 1.29-1.55 (for 1:1 {Si}/{W} concentration ratio at the surface) giving necessary addition to the Andersen-Sigmund formula which underestimated that ratio in comparison with available experimental data. Analysis of integral energy distributions of atoms of the components gave {Si}/{W} ratio maximum equal to 3.18-5.00 for energy interval 0.0-0.4 eV. Maxima of integral energy distributions of sputtered atoms were observed at 1.8 eV for Si and 3.4 eV for W in calculations with equal binding energies for atoms of light and heavy components in good agreement with experiment. The surface mechanism was shown to be the alternative mechanism in formation of observed maxima difference with respect to nonidentity of binding energy values for atoms of components proposed by Szymonski [Phys. Lett. A 82 (1981) 203]. The two-cone structure of ejection vs. initial polar angle for Si atoms sputtered was revealed and explained. Results obtained gave the new approach to solve the inverse problem of reconstruction of surface composition in low dose SNMS and showed that the surface mechanism of preferential sputtering is to be accounted for in analytical calculations of surface composition. Ejection was simulated in the plane containing the neighbouring surface atom.

  19. Synthesis and characterization of two-component waterborne acrylic-polyurethane%水性双组分丙烯酸-聚氨酯的合成与表征

    Institute of Scientific and Technical Information of China (English)

    周新华; 张灵娟; 涂伟萍; 胡剑青

    2005-01-01

    A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water soluble acrylic resin and HDI biuret, and then diluting it to phase inversion with water. The effect of formula of acrylic resin on the performance of 2K-WPU was studied and the cured film of 2K-WPU was characterized by FTIR. It is shown that, ponent polyurethane emulsion with fine particle size can be achieved. When the film dried at room temperature for12 h, curing reaction can complete and the film has high crosslinking density.%使用相转化法,即将水溶性丙烯酸树脂和HDI缩二脲混合,然后加水稀释转相,制备了水性双组分丙烯酸聚氨酯.研究了丙烯酸树脂配方对双组分聚氨酯性能的影响,并用红外光谱(FTIR)对涂膜固化进行了表征.结果表明,以丙二醇甲醚醋酸酯为溶剂,在羟值为120 mgKOH·g-1、酸值为30 mgKOH·g-1的水溶性丙烯酸树脂中,添加10%的甲基丙烯酸异冰片酯,获得的双组分聚氨酯乳液粒径小.室温干燥12 h,固化反应完成,涂膜交联密度高.

  20. Structure-guided mutagenesis of active site residues in the dengue virus two-component protease NS2B-NS3

    Directory of Open Access Journals (Sweden)

    Salaemae Wanisa

    2010-08-01

    Full Text Available Abstract Background The dengue virus two-component protease NS2B/NS3 mediates processing of the viral polyprotein precursor and is therefore an important determinant of virus replication. The enzyme is now intensively studied with a view to the structure-based development of antiviral inhibitors. Although 3-dimensional structures have now been elucidated for a number of flaviviral proteases, enzyme-substrate interactions are characterized only to a limited extend. The high selectivity of the dengue virus protease for the polyprotein precursor offers the distinct advantage of designing inhibitors with exquisite specificity for the viral enzyme. To identify important determinants of substrate binding and catalysis in the active site of the dengue virus NS3 protease, nine residues, L115, D129, G133, T134, Y150, G151, N152, S163 and I165, located within the S1 and S2 pockets of the enzyme were targeted by alanine substitution mutagenesis and effects on enzyme activity were fluorometrically assayed. Methods Alanine substitutions were introduced by site-directed mutagenesis at residues L115, D129, G133, T134, Y150, G151, N152, S163 and I165 and recombinant proteins were purified from overexpressing E. coli. Effects of these substitutions on enzymatic activity of the NS3 protease were assayed by fluorescence release from the synthetic model substrate GRR-amc and kinetic parameters Km, kcat and kcat/Km were determined. Results Kinetic data for mutant derivatives in the active site of the dengue virus NS3 protease were essentially in agreement with a functional role of the selected residues for substrate binding and/or catalysis. Only the L115A mutant displayed activity comparable to the wild-type enzyme, whereas mutation of residues Y150 and G151 to alanine completely abrogated enzyme activity. A G133A mutant had an approximately 10-fold reduced catalytic efficiency thus suggesting a critical role for this residue seemingly as part of the oxyanion

  1. Modeling the monthly mean soil-water balance with a statistical-dynamical ecohydrology model as coupled to a two-component canopy model

    Directory of Open Access Journals (Sweden)

    J. P. Kochendorfer

    2010-10-01

    Full Text Available The statistical-dynamical annual water balance model of Eagleson (1978 is a pioneering work in the analysis of climate, soil and vegetation interactions. This paper describes several enhancements and modifications to the model that improve its physical realism at the expense of its mathematical elegance and analytical tractability. In particular, the analytical solutions for the root zone fluxes are re-derived using separate potential rates of transpiration and bare-soil evaporation. Those potential rates, along with the rate of evaporation from canopy interception, are calculated using the two-component Shuttleworth-Wallace (1985 canopy model. In addition, the soil column is divided into two layers, with the upper layer representing the dynamic root zone. The resulting ability to account for changes in root-zone water storage allows for implementation at the monthly timescale. This new version of the Eagleson model is coined the Statistical-Dynamical Ecohydrology Model (SDEM. The ability of the SDEM to capture the seasonal dynamics of the local-scale soil-water balance is demonstrated for two grassland sites in the US Great Plains. Sensitivity of the results to variations in peak green leaf area index (LAI suggests that the mean peak green LAI is determined by some minimum in root zone soil moisture during the growing season. That minimum appears to be close to the soil matric potential at which the dominant grass species begins to experience water stress and well above the wilting point, thereby suggesting an ecological optimality hypothesis in which the need to avoid water-stress-induced leaf abscission is balanced by the maximization of carbon assimilation (and associated transpiration. Finally, analysis of the sensitivity of model-determined peak green LAI to soil texture shows that the coupled model is able to reproduce the so-called "inverse texture effect", which consists of the observation that natural vegetation in dry climates tends

