Collective effects in charge transfer within a hybrid organic-inorganic system

A collective electron transfer (ET) process was discovered by studying the current noise in a field effect transistor with light-sensitive gate formed by nanocrystals linked by organic molecules to its surface. Fluctuations in the ET through the organic linker are reflected in the fluctuations of the transistor conductivity. The current noise has an avalanche character. Critical exponents obtained from the noise power spectra, avalanche distributions, and the dependence of the average avalanche size on avalanche duration are consistent with each other. A plausible model is proposed for this phenomenonComment: 15 pages 4 figures. Accepted for publication in Physical Review Letter

Rab8a and Rab8b are essential for several apical transport pathways but insufficient for ciliogenesis

The small GTP-binding protein Rab8 is known to play an essential role in intracellular transport and cilia formation. We have previously demonstrated that Rab8a is required for localising apical markers in various organisms. Rab8a has a closely related isoform, Rab8b. To determine whether Rab8b can compensate for Rab8a, we generated Rab8b-knockout mice. Although the Rab8b-knockout mice did not display an overt phenotype, Rab8a and Rab8b double-knockout mice exhibited mislocalisation of apical markers and died earlier than Rab8a-knockout mice. The apical markers accumulated in three intracellular patterns in the double-knockout mice. However, the localisation of basolateral and/or dendritic markers of the double-knockout mice seemed normal. The morphology and the length of various primary and/or motile cilia, and the frequency of ciliated cells appeared to be identical in control and double-knockout mice. However, an additional knockdown of Rab10 in double-knockout cells greatly reduced the percentage of ciliated cells. Our results highlight the compensatory effect of Rab8a and Rab8b in apical transport, and the complexity of the apical transport process. In addition, neither Rab8a nor Rab8b are required for basolateral and/or dendritic transport. However, simultaneous loss of Rab8a and Rab8b has little effect on ciliogenesis, whereas additional loss of Rab10 greatly affects ciliogenesis

1/f spectrum and memory function analysis of solvation dynamics in a room-temperature ionic liquid

To understand the non-exponential relaxation associated with solvation dynamics in the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate, we study power spectra of the fluctuating Franck-Condon energy gap of a diatomic probe solute via molecular dynamics simulations. Results show 1/f dependence in a wide frequency range over 2 to 3 decades, indicating distributed relaxation times. We analyze the memory function and solvation time in the framework of the generalized Langevin equation using a simple model description for the power spectrum. It is found that the crossover frequency toward the white noise plateau is directly related to the time scale for the memory function and thus the solvation time. Specifically, the low crossover frequency observed in the ionic liquid leads to a slowly-decaying tail in its memory function and long solvation time. By contrast, acetonitrile characterized by a high crossover frequency and (near) absence of 1/f behavior in its power spectra shows fast relaxation of the memory function and single-exponential decay of solvation dynamics in the long-time regime.Comment: 10 pages, 4 figure

TMDlib and TMDplotter: library and plotting tools for transverse-momentum-dependent parton distributions

Transverse-momentum-dependent distributions (TMDs) are central in high-energy physics from both theoretical and phenomenological points of view. In this manual we introduce the library, TMDlib, of fits and parameterisations for transverse-momentum-dependent parton distribution functions (TMD PDFs) and fragmentation functions (TMD FFs) together with an online plotting tool, TMDplotter. We provide a description of the program components and of the different physical frameworks the user can access via the available parameterisations.Comment: version 2, referring to TMDlib 1.0.2 - comments and references adde

Taste symmetry breaking with HYP-smeared staggered fermions

We study the impact of hypercubic (HYP) smearing on the size of taste breaking for staggered fermions, comparing to unimproved and to asqtad-improved staggered fermions. As in previous studies, we find a substantial reduction in taste-breaking compared to unimproved staggered fermions (by a factor of 4-7 on lattices with spacing $a\approx 0.1$fm). In addition, we observe that discretization effects of next-to-leading order in the chiral expansion (${\cal O}(a^2 p^2)$) are markedly reduced by HYP smearing. Compared to asqtad valence fermions, we find that taste-breaking in the pion spectrum is reduced by a factor of 2.5-3, down to a level comparable to the expected size of generic ${\cal O}(a^2)$ effects. Our results suggest that, once one reaches a lattice spacing of $a\approx 0.09$fm, taste-breaking will be small enough after HYP smearing that one can use a modified power counting in which ${\cal O}(a^2) \ll {\cal O}(p^2)$, simplify fitting to phenomenologically interesting quantities.Comment: 14 pages, 13 figures, references updated, minor change

Spectroscopic Evidence for Anisotropic S-Wave Pairing Symmetry in MgB2

Scanning tunneling spectroscopy of superconducting MgB$_2$ ($T_c = 39$ K) were studied on high-density pellets and c-axis oriented films. The sample surfaces were chemically etched to remove surface carbonates and hydroxides, and the data were compared with calculated spectra for all symmetry-allowed pairing channels. The pairing potential ($\Delta_k$) is best described by an anisotropic s-wave pairing model, with $\Delta_k = \Delta_{xy} \sin ^2 \theta_k + \Delta_z \cos ^2 \theta_k$, where $\theta_k$ is the angle relative to the crystalline c-axis, $\Delta_z \sim 8.0$ meV, and $\Delta_{xy} \sim 5.0$ meV.Comment: 4 pages and 3 figures. Submitted to Physical Review Letters. Corresponding author: Nai-Chang Yeh (e-mail: [email protected]