Analysis of College Students’ Test Scores Based on Two-Component Mixed Generalized Normal Distribution

In order to improve the fitting accuracy of college students’ test scores, this paper proposes two-component mixed generalized normal distribution, uses maximum likelihood estimation method and Expectation Conditional Maxinnization (ECM) algorithm to estimate parameters and conduct numerical simulation, and performs fitting analysis on the test scores of Linear Algebra and Advanced Mathematics of F University. The empirical results show that the two-component mixed generalized normal distribution is better than the commonly used two-component mixed normal distribution in fitting college students’ test data, and has good application value.

The PhoR/PhoP two-component system regulates fengycin production in Bacillus subtilis NCD-2 under low-phosphate conditions

Bacillus subtilis strain NCD-2 is an excellent biocontrol agent for plant soil-borne diseases,and the lipopeptide fengycin is one of the active antifungal compounds in strain NCD-2.The regulator Pho P and its sensor kinase Pho R compose a two-component system in B.subtilis.In this study,the pho R-and pho P-knockout mutants were constructed by in-frame deletion and the role of Pho R/Pho P on the production of fengycin was determined.Inactivation of pho R or pho P in B.subtilis decreased its inhibition ability against Botrytis cinerea growth in vitro compared to the strain NCD-2 wild type.The lipopeptides were extracted from strain NCD-2 wild type and its mutant strains by hydrochloric acid precipitate,and the lipopeptides from pho R-null mutant or pho P-null mutant almost lost the inhibition ability against B.cinerea growth compared to the lipopeptides from strain NCD-2 wild type.Fast protein liquid chromatography(FPLC) analysis of the lipopeptides showed that inactivation of pho R or pho P genes reduced the production of fengycin by strain NCD-2.The fengycin production abilities were compared for bacteria under low-phosphate medium(LPM) and high-phosphate medium(HPM),respectively.Results indicated that the regulation of fengycin production by the Pho R/Pho P two-component system occurred in LPM but not in HPM.Reverse transcriptional-PCR confirmed that the fengycin synthetase gene fen C was positively regulated by pho P when cultured in LPM.All of these characteristics could be partially restored by complementation of intact pho R or pho P gene in the mutant.These data indicated that the Pho R/Pho P two-component system greatly regulated fengycin production and antifungal ability in B.subtilis NCD-2 mainly under low-phosphate conditions.

Modulational Instability of Trapped Two-Component Bose-Einstein Condensates

The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersion relation is obtained analytically by means of the modified lens-type transformation and linear stability analysis.It is shown that a modulational unstable time scale exists for trapped two-component BECs.The modulational properties-which are determined by the wave number,external trapping parameter,intraand inter-species atomic interactions-are modified significantly.The analytical results are confirmed by direct numerical simulation.Our results provide a criterion for judging the occurrence of instability of the trapped two-component BECs in experiment.

New Soliton Solutions to the Initial Value Problem for the Two-Component Short Pulse Equation

We formulate a matrix Riemann-Hilbert problem to the initial value problem for the two-component system proposed by Matsuno. By solving the associated Riemann-Hilbert problem, we can get the soliton solutions of the two-component system. One and two soliton solutions are investigated in detail.

Preparation and Properties of Two-Component and Double-Crosslinking Waterborne Polyurethane-Acrylic Dispersions

In this paper, isophorone diisocyanate (IPDI), polyethylene glycol (PEG), dimethylolpropionic acid (DMPA) and internal crosslinking agent trimethylolpropane (TMP) were used to prepare waterborne polyurethane. And then double-crosslinked polyurethane-acrylic composite aqueous dispersion was prepared in which polyacrylate was adopted to modify waterborne polyurethane and some special external crosslinking agents were added including silicone and trifunctional aziridine. The influence of the amounts of internal and external crosslinking agents, emulsifier, initiator on the particle size, particle size distribution, viscosity, molecular weight, as well as water adsorption ratio were studied.

Manipulating transition of a two-component Bose–Einstein condensate with a weak δ-shaped laser

We theoretically study the transition dynamics of a two-component Bose-Einstein condensate driven by a train of weak δ-shaped laser pulses. We find that the atomic system can experience peculiar resonant transition even under weak optical excitations and derive the resonance condition by the perturbation method. Employing this mechanism, we propose a scheme to obtain an atomic ensemble with desired odd/even atom number and also a scheme to prepare a nonclassical state of the many-body system with fixed atom number.

VISCOELASTICITY AND IONIC CONDUCTIVITY OF TWO-COMPONENT EPOXY NETWORK CONTAINING LITHIUM PERCHLORATE

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 carded 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 ff 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.