  2. Modeling the monthly mean soil-water balance with a statistical-dynamical ecohydrology model as coupled to a two-component canopy model

    Directory of Open Access Journals (Sweden)

    J. P. Kochendorfer

    2008-03-01

    Full Text Available The statistical-dynamical annual water balance model of Eagleson (1978 is a pioneering work in the analysis of climate, soil and vegetation interactions. This paper describes several enhancements and modifications to the model that improve its physical realism at the expense of its mathematical elegance and analytical tractability. In particular, the analytical solutions for the root zone fluxes are re-derived using separate potential rates of transpiration and bare-soil evaporation. Those potential rates, along with the rate of evaporation from canopy interception, are calculated using the two-component Shuttleworth-Wallace (1985 canopy model. In addition, the soil column is divided into two layers, with the upper layer representing the dynamic root zone. The resulting ability to account for changes in root-zone water storage allows for implementation at the monthly timescale. This new version of the Eagleson model is coined the Statistical-Dynamical Ecohydrology Model (SDEM. The ability of the SDEM to capture the seasonal dynamics of the local-scale soil-water balance is demonstrated for two grassland sites in the US Great Plains. Sensitivity of the results to variations in peak green Leaf Area Index (LAI suggests that the mean peak green LAI is determined by some minimum in root zone soil moisture during the growing season. That minimum appears to be close to the soil matric potential at which the dominant grass species begins to experience water stress and well above the wilting point, thereby suggesting an ecological optimality hypothesis in which the need to avoid water-stress-induced leaf abscission is balanced by the maximization of carbon assimilation (and associated transpiration. Finally, analysis of the sensitivity of model-determined peak green LAI to soil texture shows that the coupled model is able to reproduce the so-called "inverse texture effect", which consists of the observation that natural vegetation in dry climates tends

  3. Path-Integral Monte Carlo Determination of the Fourth-Order Virial Coefficient for a Unitary Two-Component Fermi Gas with Zero-Range Interactions.

    Science.gov (United States)

    Yan, Yangqian; Blume, D

    2016-06-10

    The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b_{4} of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b_{4}, our b_{4} agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions. PMID:27341213

  4. Path-Integral Monte Carlo Determination of the Fourth-Order Virial Coefficient for a Unitary Two-Component Fermi Gas with Zero-Range Interactions

    Science.gov (United States)

    Yan, Yangqian; Blume, D.

    2016-06-01

    The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b4 of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4 , our b4 agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions.

  5. Nonautonomous vector matter waves in two-component Bose-Einstein condensates with combined time-dependent harmonic-lattice potential

    International Nuclear Information System (INIS)

    We construct exact self-similar soliton solutions of three-dimensional coupled Gross–Pitaevskii equations for two-species Bose–Einstein condensates (BECs) in a combined time-dependent harmonic-lattice potential. Based on these solutions, we investigate the control and manipulation of solitary waves for three kinds of BECs with changing diffraction and nonlinearity coefficients; the solutions include Ma breathers and Peregrine and Akhmediev soliton solutions. Our results indicate that matter waves readily propagate in this system. It is shown that diffraction and lattice potential factors play important roles in the beam evolution characteristics, such as the peak, the phase offset, the linear phase, and the chirp. (paper)

  6. Ripples and the formation of anisotropic lipid domains: Imaging two-component double bilayers by atomic force microscopy_copy_03

    DEFF Research Database (Denmark)

    Leidy, C.; Kaasgaard, Thomas; Crowe, J.H.; Mouritsen, O.G.; Jørgensen, K.

    2002-01-01

    Direct visualization of the fluid-phase/ordered-phase domain structure in mica-supported bilayers composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-distearoyl-sn-glycero-3-phosphocholine mixtures is performed with atomic force microscopy. The system studied is a double bilayer supported...... on a mica surface in which the top bilayer (which is not in direct contact with the mica) is visualized as a function of temperature. Because the top bilayer is not as restricted by the interactions with the surface as single supported bilayers, its behavior is more similar to a free-standing bilayer...... by atomic force microscopy, we investigated the origin of these anisotropic lipid domain patterns, and found that ripple phase formation is directly responsible for the anisotropic nature of these domains. The nucleation and growth of fluid-phase domains are found to be directed by the presence of...

  7. Two component-three dimensional catalysis

    Science.gov (United States)

    Schwartz, Michael; White, James H.; Sammells, Anthony F.

    2002-01-01

    This invention relates to catalytic reactor membranes having a gas-impermeable membrane for transport of oxygen anions. The membrane has an oxidation surface and a reduction surface. The membrane is coated on its oxidation surface with an adherent catalyst layer and is optionally coated on its reduction surface with a catalyst that promotes reduction of an oxygen-containing species (e.g., O.sub.2, NO.sub.2, SO.sub.2, etc.) to generate oxygen anions on the membrane. The reactor has an oxidation zone and a reduction zone separated by the membrane. A component of an oxygen containing gas in the reduction zone is reduced at the membrane and a reduced species in a reactant gas in the oxidation zone of the reactor is oxidized. The reactor optionally contains a three-dimensional catalyst in the oxidation zone. The adherent catalyst layer and the three-dimensional catalyst are selected to promote a desired oxidation reaction, particularly a partial oxidation of a hydrocarbon.

  8. Decelerating relativistc two-component jets

    OpenAIRE

    Meliani, Z.; Keppens, R.

    2009-01-01

    Transverse stratification is a common intrinsic feature of astrophysical jets. There is growing evidence that jets in radio galaxies consist of a fast low-density outflow at the jet axis, surrounded by a slower, denser, extended jet. The inner and outer jet components then have a different origin and launching mechanism, making their effective inertia, magnetization, associated energy flux, and angular momentum content different as well. Their interface will develop differential rotation, whe...

