17,230 research outputs found

    Radioisotopic Biochemical Probe for Extraterrestrial Life Fifth Annual Progress Report

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    Radiosotopic biochemical probe for extraterrestrial life - Gulliver progra

    Quantum motion in superposition of Aharonov-Bohm with some additional electromagnetic fields

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    The structure of additional electromagnetic fields to the Aharonov-Bohm field, for which the Schr\"odinger, Klein-Gordon, and Dirac equations can be solved exactly are described and the corresponding exact solutions are found. It is demonstrated that aside from the known cases (a constant and uniform magnetic field that is parallel to the Aharonov-Bohm solenoid, a static spherically symmetrical electric field, and the field of a magnetic monopole), there are broad classes of additional fields. Among these new additional fields we have physically interesting electric fields acting during a finite time, or localized in a restricted region of space. There are additional time-dependent uniform and isotropic electric fields that allow exact solutions of the Schrodinger equation. In the relativistic case there are additional electric fields propagating along the Aharonov-Bohm solenoid with arbitrary electric pulse shape

    Equation-free modeling of evolving diseases: Coarse-grained computations with individual-based models

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    We demonstrate how direct simulation of stochastic, individual-based models can be combined with continuum numerical analysis techniques to study the dynamics of evolving diseases. % Sidestepping the necessity of obtaining explicit population-level models, the approach analyzes the (unavailable in closed form) `coarse' macroscopic equations, estimating the necessary quantities through appropriately initialized, short `bursts' of individual-based dynamic simulation. % We illustrate this approach by analyzing a stochastic and discrete model for the evolution of disease agents caused by point mutations within individual hosts. % Building up from classical SIR and SIRS models, our example uses a one-dimensional lattice for variant space, and assumes a finite number of individuals. % Macroscopic computational tasks enabled through this approach include stationary state computation, coarse projective integration, parametric continuation and stability analysis.Comment: 16 pages, 8 figure

    The effects of superconductor-stabilizer interfacial resistance on quench of current-carrying coated conductor

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    We present the results of numerical analysis of a model of normal zone propagation in coated conductors. The main emphasis is on the effects of increased contact resistance between the superconducting film and the stabilizer on the speed of normal zone propagation, the maximum temperature rise inside the normal zone, and the stability margins. We show that with increasing contact resistance the speed of normal zone propagation increases, the maximum temperature inside the normal zone decreases, and stability margins shrink. This may have an overall beneficial effect on quench protection quality of coated conductors. We also briefly discuss the propagation of solitons and development of the temperature modulation along the wire.Comment: To be published in Superconductor Science and Technology. This preprint contains one animated figure (Fig. 6(a)). when asked whether you want to play the content, click "Play". Acrobat Reader (Windows and Mac, but not Linux) will play embedded flash movies. In the printed copy Fig. 6(b) will show the temperature profile at gamma t=15

    Dependence of effective spectrum width of synchrotron radiation on particle energy

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    For an exact quantitative description of spectral properties in the theory of synchrotron radiation, the concept of effective spectral width is introduced. In the classical theory, numeric calculations of effective spectral width (using an effective width not exceeding 100 harmonics) for polarization components of synchrotron radiation are carried out. The dependence of the effective spectral width and initial harmonic on the energy of a radiating particle is established

    Effective spectrum width of the synchrotron radiation

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    For an exact quantitative description of spectral properties of synchrotron radiation (SR), the concept of effective width of the spectrum is introduced. In the most interesting case, which corresponds to the ultrarelativistic limit of SR, the effective width of the spectrum is calculated for the polarization components, and new physically important quantitative information on the structure of spectral distributions is obtained. For the first time, the spectral distribution for the circular polarization component of the SR for the upper half-space is obtained within classical theory

    Fractals and Scars on a Compact Octagon

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    A finite universe naturally supports chaotic classical motion. An ordered fractal emerges from the chaotic dynamics which we characterize in full for a compact 2-dimensional octagon. In the classical to quantum transition, the underlying fractal can persist in the form of scars, ridges of enhanced amplitude in the semiclassical wave function. Although the scarring is weak on the octagon, we suggest possible subtle implications of fractals and scars in a finite universe.Comment: 6 pages, 3 figs, LaTeX fil

    The effects of superconductor-stabilizer interfacial resistance on quench of a pancake coil made out of coated conductor

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    We present the results of numerical analysis of normal zone propagation in a stack of YBa2Cu3O7xYBa_2Cu_3O_{7-x} coated conductors which imitates a pancake coil. Our main purpose is to determine whether the quench protection quality of such coils can be substantially improved by increased contact resistance between the superconducting film and the stabilizer. We show that with increased contact resistance the speed of normal zone propagation increases, the detection of a normal zone inside the coil becomes possible earlier, when the peak temperature inside the normal zone is lower, and stability margins shrink. Thus, increasing contact resistance may become a viable option for improving the prospects of coated conductors for high TcT_c magnets applications.Comment: 9 pages, 4 figure

    Inclusive production in a QCD and N=4 SYM motivated model for soft interactions

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    The results presented in this paper differ from our previous unsuccessful attempt to predict the rapidity distribution at W=7TeVW = 7 \,TeV. The original version of our model (GLMM) only summed a particular class of Pomeron diagrams (enhanced diagrams). We believe that this was the reason for our failure to describe the 7TeV7 \,TeV inclusive LHC data. We have developed a new approach (GLM) that also includes the summation of the semi-enhanced diagrams.This contribution is essential for a successful description of the inclusive distributions, which is presented here.Comment: 4 pages, 3 figure
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