MECHANICAL RELAXATION TIME OF A TWO-COMPONENT EPOXY NETWORKLiClO_4 POLYMER ELECTROLYTE

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 LiCIO4 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 chains, 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.

Interference properties of two-component matter wave solitons

Wave properties of solitons in a two-component Bose-Einstein condensate are investigated in detail.We demonstrate that dark solitons in one of components admit interference and tunneling behavior,in sharp contrast to the scalar dark solitons and vector dark solitons.Analytic analyses of interference properties show that spatial interference patterns are determined by the relative velocity of solitons,while temporal interference patterns depend on the velocities and widths of two solitons,differing from the interference properties of scalar bright solitons.Especially,for an attractive interactions system,we show that interference effects between the two dark solitons can induce some short-time density humps(whose densities are higher than background density).Moreover,the maximum hump value is remarkably sensitive to the variation of the solitons'parameters.For a repulsive interactions system,the temporal-spatial interference periods of dark-bright solitons have lower limits.Numerical simulation results suggest that interference patterns for the dark-bright solitons are more robust against noises than bright-dark solitons.These explicit interference properties can be used to measure the velocities and widths of solitons.It is expected that these interference behaviors can be observed experimentally and can be used to design matter wave soliton interferometer in vector systems.

ESTIMATION OF BLENDING RATIO OF TWO-COMPONENT FIBER BUNDLE FROM BUNDLE LOAD-ELONGATION CURVE

In this paper, two methods were developed to assess the blending ratio of two-componentfiber bundles. They were the peak-height method and the slope method. The relationship be-tween blending ratio and testing data was analysed, and the regression curves were obtained bystepwise regression method. It was pointed out that the testing errors of both methods were lessthan two percent. The validities of both methods were verified by experiments, All calculationsof both methods were completed by computer. The blending ratio was ascertained from the test-ing data of bundle fiber strength tester which was made by the authors themselves.

Stationary Classical Chaos of Trapped Two-Component Bose-Einstein Condensates in 1-D Optical Lattice Potentials

We study the nonlinear dynamics of two-component Bose-Einstein condensates in one-dimensional pe-riodic optical lattice potentials.The stationary state perturbation solutions of the coupled two-component nonlinearSchr?dinger/Gross-Pitaevskii equations are constructed by using the direct perturbation method.Theoretical analysisrevels that the perturbation solution is the chaotic one,which indicates the existence of chaos and chaotic region inparameter space.The corresponding numerical calculation results agree well with the analytical results.By applying thechaotic perturbation solution,we demonstrate the atomic spatial population and the energy distribution of the systemare chaotic generally.

THE GLM REPRESENTATION OF THE TWO-COMPONENT NONLINEAR SCHR?DINGER EQUATION ON THE HALF-LINE

The Gelfand-Levitan-Marchenko representation is used to analyze the initialboundary value problem of two-component nonlinear Schr¨odinger equation on the half-line.It has shown that the global relation can be effectively analyzed by the Gelfand-LevitanMarchenko representation. we also derive expressions for the Dirichlet-to-Neumann map to characterize the unknown boundary values.

Effect of viscosity on stability and accuracy of the two-component lattice Boltzmann method with a multiple-relaxation-time collision operator investigated by the acoustic attenuation model

A two-component lattice Boltzmann method(LBM) with a multiple-relaxation-time(MRT) collision operator is presented to improve the numerical stability of the single relaxation time(SRT) model. The macroscopic and the momentum conservation equations can be retrieved through the Chapman–Enskog(C-E) expansion analysis. The equilibrium moment with the diffusion term is calculated, a diffusion phenomenon is simulated by utilizing the developed model, and the numerical stability is verified. Furthermore, the binary mixture channel model is designed to simulate the sound attenuation phenomenon, and the obtained simulation results are found to be consistent with the analytical solutions. The sound attenuation model is used to study the numerical stability and calculation accuracy of the LBM model. The simulation results show the stability and accuracy of the MRT model and the SRT model under different viscosity conditions. Finally,we study the influence of the error between the macroscopic equation of the MRT model and the standard incompressible Navier–Stokes equation on the calculation accuracy of the model to demonstrate the general applicability of the conclusions drawn by the sound attenuation model in the present study.

Genome-Wide Identification of Two-Component Signal Transduction System Genes in Melon (<I>Cucumis melon</I>L.)