  9. Measures on two-component configuration spaces

    CERN Document Server

    Finkelshtein, D L

    2007-01-01

    We study measures on the configuration spaces of two type particles. Gibbs measures on the such spaces are described. Main properties of corresponding relative energies densities and correlation functions are considered. In particular, we show that a support set for the such Gibbs measure is the set of pairs of non-intersected configurations.

  10. Measures on two-component configuration spaces

    Directory of Open Access Journals (Sweden)

    D.L. Finkelshtein

    2009-01-01

    Full Text Available We study the measures on the configuration spaces of particles of two types. Gibbs measures on such spaces are described. Main properties of corresponding relative energy densities and correlation functions are considered. In particular, we show that a support set for such Gibbs measure is the set of pairs of non-intersected configurations.

  11. Crosscap Numbers of Two-component Links

    OpenAIRE

    Zhang, Gengyu

    2006-01-01

    We define the crosscap number of a 2-component link as the minimum of the first Betti numbers of connected, non-orientable surfaces bounding the link. We discuss some properties of the crosscap numbers of 2-component links.

  12. Mass loss from inhomogeneous hot star winds III. An effective-opacity formalism for line radiative transfer in accelerating, clumped two-component media, and first results on theory and diagnostics

    OpenAIRE

    Sundqvist, J. O.; Puls, J.; Owocki, S. P.

    2014-01-01

    [Abridged] We develop and benchmark a fast and easy-to-use effective-opacity formalism for line and continuum radiative transfer in an accelerating two-component clumpy medium. The formalism bridges the limits of optically thin and thick clumps, and is here used to i) design a simple vorosity-modified Sobolev with exact integration (vmSEI) method for analyzing UV wind resonance lines in hot, massive stars, and ii) derive simple correction factors to the line force driving the outflows of such...

  13. Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential

    International Nuclear Information System (INIS)

    We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues

  14. Two-component multi-configurational second-order perturbation theory with Kramers restricted complete active space self-consistent field reference function and spin-orbit relativistic effective core potential

    Science.gov (United States)

    Kim, Inkoo; Lee, Yoon Sup

    2014-10-01

    We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues.

  15. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    Science.gov (United States)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  16. Preparation and Characterization of Two-component Waterborne Polyurethane Comprised of Water-soluble Acrylic Resin and HDI Biuret%水性双组份丙烯酸聚氨酯的合成与表征

    Institute of Scientific and Technical Information of China (English)

    周新华; 涂伟萍; 胡剑青

    2006-01-01

    A two-component waterborne polyurethane (2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU particles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI isocyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction between HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on pefformance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.

  17. Characterization of the two-component, FAD-dependent monooxygenase SgcC that requires carrier protein-tethered substrates for the biosynthesis of the enediyne antitumor antibiotic C-1027.

    Science.gov (United States)

    Lin, Shuangjun; Van Lanen, Steven G; Shen, Ben

    2008-05-21

    C-1027 is a potent antitumor antibiotic composed of an apoprotein (CagA) and a reactive enediyne chromophore. The chromophore has four distinct chemical moieties, including an ( S)-3-chloro-5-hydroxy-beta-tyrosine moiety, the biosynthesis of which from l-alpha-tyrosine requires five proteins: SgcC, SgcC1, SgcC2, SgcC3, and SgcC4; a sixth protein, SgcC5, catalyzes the incorporation of this beta-amino acid moiety into C-1027. Biochemical characterization of SgcC has now revealed that (i) SgcC is a two-component, flavin adenine dinucleotide (FAD)-dependent monooxygenase, (ii) SgcC is only active with SgcC2 (peptidyl carrier protein)-tethered substrates, (iii) SgcC-catalyzed hydroxylation requires O 2 and FADH 2, the latter supplied by the C-1027 pathway-specific flavin reductase SgcE6 or Escherichia coli flavin reductase Fre, and (iv) SgcC efficiently catalyzes regioselective hydroxylation of 3-substituted beta-tyrosyl-S-SgcC2 analogues, including the chloro-, bromo-, iodo-, fluoro-, and methyl-substituted analogues, but does not accept 3-hydroxy-beta-tyrosyl-S-SgcC2 as a substrate. Together with the in vitro data for SgcC4, SgcC1, and SgcC3, the results establish that SgcC catalyzes the hydroxylation of ( S)-3-chloro-beta-tyrosyl-S-SgcC2 as the final step in the biosynthesis of the ( S)-3-chloro-5-hydroxy-beta-tyrosine moiety prior to incorporation into C-1027. SgcC now represents the first biochemically characterized two-component, FAD-dependent monooxygenase that acts on a carrier-protein-tethered aromatic substrate. PMID:18426211

  18. 非焦油型双组分聚氨酯防水涂料的研制%Preparation of Non-tar-type Two-component Polyurethane Waterproof Coating

    Institute of Scientific and Technical Information of China (English)

    马俊

    2012-01-01

    通过一定比例合成含有NCO的聚氨酯预聚体为A组分,将粉料、聚醚、MOCA、助剂等制成B组分,将A、B组分按质量比1:2混合成膜制得非焦油型双组分聚氨酯涂料。探讨了NCO含量、MOCA、催化助剂、消泡荆对双组分聚氨酯涂料的影响,结果表明:NCO含量在4.O%。4.6%、MOCA含量在2.5%~4.0%、催化剂在0.08%~0.12%、消泡剂在013%~0.7%,可以制得性能优异的双组分聚氨酯涂料。%Polyurethane prepolymer with NCO groups was synthesized by proportional mixing as A component, B component was made of powder, polyether, MOCA and additives, and non-tar polyurethane coating was prepared by A, B components according to the mass ratio of 1 : 2. Influencing factors of two components polyurethane coating that caused by content of NCO, MOCA, catalytic agent, defoaming agent were discussed. The results showed that: high performance two-component polyurethane coating can be prepared when the content of NCO is 4.0%- 4.6%, MOCA content is 2.5% -4.0%, catalyst is 0.08% 0.12% and defoaming agent is 0.3%- 0.7%.

