Euler-Lagrange Forms and Cohomology Groups on Jet Bundles

Using the language of jet bundles, we generalize the definitions of Euler-Lagrange one-form and the associated cohomology which were introduced by Guo et al. [Commun. Theor. Phys. 37 (2002) 1]. Continuous and discrete Lagrange mechanics and field theory are presented. Higher order Euler-Lagrange cohomology groups are also introduced.     

Effects of Impact Parameter on Isospin Fractionation in Heavy Ion Collision at Intermediate Energies

We calculated the degree of isospin fractionation (N/Z)n/(N/Z)Nfrag by using the isospin dependent quantum molecular dynamics model (IQMD), where (N/Z)n and (N/Z)Nfrag are the saturated neutron to proton ratio of nucleon emissions and that of the fragment emissions respectively. In general, the observable in nuclear reaction is very sensitive to impact parameter. So it is interesting to investigate the dependence of (N/Z)n/(N/Z)Nfrag on the impact parameter b. Fig.1 shows the value of (N/Z)n/(N/Z)Nfrag as a function of impact parameter b for four different cases:     

Direct Measurements of E×B Flow and Its Impact on Edge Turbulence in the CASTOR Tokamak Using an Optimized Gundestrup Probe

New experimental evidence of the correlation between edge sheared E×B flow and reduction of turbulence has been measured in the CASTOR tokamak (R = 0.4 m, a = 0.085 m, B _T = 1 T). A biasing electrode is placed at the separatrix in a configuration which has demonstrated strongly sheared electric fields and consequent improvement of the global particle confinement. A set of movable electrostatic probes (rake, Langmuir, Gundestrup, and rotating Mach) provide redundant, simultaneous measurements of poloidal flow, toroidal flow, electron temperature, density, and radial electric field with high temporal resolution and at the same poloidal location. Particular effort has been made in the optimization of the Gundestrup probe collector geometry in order to reduce the relative uncertainty of Mach number measurements in plasmas with weak flow (M , M < 0.1). The measurements from the rake, Gundestrup, and rotating Mach probes give three independent radial profiles of E×B shear in ohmic and biased modes. Good agreement is obtained both for the profile shape and its absolute magnitude. The plasma flows, especially the poloidal E×B drift velocity, are strongly modified in the sheared region, reaching Mach numbers as high as half the sound speed. The corresponding shear rates (5×10⁶ s^-1) derived from both the flow and electric field profiles are in excellent agreement and are at least an order of magnitude higher than the growth rate of unstable turbulent modes as estimated from fluctuation measurements. In addition, we compare the measured E×B ion mass flow with the phase velocity of fluctuations moving poloidally across the Gundestrup collectors. Given the poloidal separation of the collecting plates and the sampling frequency (5 MHz), the maximum detectable phase velocity turns out to be rather modest compared to the measured bulk poloidal flow speed. Therefore the two quantities are only compared when the poloidal speed is low; in that case, they show similar behaviour in response to the applied bias.     

An Estimation for the Power-Law Distribution Parameter Based on Entropy

A new estimation based on the Shannon entropy for the power-law distribution parameter is presented, The maximum likelihood estimation （MLE） of the parameter is discussed and the relation between the MLE and the moment estimation of the parameter is given out. It is shown that the minimum Shannon entropy estimation is equivalent to the MLE giving the log expectation.     

Impact of Slip Cycles on the Operation Modes and Efficiency of Molecular Motors

Kinesin is a motor molecule that moves processively on microtubule tracks and is involved in active intracellular transport processes. For small loads, it is powered by the hydrolysis of one ATP molecule per step. Here we extent our previously introduced network theory in order to study the possibility of two different mechanical stepping transitions and the general behavior of the motor’s efficiency. Our theory shows explicitly how chemical and mechanical slip cycles emerge that weaken the coupling between ATP hydrolysis and mechanical stepping. Near chemomechanical equilibrium, the motor efficiency η may vary between η=1 for tight coupling and η=0 for loose coupling, depending on the relevance of the slip cycles. Far from chemomechanical equilibrium, on the other hand, the motor efficiency is found to decay as 1/Δμ with increasing Δμ irrespective of the presence of slip cycles, where Δμ represents the reaction free enthalpy or chemical potential difference per ATP hydrolysis.     

