On the Two Species Asymmetric Exclusion Process with Semi-Permeable Boundaries

We investigate the structure of the nonequilibrium stationary state (NESS) of a system of first and second class particles, as well as vacancies (holes), on L sites of a one-dimensional lattice in contact with first class particle reservoirs at the boundary sites; these particles can enter at site 1, when it is vacant, with rate α, and exit from site L with rate β. Second class particles can neither enter nor leave the system, so the boundaries are semi-permeable. The internal dynamics are described by the usual totally asymmetric exclusion process (TASEP) with second class particles. An exact solution of the NESS was found by Arita. Here we describe two consequences of the fact that the flux of second class particles is zero. First, there exist (pinned and unpinned) fat shocks which determine the general structure of the phase diagram and of the local measures; the latter describe the microscopic structure of the system at different macroscopic points (in the limit L→∞) in terms of superpositions of extremal measures of the infinite system. Second, the distribution of second class particles is given by an equilibrium ensemble in fixed volume, or equivalently but more simply by a pressure ensemble, in which the pair potential between neighboring particles grows logarithmically with distance. We also point out an unexpected feature in the microscopic structure of the NESS for finite L: if there are n second class particles in the system then the distribution of first class particles (respectively holes) on the first (respectively last) n sites is exchangeable.     

Holographic dark energy interacting with dark matter in a closed Universe

A cosmological model of an holographic dark energy interacting with dark matter throughout a decaying term of the form Q=3(λ₁ρDE+λ₂ρm)H$Q=3({\lambda }_1{\rho }_{\mathrm{DE}}+{\lambda }_2{\rho }_m)H$ is investigated. General constraint on the parameters of the model are found when accelerated expansion is imposed and we found a phantom scenario, without any reference to a specific equation of state for the dark energy. The behavior of equation of state for dark energy is also discussed.     

Synthesis of resonant cavities having continuum spectra by genetic algorithm

This paper proposes a novel method for generating continuum spectra with possible applications in WDM access networks. This new method would allow the development of a simple continuum laser structure with better performances in terms of cost and simplicity than those of present supercontinuum sources. In this aim, we will analyze the possibility to broaden the resonant modes of a Fabry–Perot cavity by operating only on the design of one of the cavity's Bragg mirrors. Firstly we considered the conditions which a Bragg grating must satisfy in order to broaden the resonant modes of a resonant cavity. Because an exact solution is not physical possible, the genetic algorithm is the best available tool for the design of such a grating. An active medium is then added inside the cavity and its behavior below threshold is simulated. The spectra thus simulated are continuum over 5–15 nm.     

X-Ray Spectra of Iron Phosphonates

The reaction of dialkyl alkylphosphonates with trivalent metal chlorides has recently been reported (1,2). The typical products of these reactions is a solid which is insoluble in most organic solvents and water. A monomeric structure was postulated for the iron phosphonates(1), while polynuclear structure was proposed for titanium, vanadium, and chromium phosphonates(2). Infrared(1) and Mossbauer-effect(3) studies were unable to differentiate between the monomeric or polynuclear structure for the iron phosphonates, In an attempt to further characterize the iron phosphonates, an x-ray diffration study was undertaken. The results of these studies are reported herein.     

NMR Studies of Drugs. Methaqualone. Approaches to Rigorous 1H and 13C Assignments with Applications of Achiral and Chiral Shift Reagents

The ¹H and ¹³C NMR spectra of methaqualone, 1, have been extensively studied using one and two-dimensional techniques. These 300 MHz ¹H and 75 MHz ¹³C studies have allowed rigorous assignments to be made for the methyl groups and the quinazolinone nucleus. The 60 MHz ¹H spectra for 1 in CDCl₃ have been examined with     

Existence,uniqueness, and nondegeneracy of positive solutions of semilinear elliptic equations

We study positive solutions of the Dirichlet problem: u(x)+f(u(x))=0,xD ⁿ ,u(x)=0,xD ⁿ , whereD ⁿ is ann-ball. We find necessary and sufficient conditions for solutions to be nondegenerate. We also give some new existence and uniqueness theorems.Research supported in part by NSF Contract Number MCS 80-02337     

The effect of disordering on the spectral properties of partial monolayers of H on Si(111)

Ultraviolet photoemission measurements are reported for a H covered Si(111) surface for which the H coverage ranged from a fraction to a full monolayer. These measurements reveal striking differences depending whether the Si(111) substrate is kept at room temperature (RT) or 150°C. In particular, the 150°C sample UPS spectral series shows monotonic growth with little line shape change while the RT series shows significant line shape modification with coverage. These results are interpreted as island growth at 150°C and disordered adsorption at RT. Theoretical model calculations are carried out of the electron density of states of a fractional monolayer of H chemisorbed to Si(111) that reproduce the essential features of the RT data and confirm the role of disordering there.     

An observation on the effect of fluctuations far from equilibrium: The Lotka-Volterra model

Spontaneous fluctuations in the Lotka-Volterra model of chemical reactions are known to grow in an unbounded way when species held in excess are neglected. This result is obtained in a simple way using generalized fluctuation-dissipation principles but appears to be an artifact of ignoring fluctuations in the variables that are held fixed. When fluctuations in the other concentrations are included in the model, the spontaneous fluctuations become bounded.This work was supported by the National Science Foundation through Research Grant No. MPS 74-00483 AO1.     

Percolation in strongly correlated systems: The massless Gaussian field

We derive a number of new results for correlated nearest neighbor site percolation onZ ^d. We show in particular that in three dimensions the strongly correlated massless harmonic crystal, i.e., the Gaussian random field with mean zero and covariance –, has a nontrivial percolation behavior: sites on whichS _x h percolate if and only ifh _c . with0 _c < . This provides the first rigorous example of a percolation transition in a system with infinite susceptibility.