  19. 一种低成本室温固化双组分环氧密封胶的研制%Preparation of a low-cost room temperature curable two-component epoxy sealant

    Institute of Scientific and Technical Information of China (English)

    李吉明; 薛纪东; 钟汉荣

    2013-01-01

    A low-cost room temperature curable two-component epoxy sealant was prepared with liquid bisphenol A type epoxy resin and modified amines.Its curing mechanism was discussed in this paper.The effect of temperature and two component weight ratio on the working life and the effect of the amounts of silica powder and dioctyl phthalate on the bonding strength were also studied.The experimental results showed that the change of temperature could affect the working life obviously.The working life of product got shorter while its reaction rate speeded up due to the elevation of temperature.When the silica powder amount was 30~75 phrs,the wettability of sealant got poor,the defects in cured sealant layer increased,amd the tensile shear strength decreased with increasing the silica powder amount.The adding of dioctyl phthalate decreased the cross-linking desity of cured sealant and the bonding strength of modified resin.%采用低分子质量双酚A型环氧树脂及改性胺类固化剂研制了一种低成本室温固化双组分环氧胶粘剂。探讨了其固化机理,考查了温度、配比对适用期的影响,以及硅微粉、邻苯二甲酸二辛酯的用量对胶接强度的影响。结果表明,温度变化对该产品的适用期影响较大。温度升高,适用期变短。硅微粉加入量在30~75份时,胶的湿润性变差,固化后的胶层缺陷增多,拉伸剪切强度随硅微粉用量的增大而下降。邻苯二甲酸二辛酯的加入降低固化后的交联密度,使环氧胶的胶接强度下降。

  20. 双组分聚氨酯涂料用改性醇酸树脂的研究%Research of Modified Alkyd Resin for Two-Component Polyurethane Coatings

    Institute of Scientific and Technical Information of China (English)

    刘清福; 徐朝华; 夏德慧

    2012-01-01

    The two-component polyurethane coatings were compounded with modified short oil alkyd resin as A component and isocyanate prepolymers as B component. The effect of A component on two-component polyurethane coatings were investigated. The results showed that coconut oil modification short oil alkyd resin could be used as gloss paint, yellowing resistance finish for its pure white color, yellowing resistance properties and good fullness. Castor oil modification short oil alkyd resin could be used as ordinary finish painted resin for its deep color, good fullness, lower drying rate and excellent flexility. Soybean oil modification short oil alkyd resin could be used as primer and matte paint for its fast drying rate. Synthetic fatty acid modification short oil alkyd resin could be used as high-grade finish painted resin for the pure while color, good level ability, slow-speeded drying, nice fullness and high hardness.%采用不同改性的短油度醇酸树脂作甲组分,异氰酸酯预聚物作乙组分,配制双组分聚氨酯涂料,探讨甲组分对双组分聚氨酯涂料性能的影响.结果表明,椰子油改性短油度醇酸树脂,颜色水白、耐黄变性能和丰满度好,可以作为高档的亮光清面漆、耐黄变的面漆用树脂;蓖麻油改性短油度醇酸树脂,颜色较深、丰满度较好、干燥速度慢及柔韧性好,可以作为普通的亮光面漆用树脂;豆油改性短油度醇酸树脂,干燥速度较快,应用于底漆和哑光面漆;合成脂肪酸改性短油度醇酸树脂,颜色水白、流平好、干燥速度慢、丰满度高及硬度高,可以作为高档的亮光面漆用树脂.

  1. Simultaneous Determination of two Components in Compound Tinidazole Gargles by Multiply Factor Method%用乘子法同时测定复方替硝唑含漱液中二组分的含量

    Institute of Scientific and Technical Information of China (English)

    魏得良; 郭皖北; 周明达; 王曼娟; 刘建华

    2006-01-01

    In this paper, the basic principle and computing of multiply factor method applied to multicomponent analysis were discussed. The method was applied to simultaneous determination of two components in compound tinidazole gargles. The average recovery of Chlorhexidine and tinidazole in simulation samples was 99.75%、100.17% and relative standard deviations for them were 0.73%、0.42% respectively (n=10). The results of determination for three batches of actual samples were agreed with those by standard method. This method promises well to be adopted as an official assay method for compound tinidazole gargles.%用乘子法处理多波长吸光度数据,同时测定复方替硝唑含漱液中二组分的含量.简要介绍了乘子法的原理和计算步骤,模拟样品中醋酸氯已定、替硝唑的平均回收率分别为99.75%,100.17%,标准偏差分别为0.73%,0.42%(n=10),对三个批号实际样品的测定结果与标准方法吻合.与标准方法相比,该方法具有简便、快速、易于实现自动分析的优点.

  2. Interpretation of the two-components observed in high resolution X-ray diffraction ω scan peaks for mosaic ZnO thin films grown on c-sapphire substrates using pulsed laser deposition

    International Nuclear Information System (INIS)

    X-ray scattering methods were applied to the study of thin mosaic ZnO layers deposited on c-Al2O3 substrates using Pulsed Laser Deposition. High Resolution (HR) studies revealed two components in the ω scans (transverse scans) which were not resolved in conventional 'open-detector' ω rocking curves: a narrow, resolution-limited, peak, characteristic of long-range correlation, and a broad peak, attributed to defect-related diffuse-scattering inducing a limited transverse structural correlation length. Thus, for such mosaic films, the conventional ω rocking curve Full Width at Half Maximum linewidth was found to be ill-adapted as an overall figure-of-merit for the structural quality, in that the different contributions were not meaningfully represented. A 'Williamson-Hall like' integral breadth (IB) metric for the HR (00.l) transverse-scans was thus developed as a reliable, fast, accurate and robust alternative to the rocking curve linewidth for routine non-destructive testing of such mosaic thin films. For a typical ZnO/c-Al2O3 film, the IB method gave a limited structural correlation length of 110 nm ± 9 nm. The results are coherent with a thin film containing misfit dislocations at the film-substrate interface.

