2,306 research outputs found
Broken ergodicity in driven one-dimensional particle systems with short-range interaction
We present a one-dimensional nonequilibrium model for a driven
diïżœusive system which has local interactions and slow nonconservative reaction
kinetics. Monte-Carlo simulations suggest that in the thermodynamic limit
the steady state exhibits a phase with broken ergodicity. We propose a hydrodynamic
equation for the coarse-grained density (under Eulerian scaling),
augmented by a prescription how to treat shock and boundary discontinuities,
respectively. This conjecture can be readily generalized to other weakly nonconservative
driven diïżœusive systems and is supported by a heuristic identiïżœcation
of the main dynamical mode that governs the microscopic dynamics, viz. the
random motion of a shock in an self-organized eïżœective potential. This picture
leads to the exact phase diagram of the system and suggests a novel and
mathematically tractable mechanism for \freezing by heating"
Underlying Event Studies for LHC Energies
Underlying event was originally defined by the CDF collaboration decades ago.
Here we improve the original definition to extend our analysis for events with
multiple-jets. We introduce a definition for surrounding rings/belts and based
on this definition the jet- and surrounding-belt-excluded areas will provide a
good underlying event definition. We inverstigate our definition via the
multiplicity in the defined geometry. In parallel, mean transverse momenta of
these areas also studied in proton-proton collisions at TeV LHC
energy.Comment: 6 pages and 4 figure
Domain-wall coercivity in ferromagnetic systems with nonuniform local magnetic field
Domain-wall (DW) coercive field, H-CW, which characterizes pinning of DW's in soft magnetic materials, decreases strongly with increasing value of gradient, G, of the effective local DW-position-restoring magnetic field. Particular shapes of the dependence, H-CW(G), can be calculated from the mean energy dissipation of the DW moving over the particular profile of the DW pinning field, H-p. In this paper, H-CW(G) is calculated from a wall-pinning field, H-p, which is expressed as a stochastic function of the DW coordinate, x(DW). The wall-pinning field, H-p, is described as a Wiener-Levy stochastic process modified by two correlation lengths in such a way that H-p is stationary for large DW displacements and dH(p) /dx(DW) is well defined for small DW displacements. The computed H-CW(G) is close to a hyperbolic decrease, but it approaches finite values if G-->O and it decreases in a much steeper way than alpha 1/G for high values of G, which agrees with the experimental observations. Experimentally, the dependence H-CW(G) was measured on close-packed arrays of cylindrical bubble domains in two thin films of magnetic garnets, where the local field gradient, G, was controlled within the range 10(9)-10(10) A/m(2) by changing distances between neighboring DW's. The DW coercive field, H-CW, extrapolated from the measured values for G-->O was close to 80 A/m for both samples, while H-CW(G approximate to 10(10) A/m(2)) was several times smaller. Fitting the calculated H-CW(G) dependence to the experimental data, we obtained values of the Wiener-Levy correlation lengths well comparable to the DW width parameters
First results with the boloSource() algorithm: Photometry of faint standard stars observed by Herschel/PACS
The boloSource() algorithm is a tool to separate the signal of compact
sources from that of the diffuse background in the timeline of far-infrared
measurements performed by the PACS camera of the Herschel Space Observatory. An
important characteristic and quality indicator of this method is that how well
it can reproduce the flux of faint standard stars which have reliable flux
estimates. For this propose we selected a few calibrator targets and
constructed light curves by extracting point source flux for each repetition of
the measurements independently using standard aperture photometry methods.
These were compared with the light curves obtained using the boloSource()
method on the same dataset. The results indicate that boloSource() provides a
similar level of photometric accuracy and reproducibility as the usual flux
extraction and photometry methods. This new technique will be developed further
and also tested against other methods in more complex fields with the goal to
make it usable for large-scale studies in the future.Comment: 10 pages, 7 figures, 4 table
Rovibronic spectra of molecules dressed by light fields
The theory of rovibronic spectroscopy of light-dressed molecules is presented
within the framework of quantum mechanically treated molecules interacting with
classical light fields. Numerical applications are demonstrated for the
homonuclear diatomic molecule Na, for which the general formulae can be
simplified considerably and the physical processes leading to the light-dressed
spectra can be understood straightforwardly. The physical origin of different
peaks in the light-dressed spectrum of Na is given and the light-dressed
spectrum is investigated in terms of its dependence on the dressing field's
intensity and wavelength, the turn-on time of the dressing field, and the
temperature. The important implications of light-dressed spectroscopy on
deriving field-free spectroscopic quantities are also discussed
Contractual relationships in the Hungarian milk sector
In this paper we present an empirical analysis of farmers' contracting choice in the Hungarian milk sector using 2005 milk producer survey data, employing transaction cost economics. We focus on analysing some key determinants of farmers' contracting choices: type of contracts, duration, number of contractors, incentives provided in the contract and business history of farmers and buyers. Some of the main results include the importance and effect of farm size, quantity of milk delivered, planned short and long run or contract related investment on farm, the possibility of farmer to influence prices on the contracting choices. --transaction costs,contracts,milk products,Hungary
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