Generation and classification of the translational shape-invariant potentials based on the analytical transfer matrix method

For the conventional translational shape-invariant potentials (TSIPs), it has demonstrated that the phase contribution devoted by the scattered subwaves in the analytical transfer matrix quantization condition is integrable and independent of n. Based on this fact we propose a novel strategy to generate the whole set of conventional TSIPs and classify them into three types. The generating functions are given explicitly and the Morse potential is taken as an example to illustrate this strategy.     

Algorithms for Improving the Quality of R-Trees

A novel approach to operation with a structure for spatial indexing of extended objects shaped as R-trees is considered. It consists of the initial global construction of an efficient R-tree structure and the subsequent operation with it using conventional dynamic algorithms. A global strategy for constructing an R-tree reduced to a problem of dividing a set of rectangular objects into K parts with minimum mutual overlay is suggested. Base, box, and Divide and Conquer algorithms are suggested. The results of experimental modeling of the execution of various algorithms are discussed.     

Statistical analysis of the evolutionary minority game with different capacities

In this paper we consider the evolutionary minority game with different capacities. With the increase of capacity level ρ₁, the probability γ_n of room1 with n agents changes from one normal distribution to two normal distributions and back to one normal distribution again. When room2 is the basic strategy, the probability of room1 with n agents is a small normal distribution. And when room1 is the basic strategy the probability of room1 with n agents is a large normal distribution. We calculate the integral of the normal distributions and explain the characters in the figures. For instance, the room with more capacity represents the interest of the majority and the room has more probability to win.     

Cascade defense via navigation in scale free networks

In this paper, we investigate cascade defense and control in scale free networks via navigation strategy. It is found that with an appropriate parameter a, which is tunable in controlling the effect of degree in the navigation strategy, one can reduce the risk of cascade break down. By checking the distribution of efficient betweenness centrality (EBC) and the average EBC of vertices with degree k, the validity can be guaranteed. Despite the advantage of cascade defense, the degree based navigation strategy may also lead to lower network efficiency. To avoid this disadvantage, we propose a new navigation strategy. Importantly and interestingly, the new strategy can defend cascade break down effectively even without reducing the network efficiency. Distribution of the EBC and EBC-degree correlation of the new strategy are also investigated to explain the effectiveness in cascade defense.     

Asymptotic behaviour of the Fourier coefficients of MAPW wave functions

In contrast to the conventional APW method the MAPW method imposes continuity conditions on the trial wave functions which guarantee that the wave functions and their first derivatives are continuous throughout the whole atomic polyhedron. It is shown that as a consequence of this fact the Fourier coefficients of the MAPW wave functions approach zero as 1/p ⁴ whereas conventional APW functions decay as 1/p ² only. For the MAPW Fourier coefficients asymptotic formulas are derived that may be useful in numerical calculations. Numerical results are given for metallic Li and Cu.     

Determination of the chemical diffusion coefficient by Monte Carlo simulation of the center-of-mass propagation

The extendedZwerger method of determining thechemical diffusion coefficient, for lattice gasconventional diffusion in equilibrium andsuperdiffusion in stationary state, isverified by Monte Carlo simulation of thecentre-of-mass propogation. It has been found that the chemical diffusion coefficient for superdiffusion in one-dimensional, noninteracting lattice gas with the exclusion of double occupancy isconcentration independent like in conventional diffusion. Moreover, it has been proved that (chemical) superdiffusion ofuncorrelated particles isexactly described in this model by theBurgers nonlinear diffusion equation.     

New 4H silicon carbide metal semiconductor field-effect transistor with a buffer layer between the gate and the channel layer

A new 4H silicon carbide metal semiconductor field-effect transistor (4H-SiC MESFET) structure with a buffer layer between the gate and the channel layer is proposed in this paper for high power microwave applications. The physics-based analytical models for calculating the performance of the proposed device are obtained by solving one- and two-dimensional Poisson's equations. In the models, we take into account not only two regions under the gate but also a third high field region between the gate and the drain which is usually omitted. The direct-current and the alternating-current performances for the proposed 4H-SiC MESFET with a buffer layer of 0.2 μ m are calculated. The calculated results are in good agreement with the experimental data. The current is larger than that of the conventional structure. The cutoff frequency (f_T) and the maximum oscillation frequency (f_max) are 20.4 GHz and 101.6 GHz, respectively, which are higher than 7.8 GHz and 45.3 GHz of the conventional structure. Therefore, the proposed 4H-SiC MESFET structure has better power and microwave performances than the conventional structure.     