  3. 液体古马隆改性双组分聚氨酯涂料的制备和性能%Preparation and properties of liquid coumarone modified two-component polyurethane coating

    Institute of Scientific and Technical Information of China (English)

    冯涛; 韩胜利; 杨足明; 周柳

    2012-01-01

    The liquid coumarone modified two-component polyurethane coating was prepared,among which the component A is the prepolymcr containing NCO groups and the component B is the curing agent containing mixed diamine and liquid coumarone.The effects of ratio of triol and diol,NCO group content,liquid coumarone amount etc.,on the film properties were discussed and the optimal formulation was obtained.The tensile strength is 2.5 MPa.the elongation at break is 750% and the solid content is over 99%,that can achieve the requirements,in standard GB/T 19250-2003.%制备了液体古马隆改性的双组分聚氨酯涂料,其中A组分为含-NCO的预聚物,B组分为含混合二元胺和液体古马隆的固化剂.分别讨论了三元醇和二元醇的比例、-NCO含量、液体古马隆添加量等对涂膜性能的影响,得到最优化的配方.胶膜强度为2.5 MPa,断裂伸长率为750%.涂料固含量大于99%,可以达到《GB/T 19250-2003聚氨酯防水涂料》规定的指标要求.

  4. Mass loss from inhomogeneous hot star winds III. An effective-opacity formalism for line radiative transfer in accelerating, clumped two-component media, and first results on theory and diagnostics

    CERN Document Server

    Sundqvist, J O; Owocki, S P

    2014-01-01

    [Abridged] We develop and benchmark a fast and easy-to-use effective-opacity formalism for line and continuum radiative transfer in an accelerating two-component clumpy medium. The formalism bridges the limits of optically thin and thick clumps, and is here used to i) design a simple vorosity-modified Sobolev with exact integration (vmSEI) method for analyzing UV wind resonance lines in hot, massive stars, and ii) derive simple correction factors to the line force driving the outflows of such stars. We show that (for a given ionization factor) UV resonance doublets may be used to analytically predict the upward corrections in empirically inferred mass-loss rates associated with porosity in velocity space (a.k.a. velocity-porosity, or vorosity), but that severe solution degeneracies exist. For an inter-clump density set to 1 % of the mean density, we for O and B supergiants derive upward empirical mass-loss corrections of typically factors of either ~5 or ~50, depending on which of the two applicable solutions...

  5. Final report of research supported by DOE Grant No. DE-FG02-96ER14635: Photochemical studies of two component systems within the restricted spaces of zeolites.; FINAL

    International Nuclear Information System (INIS)

    Most chemistry in nature occurs within a closed and confined space. In contrast to this time-evolved[m?] organic chemists have focused their interests in developing reaction methods in solution. The price for this is paid in terms of non-selectivity in product formation, expensive reagents, and enormous wastes. Eventually 'man-developed' solution methods to make molecules have to be replaced by more selective, more environmentally friendly, and less expensive strategies. One approach in this direction would be to use controlled environments. The project focused towards developing energy efficient methods to prepare energy rich molecules that were useful to the public. In this context synthetic zeolites, the counterpart of naturally occurring minerals, were explored as the reaction media

  6. Synthetic lac Operator Substitutions for Studying the Nitrate- and Nitrite-Responsive NarX-NarL and NarQ-NarP Two-Component Regulatory Systems of Escherichia coli K-12

    OpenAIRE

    Stewart, Valley; Bledsoe, Peggy J.

    2003-01-01

    The NarX and NarQ sensor-histidine kinases control phosphorylation of the NarL and NarP response regulators in response to the respiratory oxidants nitrate and nitrite. Target operon transcription is activated by the Fnr protein in response to anaerobiosis, and it is further activated and/or repressed by the phospho-NarL and phospho-NarP proteins, which bind to heptamer DNA sequences. The location and arrangement of heptamers vary widely among different target operon control regions. We have ...

  7. Final report of research supported by DOE Grant No. DE-FG02-96ER14635: Photochemical studies of two component systems within the restricted spaces of zeolites.

    Energy Technology Data Exchange (ETDEWEB)

    Ramamurthy, V.

    2002-05-05

    Most chemistry in nature occurs within a closed and confined space. In contrast to this time-evolved [m?] organic chemists have focused their interests in developing reaction methods in solution. The price for this is paid in terms of non-selectivity in product formation, expensive reagents, and enormous wastes. Eventually 'man-developed' solution methods to make molecules have to be replaced by more selective, more environmentally friendly, and less expensive strategies. One approach in this direction would be to use controlled environments. The project focused towards developing energy efficient methods to prepare energy rich molecules that were useful to the public. In this context synthetic zeolites, the counterpart of naturally occurring minerals, were explored as the reaction media.

  8. CesRK, a two-component signal transduction system in Listeria monocytogenes, responds to the presence of cell wall-acting antibiotics and affects beta-lactam resistance

    DEFF Research Database (Denmark)

    Kallipolitis, Birgitte H; Ingmer, Hanne; Gahan, Cormac G;

    2003-01-01

    Listeria monocytogenes is a food-borne pathogen that can cause a variety of illnesses ranging from gastroenteritis to life-threatening septicemia. The beta-lactam antibiotic ampicillin remains the drug of choice for the treatment of listeriosis. We have previously identified a response regulator of...