Two-component system (TCS) is responsible for cytokinin signaling, which plays critical roles in plant development and physiological process. This system is generally composed of two signaling factors, a histidine kinase (HK) and a response regulator (RR) that is associated with a histidine phosphotransfer (HP) protein. In this study, we performed systematic investigation on TCS genes in melon (Cucumis melon L.). We identified 44 TCS genes in melon, including 18 HK(L)s (9 HKs and 9 HKLs), 5 HPs (4 authentic and 1 pseudo), and 21 RRs (7 Type-A, 8 Type-B, and 6 pseudo). The classification and structure of these melon TCS members were introduced in detail as well. Our results provided new insights into the characteristics of the melon TCS genes and might benefit their functional study in future.

Blow-Up for a Periodic Two-Component Camassa-Holm Equation with Generalized Weakly Dissipation

In this paper we study a periodic two-component Camassa-Holm equation with generalized weakly dissipation. The local well-posedness of Cauchy problem is investigated by utilizing Kato’s theorem. The blow-up criteria and the blow-up rate are established by applying monotonicity. Finally, the global existence results for solutions to the Cauchy problem of equation are proved by structuring functions.

Orbital stability of two-component peakons

We prove that the two-component peakon solutions are orbitally stable in the energy space.The system concerned here is a two-component Novikov system,which is an integrable multi-component extension of the integrable Novikov equation.We improve the method for the scalar peakons to the two-component case with genuine nonlinear interactions by establishing optimal inequalities for the conserved quantities involving the coupled structures.Moreover,we also establish the orbital stability for the train-profiles of these two-component peakons by using the refined analysis based on monotonicity of the local energy and an induction method.

Dimensional crossover of a Rabi-coupled two-component Bose–Einstein condensate in an optical lattice

Dimensionality is a central concept in developing the theory of low-dimensional physics.However,previous research on dimensional crossover in the context of a Bose-Einstein condensate(BEC)has focused on the single-component BEC.To our best knowledge,further consideration of the two-component internal degrees of freedom on the effects of dimensional crossover is still lacking.In this work,we are motivated to investigate the dimensional crossover in a three-dimensional(3D)Rabi-coupled two-component BEC.The spin degrees of freedom consist of the Rabi-like and inter-and intra-interaction coupling constants.The dimensional crossovers from 3D to 2D or 1D are controlled by the continuous increase of 1D or 2D lattice depth respectively.Then we analyze how the dimensionality of the model system combined with spin degrees of freedom can affect quantum fluctuations.Accordingly,the analytical expressions of the ground-state energy and quantum depletion of the system are obtained.Our results show that the dimensional crossover induces a characteristic 3D to quasi-2D or 1D crossover in the behavior of quantum fluctuations,with an emphasis on the separated effects of Rabi-like and inter-and intra-interaction coupling constants on the quantum fluctuations.Conditions for possible experimental realization of our scenario are also discussed.

Two-component system GacS/GacA,a global response regulator of bacterial physiological behaviors

The signal transduction system of microorganisms helps them adapt to changes in their complex living environment.Two-component system(TCS)is a representative signal transduction system that plays a crucial role in regulating cellular communication and secondary metabolism.In Gram-negative bacteria,an unorthodox TCS consist-ing of histidine kinase protein GacS(initially called LemA)and response regulatory protein GacA is widespread.It mainly regulates various physiological activities and behaviors of bacteria,such as quorum sensing,secondary metabolism,biofilm formation and motility,through the Gac/Rsm(Regulator of secondary metabolism)signaling cascade pathway.The global regulatory ability of GacS/GacA in cell physiological activities makes it a potential research entry point for developing natural products and addressing antibiotic resistance.In this review,we summarize the progress of research on GacS/GacA from various perspectives,including the reaction mechanism,related regulatory pathways,main functions and GacS/GacA-mediated applications.Hopefully,this review will facilitate further research on GacS/GacA and promote its application in regulating secondary metabolism and as a therapeutic target.

A novel tobacco gene coding for a product similar to bacterial two-component regulators

The two-component signaling system has been studied in bacteria. It takes part in signal transduction of adaptive behavior. Recent studies have shown that a similar two-component system is also present in eukaryotes. Examples of this are ETR1 and CKI1 genes which may involve the signal transduction of plant hormone ethylene and cytokinin respectively. The cloning and characterization of a novel gene ( NTHK1 ) fragment from tobacco are presented.Its partial sequence codes for a product which shows similarity to many two-component signaling proteins. Southern blot analysis indicated that there are 2 to 3 copies of NTHK1 gene in tobacco genome (allotetraploid). Homologous genes may also exist in other plants such as Arabidopsis, soybean and spinach. The expression of NTHK1 gene has also been analyzed in tobacco.Further studies on the isolation of full-length cDNA of NTHK1 gene will elucidate more clearly its function in signal perception and transduction.

Tobacco two-component gene NTHK2

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