The confined-deconfined interface tension, wetting, and the spectrum of the transfer matrix

The reduced tension $\sigma_{cd}$ of the interface between the confined and the deconfined phase of $SU(3)$ pure gauge theory is determined from numerical simulations of the first transfer matrix eigenvalues. At $T_c = 1/L_t$ we find $\sigma_{cd} = 0.139(4) T_c^2$ for $L_t = 2$. The interfaces show universal behavior because the deconfined-deconfined interfaces are completely wet by the confined phase. The critical exponents of complete wetting follow from the analytic interface solutions of a $\Z(3)$-symmetric $\Phi^4$ model in three dimensions. We find numerical evidence that the confined-deconfined interface is rough.Comment: Talk presented at the International Conference on Lattice Field Theory, Lattice 92, to be published in the proceedings, 4 pages, 4 figures, figures 2,3,4 appended as postscript files, figure 1 not available as a postscript file but identical with figure 2 of Nucl. Phys. B372 (1992) 703, special style file espcrc2.sty required (available from hep-lat), BUTP-92/4

A Multicanonical Algorithm and the Surface Free Energy in SU(3) Pure Gauge Theory

We present a multicanonical algorithm for the SU(3) pure gauge theory at the deconfinement phase transition. We measure the tunneling times for lattices of size L^3x2 for L=8,10, and 12. In contrast to the canonical algorithm the tunneling time increases only moderately with L. Finally, we determine the interfacial free energy applying the multicanonical algorithm.Comment: 6 pages, HLRZ-92-3

The Interface Tension in Quenched QCD at the Critical Temperature

We present results for the confinement-deconfinement interface tension $\alpha_{cd}$ of quenched QCD. They were obtained by applying Binder's histogram method to lattices of size $L^2\times L_z\times L_t$ for $L_t=2$ and L=8,10,12\mbox{ and }14 with $L_z=30$ for $L=8$ and $L_z=3L$ otherwise. The use of a multicanonical algorithm and cylindrical geometries have turned out to be crucial for the numerical studies.Comment: (talk presented by B. Grossmann at Lattice 92), 4 pages with 5 figure appended as encapsulated postscript files at the end, preprint HLRZ-92-7

Relating Molecular Morphology to Charge Mobility in Semicrystalline Conjugated Polymers

The molecular-level origins of the effects of annealing temperature and molecular weight on hole mobility in P3HT are elucidated using coarse-grained molecular dynamics, quantum chemical calculations, and kinetic Monte Carlo charge-transport simulations on a variety of realistic thin-film morphologies. The zero-field hole mobility is shown to increase as the annealing temperature or average molecular weights of samples are increased, in accordance with experimental results. Crystal structure analysis shows that the annealing temperature dependence of the mobility can be attributed to the size and structural order of the crystallites in both the chain-backbone and π-stacking directions. However, the molecular weight dependence of the mobility cannot be rationalized in the same way. Longer chains are shown to belong to more crystallites in the morphology, suggesting that the crystals become better connected as the molecular weight of the sample increases. We show that engineering samples to have an increased fraction of these long “tie chains” within the morphology improves mobility. As such, we propose that crystal connectivity in the noncrystalline portions of the morphology is similarly important in determining carrier mobility as crystallite size and order for semicrystalline conjugated polymers

Charge fluctuations and electron-phonon interaction in the finite-UU Hubbard model

In this paper we employ a gaussian expansion within the finite-$U$ slave-bosons formalism to investigate the momentum structure of the electron-phonon vertex function in the Hubbard model as function of $U$ and $n$. The suppression of large momentum scattering and the onset a small-${\bf q}$ peak structure, parametrized by a cut-off $q_c$, are shown to be essentially ruled by the band narrowing factor $Z_{\rm MF}$ due to the electronic correlation. A phase diagram of $Z_{\rm MF}$ and $q_c$ in the whole $U$-$n$ space is presented. Our results are in more than qualitative agreement with a recent numerical analysis and permit to understand some anomalous features of the Quantum Monte Carlo data.Comment: 4 pages, eps figures include