  9. Role of the Single Regulator MrsR1 and the Two-Component System MrsR2/K2 in the Regulation of Mersacidin Production and Immunity

    OpenAIRE

    Guder, André; Schmitter, Tim; Wiedemann, Imke; Sahl, Hans-Georg; Bierbaum, Gabriele

    2002-01-01

    The lantibiotic mersacidin is an antimicrobial peptide of 20 amino acids which inhibits bacterial cell wall biosynthesis by binding to the precursor molecule lipid II and which is produced by Bacillus sp. strain HIL Y-85,54728. The structural gene of mersacidin as well as accessory genes is organized in a biosynthetic gene cluster which is located on the chromosome and contains three open reading frames with similarities to regulatory proteins: mrsR2 and mrsK2 encode two proteins with homolog...

  10. Study on preparation and properties of two-components PU adhesive for PP or PE%PP或PE用双组分PU胶粘剂的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    林星; 胡佳; 蔡海元; 崔爱玲; 林中祥

    2012-01-01

    以聚酯多元醇、混合异氰酸酯(MDI/TDI)、扩链剂(1,2-丙二醇)、异氰酸酯固化剂(TMP-TDI)和溶剂(乙酸乙酯)等为主要原料,制备了PP(聚丙烯)、PE(聚乙烯)粘接用双组分PU(聚氨酯)胶粘剂.研究结果表明:当m(结晶性聚酯多元醇)∶m(非结晶性聚酯多元醇)=80∶20~60∶40、R=n(-NCO)/n(-OH)=0.95~0.97、m(MDI)∶m(TDI)=90∶10~60∶40和w(功能性聚酯多元醇XCP-2325)=2%时,PU预聚体的相对分子质量为(9~11)×104,其常温固化12h后的邵A硬度(76)有利于PU预聚体的破碎;当PU预聚体/乙酸乙酯溶液的固含量为12%时,双组分PU胶粘剂的操作性能(黏度为22 mPa·s)、180°剥离强度(初始2.3 N/25 mm、最终41.0 N/25 mm)俱佳.%With polyester polyol, hybrid isocyanate (MDI/TDI), chain extender (1 , 2-propylene glycol), isocyanate curing agent (TMP-TDI ) and solvent (ethyl acetate) as main raw materials , a two - components PU (polyurethane) adhesive for bonding polypropylene (PP) and polyethylene (PE) was prepared. The research results showed that the molecular weight of PU prepolymer was(9-11 )×104,its Shao A hardness(76) after room temperature curing 12 h was favorable for fragmentation of PU prepolymers when mass fractions of m (crystalline polyester polyol):m(noncrystalline polyester polyol) and m(MDI)-m(TDI) were 80:20-6040 and 90:10-6040 respectively,/? Value or molar ratio of n(-NCO)/n(-OH) was 0.95-0.97,and mass fraction of functional polyester polyol(XCP-2325) was 2%. The two-components PU adhesive had both good operation properties(viscosity at 22 mPa·s) and good 180° peeling strength (initial peeling strength at 2.3 N/25 mm,and final peeling strength at 41.0 N/25 mm) when solid content of PU prepolymers/ethyl acetate solution was 12%.

  11. Isolation and characterization of selective and potent human Fab inhibitors directed to the active-site region of the two-component NS2B-NS3 proteinase of West Nile virus.

    Science.gov (United States)

    Shiryaev, Sergey A; Radichev, Ilian A; Ratnikov, Boris I; Aleshin, Alexander E; Gawlik, Katarzyna; Stec, Boguslaw; Frisch, Christian; Knappik, Achim; Strongin, Alex Y

    2010-05-01

    There is a need to develop inhibitors of mosquito-borne flaviviruses, including WNV (West Nile virus). In the present paper, we describe a novel and efficient recombinant-antibody technology that led us to the isolation of inhibitory high-affinity human antibodies to the active-site region of a viral proteinase. As a proof-of-principal, we have successfully used this technology and the synthetic naive human combinatorial antibody library HuCAL GOLD(R) to isolate selective and potent function-blocking active-site-targeting antibodies to the two-component WNV NS (non-structural protein) 2B-NS3 serine proteinase, the only proteinase encoded by the flaviviral genome. First, we used the wild-type enzyme in antibody screens. Next, the positive antibody clones were counter-screened using an NS2B-NS3 mutant with a single mutation of the catalytically essential active-site histidine residue. The specificity of the antibodies to the active site was confirmed by substrate-cleavage reactions and also by using proteinase mutants with additional single amino-acid substitutions in the active-site region. The selected WNV antibodies did not recognize the structurally similar viral proteinases from Dengue virus type 2 and hepatitis C virus, and human serine proteinases. Because of their high selectivity and affinity, the identified human antibodies are attractive reagents for both further mutagenesis and structure-based optimization and, in addition, for studies of NS2B-NS3 activity. Conceptually, it is likely that the generic technology reported in the present paper will be useful for the generation of active-site-specific antibody probes for multiple enzymes. PMID:20156198

  12. Simulation of Mixing Eveness of Two - component Polyurethane Borehole Sealing Material by CFD Technique%聚氨酯封孔材料双液混合均匀度CFD模拟

    Institute of Scientific and Technical Information of China (English)

    成艳英; 林柏泉; 郝志勇; 高亚斌; 李飞; 代华明; 于俊洋

    2012-01-01

    Polyurethane is one of the most widely used material in borehole sealing. The two - component polyurethane must be mixed first in the static mixer before pumping into the drill hole. There. is no doubt that the mixing quality of polyurethane is very important to the sealing quality of various drillings. A mixing effect evaluation of uneven degree and sample variance through the mathematical meth- ods was established. Based on the previous studies, this paper designed a kind of special static mixer for mixing polyurethane, and car- ried on the optimization of the static mixer's structure by investigating the mixing effect of polyurethane through Fluent numerical simula- tion software.%聚氨酯材料是目前煤矿钻孔密封应用最广泛的材料之一。双液聚氨酯在用封孔泵注入钻孔前,先要在静态混合器中混合,其混合效果对于聚氨酯的封孔质量来说非常重要。利用数学方法建立了基于混合不均匀度和样本方差的混合效果评价指标,在前人研究的基础上,设计了一种适合聚氨酯封孔材料混合的静态混合器。同时运用Fluent数值模拟软件,考察聚氨酯在混合器内的混合效果,进而对静态混合器的结构参数进行优化。

  13. NADPH-dependent reductive biotransformation with Escherichia coli and its pfkA deletion mutant: influence on global gene expression and role of oxygen supply.

