Shift Equivalence of Measures and the Intrinsic Structure of Shocks in the Asymmetric Simple Exclusion Process

We investigate the properties of non-translation-invariant measures, describing particle systems on $\mathbb{Z}$ , which are asymptotic to different translation invariant measures on the left and on the right. Often the structure of the transition region can only be observed from a point of view which is random—in particular, configuration dependent. Two such measures will be called shift equivalent if they differ only by the choice of such a viewpoint. We introduce certain quantities, called translation sums, which, under some auxiliary conditions, characterize the equivalence classes. Our prime example is the asymmetric simple exclusion process, for which the measures in question describe the microscopic structure of shocks. In this case we compute explicitly the translation sums and find that shocks generated in different ways—in particular, via initial conditions in an infinite system or by boundary conditions in a finite system—are described by shift equivalent measures. We show also that when the shock in the infinite system is observed from the location of a second class particle, treating this particle either as a first class particle or as an empty site leads to shift equivalent shock measures.     

Free energy functional for nonequilibrium systems: an exactly solvable case

We consider the steady state of an open system in which there is a flux of matter between two reservoirs at different chemical potentials. For a large system of size N, the probability of any macroscopic density profile rho(x) is exp[-NF([rho])]; F thus generalizes to nonequilibrium systems the notion of free energy density for equilibrium systems. Our exact expression for F is a nonlocal functional of rho, which yields the macroscopically long range correlations in the nonequilibrium steady state previously predicted by fluctuating hydrodynamics and observed experimentally.     

Pairing effects in nucleon transfer reactions in the system144Sm+88Sr at 4.7 MeV/u

Proton and neutron transfer populating low-lying states have been studied in the system¹⁴⁴Sm+⁸⁸Sr at an energy below the Coulomb barrier. The experimental cross sections for the single proton transfer are well reproduced by DWBA-calculations using spectroscopic information from light ion reactions. The two-proton transfer appears enhanced relative to the uncorrelated sequential transfer of single protons. The same holds for the transfer of proton pairs, the enhancement is kept for the second pair. This is interpreted as a supercurrent between two superfluid nuclear proton-pair wave functions: more mass and charge is transported per time unit in pairs than by single nucleons. Neutron transfer is observed with large cross sections and is found to contribute to the energy loss observed in the transfer reactions. For mixed proton-neutron transfers the sequential nature of the transfer reactions is established in a similar way as for the two-proton and two-neutron transfer; in the latter case no enhancement is observed.     

Assessment of sample cleanup and matrix effects in the pesticide residue analysis of foods using postcolumn infusion in liquid chromatography-tandem mass spectrometry

Matrix effect profiles can be used to visualize the effect of the sample matrix to the data signals occurring in a chromatogram. In the present study these profiles were generated by postcolumn infusion of a standard pesticide mix with extracts of different food matrices prepared by the QuEChERS method. Complete raw extracts as well as individual clean-up steps were analyzed. This allowed for a detailed comparison of the interferences caused by the matrix effects from various food samples. It also gave an idea about the efficiency of matrix reduction processes. When analyzing the individual clean-up extracts of the QuEChERS method just a slight reduction of matrix effects could be observed from step to step. Matrices causing strong signal effects in the results of the raw extracts also have strong effects after the final clean-up step. Some of the components responsible for the matrix effects show an extremely high retention time. After the injection of extracts from rocket or different types of tea, significant ion suppressions occurred even after rinsing the analytical column for a long time. The experiments have shown that similar matrices can produce different matrix effect profiles. For example, for black teas and green teas significantly different matrix effect profiles were obtained, while the matrix effects of teas within one of these groups were exactly the same. Analogous results could be found for citrus fruits. In order to overcome interfering matrix effects, analytical systems equipped with different electrospray ion sources were tested. Furthermore, profiles of diluted food extracts were generated. Dilution led to a significant decrease in the matrix effects.     

Failure of reflection positivity in the quantum Heisenberg ferromagnet

We show that reflection positivity does not hold in the finite-volume spin 1/2 quantum Heisenberg ferromagnet in two cases: (i) for any dimension or degree ofS ¹-invariant anisotropy, above a volume independent temperatureT ₀, and (ii) for the isotropic model in one dimension, below a volume dependent temperatureT ₁.