Electroconvection under injection from cathode and heating from above

We study the electroconvection that appears in a nonuniformly heated, poorly conducting liquid in a parallel-plate horizontal capacitor due to the action of an external static electric field on the charge injected from the cathode. It is shown that the heating of the layer from above prevents steady-state convection and that, unlike the isothermal situation, electroconvection can appear in the oscillatory manner as a result of direct Hopf bifurcation. The effect of the heating intensity, the intensity of charge injection from the cathode, and the charge mobility on the thresholds of oscillatory and monotonic electroconvection is analyzed and the characteristic scales and frequencies of critical perturbations are determined. The nonlinear wave and steady-state regimes of the 2D convective structures formed in the poorly conducting liquid under the action of thermogravitational and injection mechanisms of convection are analyzed. The domains of existence of standing, traveling, and modulated waves are determined.     

Transition from free to interacting composite fermions away from

Spin excitations from a partially populated composite fermion level are studied above and below nu=1/3. In the range 2/7相似文献   

Photonuclear fission from high energy electrons from ultraintense laser-solid interactions

A new regime of laser-matter interactions in which the quiver motion of plasma electrons is fully relativistic, with energies extending well above the threshold for nuclear processes, is studied using a petawatt laser system. In solid target experiments with focused intensities exceeding 10(20) W/cm(2), high energy electron generation, hard bremsstrahlung, and nuclear phenomena have been observed. We report here a quantitative comparison of the high energy electrons and the bremsstrahlung spectrum, as measured by photonuclear reaction yields, including the photoinduced fission of 238U.     

Nearest-neighbour interaction from an Abelian symmetry and deviations from Hermiticity

We show that Nearest-Neighbour Interaction (NNI) textures for the quark mass matrices can be obtained through the introduction of an Abelian flavour symmetry. The minimal realisation requires a Z₄${\mathsf{Z}}_4$ symmetry in the context of a two Higgs doublet model. It is further shown that the NNI textures can be in agreement with all present experimental data on quark masses and mixings, provided one allows for deviations of Hermiticity in the quark mass matrices at the 20% level.     

Extracting continuum electron dynamics from high harmonic emission from molecules

We show that high harmonic generation is the most sensitive probe of rotational wave packet revivals, revealing very high-order rotational revivals for the first time using any probe. By fitting high-quality experimental data to an exact theory of high harmonic generation from aligned molecules, we can extract the underlying electronic dipole elements for high harmonic emission and uncover that the electron gains angular momentum from the photon field.     

Curvature from spin

We show that, considering the dislocation defect induced by torsion in spacetime, which behaves like a string with tension, we are lead also to defect angle and then to curvature of spacetime. The space with torsion and curvature is then equivalent to an elastic continuum which has undergone plastic deformations and, following Sakharov idea of the spacetime as a elastic continuum, we are lead to a gravitational constant, which occurs in the Einstein action, as the metrical elasticity of spacetime with the exact value without introducing any arbitrary cutoff, when also torsion is considered.     

Energy from biomass

The potential future bioenergy contribution to the global energy supply is outlined. Severe constraints have to be applied since biomass is used for many different purposes. It is likely that biofuels from primary agricultural products may not increase much above the current 1% of all liquid motor fuels in order to secure food for people and cattle. Bioenergy from forestry should only be used whereever it is absolutely essential. Deforestation results in a net emission of CO₂ to the atmosphere that is equal to that of the USA. Rather than to replace fossil fuels by forest bioenergy, deforestation must be halted. The management of the Swedish annual forest growth shows how a carbon sink can be developed in parallel with biomass for energy and industry. The most promising way of getting energy from biomass is to use the residues in forestry and agriculture. If this is properly done the current annual global bioenergy may double from its present value of 13,000 TWh in the next few decades.     

Degeneracy from quadric cones for projective reconstruction from two views

Fundamental matrix encapsulates all the geometric information in two views, and it plays an important role in many applications of three-dimensional computer vision. However, some configurations have an inherent ambiguity, namely, degeneracy, and no matter how many matched image points are used, the fundamental matrix could not be determined uniquely. It is well-known that degeneracies occur when all the space points and both the camera centers belong to a ruled quadric. But it is not so well-known how great the degenerate degrees in different configurations are. In this paper, we discuss the degeneracies caused by a quadric cone and give the corresponding degenerate degrees. We parameterize all the points on a quadric cone by a twisted cubic lying on the cone, and obtain a parametric coefficient matrix of the equations for estimating the fundamental matrix. By analyzing the coefficient matrix, we get the rank of it, i.e. the degenerate degree of the given configuration. It gives a more intuitive degeneracy and the degenerate degrees of the configurations, and reveals the full picture of the degeneracies on a cone.     

Hadrons from jets

A dynamical ansatz on the nature of the interaction that binds the constituents into physical hadrons makes it possible to compute perturbatively the spectrum and the quantum numbers of hadrons near the phase space boundary of a QCD jet. Nonperturbative effects are important for less extreme values of the momentum of the detected hadrons. They can be incorporated in the model using the algorithm of the jet calculus.     

Bremsstrahlung from solitons

One dimensional solitons behave like Newtonian particles if subjected to external forces, as has been shown by Fogel et al. for the case of sine-Gordon solitons. We add here the observation that they also emit free radiation—i.e. Bremsstrahlung—if accelerated by an external force. The radiation spectrum is calculated for the sine Gordon case.Work supported in part by the National Science Foundation, Grant DMR 74-23494 and in part by a travel grant from the KFA Jülich