    Science.gov (United States)

    Siedler, Solvej; Bringer, Stephanie; Polen, Tino; Bott, Michael

    2014-10-01

    An Escherichia coli ΔpfkA mutant lacking the major phosphofructokinase possesses a partially cyclized pentose phosphate pathway leading to an increased NADPH per glucose ratio. This effect decreases the amount of glucose required for NADPH regeneration in reductive biotransformations, such as the conversion of methyl acetoacetate (MAA) to (R)-methyl 3-hydroxybutyrate (MHB) by an alcohol dehydrogenase from Lactobacillus brevis. Here, global transcriptional analyses were performed to study regulatory responses during reductive biotransformation. DNA microarray analysis revealed amongst other things increased expression of soxS, supporting previous results indicating that a high NADPH demand contributes to the activation of SoxR, the transcriptional activator of soxS. Furthermore, several target genes of the ArcAB two-component system showed a lower mRNA level in the reference strain than in the ΔpfkA mutant, pointing to an increased QH2 /Q ratio in the reference strain. This prompted us to analyze yields and productivities of MAA reduction to MHB under different oxygen regimes in a bioreactor. Under anaerobic conditions, the specific MHB production rates of both strains were comparable (7.4 ± 0.2 mmolMHB  h(-1)  gcdw (-1) ) and lower than under conditions of 15% dissolved oxygen, where those of the reference strain (12.8 mmol h(-1)  gcdw (-1) ) and of the ΔpfkA mutant (11.0 mmol h(-1)  gcdw (-1) ) were 73% and 49% higher. While the oxygen transfer rate (OTR) of the reference strain increased after the addition of MAA, presumably due to the oxidation of the acetate accumulated before MAA addition, the OTR of the ΔpfkA strain strongly decreased, indicating a very low respiration rate despite sufficient oxygen supply. The latter effect can likely be attributed to a restricted conversion of NADPH into NADH via the soluble transhydrogenase SthA, as the enzyme is outcompeted in the presence of MAA by the recombinant NADPH-dependent alcohol

  14. 简谐势+四次势阱中两组分自旋轨道耦合旋转玻色爱因斯坦凝聚体%Two-component Bose-Einstein Condensates in Harmonic Plus Quartic Potential with Spin-orbit-coupled and Rotation

    Institute of Scientific and Technical Information of China (English)

    陈光平

    2015-01-01

    采用中心差分和虚时演化数值实验方法研究了简谐势+四次势阱中自旋轨道耦合作用下的两分量旋转玻色爱因斯坦凝聚体。发现自旋轨道作用强度和原子种间相互作用对系统基态结构有着重要的影响,原子种间相互作用强度的增加可使系统从相混合变化成相分离;而自旋轨道耦合作用强度的增加,可使系统从相分离的状态变化成相混合,并产生涡旋、形成分块边界。%The two-component Bose-Einstein condensates in harmonic plus quartic potential with spin-orbit-coupled and rotation have been studied by the finite difference and image-time propagating numerical method. It is found that the inter-component interaction and the strength of the spin-orbit-coupled play an important role in the system’ s ground states. The system can transform from the phase co-exist to the phase separation with the increase of the inter-component interaction;with the increase of the strength of spin-orbit-coupled, the system can trans⁃form from phase separation to phase co-exist, at the same time, there are vortex and domain in the ground state of the system.

  15. Development of Waterborne Two-component Polyurethane Drawable and Anti-graffiti Wall Coatings%水性双组分聚氨酯可绘画和抗涂鸦涂料的研制

    Institute of Scientific and Technical Information of China (English)

    唐英; 蔡伟; 危春阳

    2015-01-01

    Waterborne drawable interior and exterior wall coatings were developed with excellent graffiti removal ability, scrub-resistance and application properties by using waterborne two-component polyurethane and curing agent as film-forming substances. The effect of the binder types and the mixing ratios of waterborne polyurethane and curing agent were discussed, including the dosage of water on the graffiti removal ability of the coatings. The marks of this drawable coatings by a water mark pen, water color pen, dustless chalk, shoe polish, ink, tomato juice, coffee and black tea can be easily cleaned. The compositions in this paint meet the requirements of all the related environment standards. In particular, VOC content is only 11 g/L, which is much lower than the VOC limit 20 g/L in T31/01002-C001—2014 for waterborne interior coatings. This product was environmentally friendly and suitable for kids' rooms, kindergarten, schools, hospitals, hotels and public places.%使用水性双组分聚氨酯乳液及固化剂技术开发出具有优异的耐涂鸦性能,和高度环境友好的水性内外墙可擦洗的绘画涂料.研究了水性聚氨酯乳液/固化剂种类、比例、稀释剂水添加量等因素对绘画涂料涂层上涂鸦物质清除性能等的影响,并对比测试了涂料的综合性能,制备出了兼具优异涂鸦清除性能、环保性能、耐擦洗性能、施工性能等综合性能优异的水性内墙绘画涂料.经试验测试,涂层表面能够轻松清除水性白板笔、水彩笔、无尘粉笔等涂鸦物质以及鞋油、墨水、番茄酱、咖啡、红茶等多种生活污渍,涂料的组分达到所有相关的环保标准要求,尤其是挥发性有机化合物(VOC)含量仅为11 g/L,远低于T31/01002-C001—2014《儿童水性内墙涂料》标准中VOC的限制20 g/L,特别适合家居儿童房、幼儿园、学校、医院、宾馆等场所的内外墙涂装.