The Role of Time in Relational Quantum Theories

We propose a solution to the problem of time for systems with a single global Hamiltonian constraint. Our solution stems from the observation that, for these theories, conventional gauge theory methods fail to capture the full classical dynamics of the system and must therefore be deemed inappropriate. We propose a new strategy for consistently quantizing systems with a relational notion of time that does capture the full classical dynamics of the system and allows for evolution parametrized by an equitable internal clock. This proposal contains the minimal temporal structure necessary to retain the ordering of events required to describe classical evolution. In the context of shape dynamics (an equivalent formulation of general relativity that is locally scale invariant and free of the local problem of time) our proposal can be shown to constitute a natural methodology for describing dynamical evolution in quantum gravity and to lead to a quantum theory analogous to the Dirac quantization of unimodular gravity.     

Influence of the Stark effect on multiphoton ionization of atoms when the dynamic polarizability depends strongly on the laser frequency

The influence of the Stark effect on multiphoton ionization of Ba atoms under conditions when the dynamic polarizability depends strongly on the frequency of the laser radiation is investigated. It is found that for some electric field strengths ε of the laser radiation this effect gives rise to resonance peaks in the Ba⁺ ion yield as a function of the laser radiation frequency at frequencies corresponding to single-photon transitions between the excited states. These frequencies can differ substantially from the frequencies corresponding to the conventional multiphoton excitation of these states from the ground states of the atoms. Peaks in the ion yield as a function of ε behave differently from the conventional Stark effect—their position on the frequency scale does not depend strongly on ε. The conditions under which such an induced resonance structure appears are determined. Zh. éksp. Teor. Fiz. 113, 499–512 (February 1998)     

Effect of ultrasound on the structural and textural properties of copper-impregnated cerium-modified zirconium-pillared bentonite

In this study, the synthesis of zirconium-pillared bentonite modified with cerium was performed via two different methods by the application of conventional and ultrasonic treatments during the intercalation stage. To synthesise copper-impregnated pillared clays by wet impregnation, cerium-modified zirconium-pillared clays were used as supportive materials after being calcined at 300 °C. Ultrasonic treatment significantly decreased the required processing time compared with the conventional treatment of the synthesised pillared bentonites. Chemical analysis confirmed the incorporation of Zr⁴⁺, Ce⁴⁺ and Cu²⁺ species into the pillared bentonites. X-ray diffraction (XRD) patterns of zirconium- and cerium/zirconium-pillared bentonites prepared by conventional treatment show that one large d-spacing above 3.5 nm corresponds to the mesoporous delaminated part, and another small d-spacing above 1.7 nm is indicative of the microporous pillared part. Zirconium- and cerium/zirconium-pillared bentonites prepared via ultrasonic treatment exhibited similar results, with the same high d-spacing but with a second low-intensity d-spacing above 1.9 nm. The delaminated structures of the pillared bentonites synthesised by both methods were conserved after copper impregnation. Nitrogen-adsorption isotherm analysis showed that the textural characteristics of products synthesised by ultrasonic treatment were comparable to those of products synthesised by conventional treatment. Fourier-transform infrared spectroscopy (FTIR) analyses showed the presence of Brønsted- and Lewis-acid sites, and zirconium-pillared clays synthesised by conventional treatment exhibited increased numbers of Brønsted- and Lewis-acid sites after cerium addition and copper impregnation. However, the products synthesised by ultrasonic treatment exhibited an increased number of Brønsted- and Lewis-acid sites after cerium addition, but a decreased number of acid sites after copper impregnation.     

A 2-stage strategy updating rule promotes cooperation in the prisoner's dilemma game

In this study,we propose a spatial prisoner’s dilemma game model with a 2-stage strategy updating rule,and focus on the cooperation behavior of the system.In the first stage,i.e.,the pre-learning stage,a focal player decides whether to update his strategy according to the pre-learning factor β and the payoff difference between himself and the average of his neighbors.If the player makes up his mind to update,he enters into the second stage,i.e.,the learning stage,and adopts a strategy of a randomly selected neighbor according to the standard Fermi updating rule.The simulation results show that the cooperation level has a non-trivial dependence on the pre-learning factor.Generally,the cooperation frequency decreases as the pre-learning factor increases;but a high cooperation level can be obtained in the intermediate region of 3 < β < 1.We then give some explanations via studying the co-action of pre-learning and learning.Our results may sharpen the understanding of the influence of the strategy updating rule on evolutionary games.     

Implementation of corner-free truncation strategy in DGTD method

In this paper, the corner-free truncation (CFT) strategy for analyzing certain geometries is proposed within the framework of Discontinuous Galerkin Time Domain. The proposed algorithm used scalene ellipsoid boundary, and it is universal for any ellipsoid (sphere, spheroid, and scalene ellipsoid). The advantage of this proposed algorithm is that it allows semi-principal axes (a, b, c) that can be different. Compared with spheroid or sphere, scalene ellipsoid can be easily adjusted to match certain geometries and reduces computational cost. The accuracy and efficiency of the proposed CFT strategy is verified by numerical examples.     

Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 ± 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle–antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.     

Parallelized sampling of the Gibbs ensemble

An expression for the probability distribution of NVT-like sub-ensembles constituting the Gibbs ensemble is derived. Knowledge of this distribution makes it possible to carry out the simulation without the explicit exchange of real particles between the simulation boxes and to evaluate directly any Gibbs ensemble average from a series of independent simultaneous simulations (Monte Carlo or molecular dynamics) performed on a set of NVT-likt sub-ensembles with the fixed distribution of particles. An implementation of the method, which is tailored mainly for complex systems, is exemplified for the square-well fluid, and its efficiency and results are compared with those obtained from the conventional Gibbs ensemble simulations.     

Summing all the eikonal graphs. II

A physically reasonable model is introduced in order to estimate, in a functional way, the vast number of distinct graphs which are conventionally neglected in eikonal scattering models that lead to total cross sections increasing with energy in the form of the Froissart bound. A range of estimates of non-leading-log effects on the conventional, leading-log, ladder-tower graphs is also attempted. Upon summing all the eikonal graphs of this model, one finds significant cancellations away from the conventional, tower-graph result, with total cross sections tending to constant values at extreme scattering energies on the order of 10³-10⁶ TeV.Received: 6 November 2003, Published online: 12 November 2003     

Exact solution of the simplified hubbard model

We present the exact solution of the simplified Hubbard model in which only one kind of electrons can hop and this quantum mechanical hopping of electrons is assumed to be unconstrained. It is shown that the model still behaves nontrivially, although it no longer depends on the lattice structure and the dimensionality of the system. For this case we find: (i) a gap in the ground state energy always exists at the half-filled band point (n=1), (ii) a preferred magnetic state atn=1 and largeU is a total spin singlet, (iii)U-dependence of the ground state energy has qualitatively the same form as one of the conventional Hubbard model with the (t ²/U)-behavior at largeU. A phase diagram of the model is discussed.     

Effect of high hydrostatic pressure on the profile of proteins extracted from Betula pendula pollens

High hydrostatic pressure (HHP) has high success potential in pollen protein extraction, but its effect on pollen protein profiles has not been studied yet. The aim of this study is to put forward whether HHP processing causes a change in the protein profiles extracted from pollens or not. In this study, proteins extracted from Betula pendula pollens were studied at 100, 200 and 300?MPa at room temperature for 5?min. In addition, the efficiency of three different extraction solvents, namely phosphate buffer saline (PBS) buffer pH 7.5, trichloroacetic acid–acetone and Tris–HCl buffer pH 8.8, was also observed, and the results were compared with the conventional pollen protein extraction procedure. As a result, it is concluded that 200?MPa for 5?min has extracted similar amounts of protein compared with the conventional extraction method which lasted for 24?h, which lasted for 24 h. On the other hand, the application time for 200 MPa for 5 min is extremely shorter when it is compared to the conventional extraction method.     

An Efficacious Target-Field Approach to Design Shim Coils for Halbach Magnet of Mobile NMR Sensors

The main magnetic fields of mobile nuclear magnetic resonance (NMR) magnets differ from those of conventional NMR and magnetic resonance imaging (MRI) magnets. In the Halbach magnet, the main field B ₀ is perpendicular to the longitudinal axis, the symmetry of the current distribution with respect to the symmetry of the magnetic field differs from that in conventional target-field applications, and the current distribution on the coil surface cannot be expressed in terms of periodic basis functions. To obtain the winding pattern of the coil, an efficacious target-field approach. The surface of a coil is divided into small discrete elements, where each element is represented by a magnetic dipole. From the stream function of the elements, the resultant magnetic field is calculated. The optimization strategy follows an objective function defined by the power dissipation or efficiency of the coil. This leads to the optimum stream function on the coil surface, whose contour lines define the winding patterns of the coil. This paper shows winding patterns designed of shim coils for Halbach magnet and illustrates the craft of a shim coil using flexible printed circuit board. The performance of the coils is verified by simulating the fields they produce over the sensitive volume.     

Mutated and converged damping factors in lens system optimization to find new local minima

In this paper, we proposed a strategy to find new local minima based on mutated damping factors and converged damping factor (conventional damping factor). In this proposed strategy, the converged damping factor is used to make the algorithm converge to a certain local minimum, and the mutated damping factors are used to make the trapped solution jump out of present convergence area. We study the behavior of the two kinds of factors in lens system optimization. The proposed strategy is successfully applied in lens system optimization. The result shows that the proposed strategy is reliable to make a further improvement especially when the solution is approaching target design.