OmOm Diagnostic for Dilaton Dark Energy

$Om$ diagnostic can differentiate between different models of dark energy without the accurate current value of matter density. We apply this geometric diagnostic to dilaton dark energy(DDE) model and differentiate DDE model from LCDM. We also investigate the influence of coupled parameter $\alpha$ on the evolutive behavior of $Om$ with respect to redshift $z$. According to the numerical result of $Om$, we get the current value of equation of state $\omega_{\sigma0}$=-0.952 which fits the WMAP5+BAO+SN very well.Comment: 6 pages and 6 figures

Proteorhodopsin overproduction enhances the long-term viability of Escherichia coli

Genes encoding the photoreactive protein proteorhodopsin (PR) have been found in a wide range of marine bacterial species, reflecting the significant contribution that PR makes to energy flux and carbon cycling in ocean ecosystems. PR can also confer advantages to enhance the ability of marine bacteria to survive periods of starvation. Here, we investigate the effect of heterologously produced PR on the viability of Escherichia coli. Quantitative mass spectrometry shows that E. coli, exogenously supplied with the retinal cofactor, assembles as many as 187,000 holo-PR molecules per cell, accounting for approximately 47% of the membrane area; even cells with no retinal synthesize ∼148,000 apo-PR molecules per cell. We show that populations of E. coli cells containing PR exhibit significantly extended viability over many weeks, and we use single-cell Raman spectroscopy (SCRS) to detect holo-PR in 9-month-old cells. SCRS shows that such cells, even incubated in the dark and therefore with inactive PR, maintain cellular levels of DNA and RNA and avoid deterioration of the cytoplasmic membrane, a likely basis for extended viability. The substantial proportion of the E. coli membrane required to accommodate high levels of PR likely fosters extensive intermolecular contacts, suggested to physically stabilize the cell membrane and impart a long-term benefit manifested as extended viability in the dark. We propose that marine bacteria could benefit similarly from a high PR content, with a stabilized cell membrane extending survival when those bacteria experience periods of severe nutrient or light limitation in the oceans

A low-voltage retarding-field Mott polarimeter for photocathode characterization

Nuclear physics experiments at Thomas Jefferson National Accelerator Facility's CEBAF rely on high polarization electron beams. We describe a recently commissioned system for prequalifying and studying photocathodes for CEBAF with a load-locked, low-voltage polarized electron source coupled to a compact retarding-field Mott polarimeter. The polarimeter uses simplified electrode structures and operates from 5 to 30 kV. The effective Sherman function for this device has been calibrated by comparison with the CEBAF 5 MeV Mott polarimeter. For elastic scattering from a thick gold target at 20 keV, the effective Sherman function is 0.201(5). Its maximum efficiency at 20 keV, defined as the detected count rate divided by the incident particle current, is 5.4(2) x 10-4, yielding a figure-of-merit, or analyzing power squared times efficiency, of 1.0(1) x 10-5. The operating parameters of this new polarimeter design are compared to previously published data for other compact Mott polarimeters of the retarding-field type.Comment: 9 figure

Time-dependent linear response of an inhomogeneous Bose superfluid: Microscopic theory and connection to current-density functional theory

The dynamics of a confined fluid of Bose atoms is treated within the linear response regime, with a view to establishing a current-density functional formalism for an inhomogeneous superfluid state. After evaluating in full detail a simplified case of an external coupling to the density and phase of the condensate, the theory is extended to include the coupling to the total current density. The Kohn-Sham response functions of the condensate and all the exchange-correlation kernels for the superfluid are introduced from the microscopic equations of motion and are expressed in a physically transparent way through functional derivatives of correlation functions. A microscopic formula for the superfluid density is derived and used to introduce a generalized hydrodynamic approach for a weakly inhomogeneous two-fluid model in isothermal conditions. Local-density expressions are thereby derived for the velocities of first and second sound in the weakly inhomogeneous superfluid and for visco-elastic functions describing the transition from the hydrodynamic to the collisionless regime. Landau's hydrodynamic theory and known results in Green's functions language are recovered in the limiting case of a homogeneous superfluid.Comment: 25 pages, no figures, Postscript fil