  16. Development of Waterborne Two-component Polyurethane Drawable and Anti-graffiti Wall Coatings%水性双组分聚氨酯可绘画和抗涂鸦涂料的研制

    Institute of Scientific and Technical Information of China (English)

    唐英; 蔡伟; 危春阳

    2015-01-01

    使用水性双组分聚氨酯乳液及固化剂技术开发出具有优异的耐涂鸦性能,和高度环境友好的水性内外墙可擦洗的绘画涂料.研究了水性聚氨酯乳液/固化剂种类、比例、稀释剂水添加量等因素对绘画涂料涂层上涂鸦物质清除性能等的影响,并对比测试了涂料的综合性能,制备出了兼具优异涂鸦清除性能、环保性能、耐擦洗性能、施工性能等综合性能优异的水性内墙绘画涂料.经试验测试,涂层表面能够轻松清除水性白板笔、水彩笔、无尘粉笔等涂鸦物质以及鞋油、墨水、番茄酱、咖啡、红茶等多种生活污渍,涂料的组分达到所有相关的环保标准要求,尤其是挥发性有机化合物(VOC)含量仅为11 g/L,远低于T31/01002-C001—2014《儿童水性内墙涂料》标准中VOC的限制20 g/L,特别适合家居儿童房、幼儿园、学校、医院、宾馆等场所的内外墙涂装.%Waterborne drawable interior and exterior wall coatings were developed with excellent graffiti removal ability, scrub-resistance and application properties by using waterborne two-component polyurethane and curing agent as film-forming substances. The effect of the binder types and the mixing ratios of waterborne polyurethane and curing agent were discussed, including the dosage of water on the graffiti removal ability of the coatings. The marks of this drawable coatings by a water mark pen, water color pen, dustless chalk, shoe polish, ink, tomato juice, coffee and black tea can be easily cleaned. The compositions in this paint meet the requirements of all the related environment standards. In particular, VOC content is only 11 g/L, which is much lower than the VOC limit 20 g/L in T31/01002-C001—2014 for waterborne interior coatings. This product was environmentally friendly and suitable for kids' rooms, kindergarten, schools, hospitals, hotels and public places.

  17. Dynamic structure factors and sum rules in two-component quantum gases with spin-orbit coupling%自旋-轨道耦合作用下双组分量子气体中的动力学结构因子与求和规则

    Institute of Scientific and Technical Information of China (English)

    贺丽; 余增强

    2016-01-01

    Sum rules for the dynamic structure factors are powerful tools to explore the collective behaviors in many-body systems at zero temperature as well as at finite temperatures. The recent remarkable realization of synthetic spin-orbit (SO) coupling in quantum gases is opening up new perspective to study the intriguing SO effects with ultracold atoms. So far, a specific type of SO coupling, which is generated by a pair of Raman laser beams, has been experimentally achieved in Bose-Einstein condensates of 87Rb and degenerate Fermi gases of 40K and 6Li. In the presence of SO coupling, the dynamic structure factors for the density fluctuation and spin fluctuation satisfy different sum rules. In particular, in the two-component quantum gases with inter-species Raman coupling, the f-sum rule for the spin fluctuation has an additional term proportional to the transverse spin polarization. Due to the coupling between the momentum and spin, the first moment of the dynamic structure factor does not necessarily possess the inversion symmetry, which is in strong contrast to the conventional system without SO coupling. Such an asymmetric behavior could be observed in both Fermi gases and Bose gases with Raman coupling. As a demonstration, we focus on the uniform case at zero temperature in this work. For the non-interacting Fermi gases, the asymmetric first moment appears only when the Raman detuning is finite. The asymmetric amplitude is quite limited, and it vanishes at both zero detuning and infinite detuning. For the weakly interacting Bose gases, the first moment is asymmetric in momentum space even at zero detuning, when the ground state spontaneously breaks the Z2 symmetry in the plane-wave condensation phase. Using the Bogoliubov method, the dynamic structure factor and its first moment are explicitly calculated for various interaction parameters. We find that the asymmetric behavior in the spin channel could be much more significant than in the density channel, and the

  18. Simultaneous refinement of two components of an exsolution intergrowth

    DEFF Research Database (Denmark)

    Topa, Dan; Petricek, Vaclav; Dusek, Michal; Makovicky, Emil; Balic Zunic, Tonci

    2008-01-01

    Crystal structures of intergrown lindstromite and krupkaite were determined in two distinct samples by a simultaneous crystal-structure refinement using a modified JANA program package. The exsolution intergrowths have a bulk composition, determined by means of electron microprobe, equal to bd(60...

  19. Characteristics of two-component epoxy modified bitumen

    NARCIS (Netherlands)

    Xiao, Y.; Van de Ven, M.F.C.; Molenaar, A.A.A.; Su, Z.; Zandvoort, F.

    2010-01-01

    Coal tar bearing emulsions were used in the Netherlands as binder in anti-skid surfaces for runways because of their perfect adhesion and fuel resistance properties. They are however toxic and will not be allowed anymore after 2010. Therefore alternatives need to be developed. As one of the alternat

  20. Dynamically Tunable Memory in Two-Component Gene Circuit

    Energy Technology Data Exchange (ETDEWEB)

    Ghim, C; Almaas, E

    2008-09-05

    Cell has the potential to remember the environmental conditions for many (10{sup 7}) generations but stochastic fluctuations set a fundamental limit on the stability of this memory. Here we explicitly take the binding-unbinding of macromolecules into account to propose a novel rationale for the protein-protein interaction in cell physiology. Based on the first-exit time and the corresponding deterministic characterization of various genetic circuits, we show that the reversible binding dynamics may stabilize non-genetically inherited cell states, providing a practical strategy for designing robust epigenetic memory.