Studies on the Aero-optical Phenomena of Free-vortex Aerodynamic Window′s Jet

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Critical Analyses of Order Parameter and Phase Transitions at High Density in Gross－Neveu Model

By critical analyses of the order parameter of symmetry breaking, we have researched the phase transitions at high density in D = 2 and D = 3 Gross-Neveu (GN) model and shown that the gap equation obeyed by the dynamical fermion mass has the same effectivenesss as the effective potentials for such analyses of all the second order and some specJal first order phase transitions. In the meantime we also further ironed out a theoretical divergence and proven that in D = 3 GN model a first order phase transition does occur in the case of zero temperature and finite chemical potential.     

Intraband Relaxation and Its Influences on Quantum Dot Lasers

A comprehensive two-level numerical model is developed to describe carrier distribution in a quantum-dot laser. Light-emission spectra with different intraband relaxation rates (2 ps, 7.5 ps and 20 ps) are calculated and analysed to investigate the influence of relaxation rates on performance of the quantum-dot laser. The results indicate that fast intraband relaxation favours not only the ground state single mode operation but also the higher injection efficiency.     

Jet production rates at LEP and the scale of αs

We discuss the scale dependence of _s in connection with jet multiplicities on theZ pole in the framework of perturbative QCD. Several scale defining procedures are applied to jet fractions and compared to recent measurements at LEP.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday     

Structure of Callisto and Ice Holes on Its Surface

The discovery of the induced magnetic field of Callisto that is a satellite of Jupiter has been interpreted as evidence for a subsurface salty liquid-water ocean,so we consider a layered structure of callisto,i.e.,a rock-metal core,an outer layer of ice and a middle layer of ocean.For the rock-metal core we try to indicate how the temperature,pressure and mass density depend on the depth.Due to motionn across the magnetic field of Jupiter in a plasma environment,the ice shell of Callisto must be broken down by electric current.     

Effect of Quenching on the Grain Boundary Relaxation in PM2000 ODS Alloy

Grain boundary relaxation in a Fe-based ODS alloy is studied by internal friction measurements. It is found that a grain-boundary peak appears at a lower temperature in the quenched specimens than that in the annealed specimens. The activation energy of the peak is H=2.82±0.11 eV for the former while H = 2.53±0.08 eV for the latter. In addition, a new relaxation peak is observed at the high temperature side of the grain boundary peak in the quenched specimens with an activation energy of 4.41±0.25 eV. The height of the peak increases with increasing quenching temperature. The results suggest that both the shift of the grain-boundary peak and the appearance of the new peak are due to increasing vacancies by quenching that are favourable for the motion of the grain boundaries.     

Fluorescence Quenching of Eu3+ in Organic Solvents. Quenching Effect of the →C-H and -O-H Groups

The extremely weak fluorescence of the rare-earth ions in aqueous solutions is enhanced considerably by replacing H₂O with D₂O (1,2).     

A note on ■_c(3055)~ and ■_c(3123)~

The Babar Collaboration announced two new excited charmed baryons■_c(3055)~ and■_c(3123)~ . We study their strong decays assuming they are D-wave states.Some assignments are excluded by comparing our numerical results with the experimental values of the total widths of ■_c(3055)~ and■_c(3123)~ .We also suggest some possible decay modes,which will be helpful to determine the properties of■_c(3055)~ and■_c(3123)~ .     

Impact of iron composition on the calculated electronic and magnetic properties of Fe3−xNixSi

ABSTRACT

The structural, electronic and magnetic properties of Fe_3?xNi_xSi alloys with variable iron composition (0?≤?x?≤?1) have been investigated within by using Projector augmented wave (PAW) method. The exchange–correlation potential was treated with the generalised gradient approximation (GGA) for the calculation of the structural properties and for the computation of the electronic and magnetic properties in order to treat the d states. These alloys crystallize in cubic Heusler structures; The Fe₃Si and Fe₂NiSi have a regular structure DO₃ and L2₁ respectively. To describe the experimental proprieties we use the on-site Coulomb interactions of U_eff(Ni)?=?3.1?eV and U_eff(Fe)?=?3.4?eV. A good agreement between calculated and experimental magnetic moments is found for the cubic Heusler phases without the addition of Hubbard-model. The obtained results of the density of states and the spin-polarized band structure show that the Fe₂NiSi alloy has half-metallic property. Through the obtained values of the total spin magnetic moment, we conclude that in general, the Fe₂NiSi alloy is half-metallic ferromagnet material whereas the Fe₃Si alloy has a metallic nature.     

Erratum to: Dependence of the Spin-Wave Resonance Spectra in Ferrite–Garnet Films on the Microwave Field Frequency and Damping Parameter

Journal of Experimental and Theoretical Physics - erratum     

Critical Exponents for the Re-entrant Phase Transitions in the Three-Dimensional Blume-Emery-Grifilths Model on the Cellular Automaton

The critical behaviour of the three-dimensional Blume-Emery-Griffiths （BEG） model ＆ investigated at D/ J = O, -0.25 and -1 in the range of-1 ≤ K/J ≤ 0 for J -- 100. The simulations are carried out on a simple cubic lattice using the heating algorithm improved from the Creutz cellular automaton （CCA ） under periodic boundary conditions. The universality of the model are obtained for re-entrant and double re-entrant phase transitions which occur at certain D/J and K/J parameters, with J and K representing the nearest-neighbour bilinear and biquadratic interactions, and D being the single-ion anisotropy parameter. The values of static critical exponents β, γ and v are estimated within the framework of the finite-size scaling theory. The results are compatible with the universal Ising critical behaviour for all continuous phase transitions in these ranges.     

Influence of Gauss-Bonnet Coupling Parameter on?the?Thermodynamic Properties of?Einstein-Gauss-Bonnet and?Einstein-Yang-Mills-Gauss-Bonnet Black Holes

This paper deals in the thermodynamic properties of Einstein-Gauss-Bonnet and Einstein-Yang-Mills-Gauss-Bonnet black holes. It exhibits the various stable and unstable phases of the black holes in these two modified gravity theories. In the first section, that reveals the various aspects of Einstein-Gauss-Bonnet black holes, we chose to study the changes in the Hawking Temperature with variations in the radius of event horizon (r) and charge (Q); and tried to justify them physically. Secondly in case of Einstein-Yang-Mills-Gauss-Bonnet black holes, we have attempted to compare the changes in the various thermodynamic parameters with varying r and Q; with the Einstein-Gauss-Bonnet black holes at a macroscopic level. Here we have considered the Yang Mills tensor, electromagnetic Lagrangian added to the action integrand. Again this very work deals in drawing out the similarities between these two types of black holes, thereby throwing some light on the aspect of black hole stability. Later we have also introspected the effects of the Gauss-Bonnet coupling parameter α, whose function (6αr), is added as a correction term to the black hole entropy. We have especially focused on what changes does it have upon the nature of the plots as to whether it enhances or reduces the effect of Q on the behavior of the curves. Finally this paper has also kept an eye at estimating the stability domains of the black holes described in these two gravity theories.     

Viscosity and Temperature Effects on the Rate of Oxygen Quenching of Tris-(2,2′-bipyridine)ruthenium(II)

We compare the bimolecular quenching rate constant (k₂) of luminescent tris(2,2′-bipyridine)ruthenium(II) by oxygen in water, ethylene glycol and glycerol as a function of temperature and viscosity to several theoretical models. The Smoluchowski equation with experimentally determined diffusion coefficients produced calculated values that were in the best agreement with experiment. For the less viscous solvent, water, this equation produced a value that was approximately an order of magnitude larger than the experimental value. With an increase in solvent viscosity, the Smoluchowski value approached the experimental value. Using the Smoluchowski equation with calculated diffusion coefficients based on the known radii of the reacting species produced deviations an order of magnitude larger in water and a factor of two or three lower in ethylene glycol and glycerol. If an assumption is made that the radii of both molecules are equal, we have the Stokes Einstein equation, and the only parameters become temperature and viscosity. Using this relationship, the calculated values for water are about a factor of two larger and with ethylene glycol and glycerol about a factor of 6 smaller than experimental data. These results show that bimolecular quenching is a more complex process affected by many parameters such as solvent cage effects in addition to viscosity and temperature.