Critical Current Peaks at 3BΦ3B_{\Phi} in Superconductors with Columnar Defects: Recrystalizing the Interstitial Glass

The role of commensurability and the interplay of correlated disorder and interactions on vortex dynamics in the presence of columnar pins is studied via molecular dynamics simulations. Simulations of dynamics reveal substantial caging effects and a non-monotonic dependence of the critical current with enhancements near integer values of the matching field $B_{\phi}$ and $3B_{\phi}$ in agreement with experiments on the cuprates. We find qualitative differences in the phase diagram for small and large values of the matching field.Comment: 5 pages, 4 figures (3 color

Cholinergic suppression: A postsynaptic mechanism of long-term associative learning

Food avoidance learning in the mollusc Pleurobranchaea entails reduction in the responsiveness of key brain interneurons in the feeding neural circuitry, the paracerebral feeding command interneurons (PCNs), to the neurotransmitter acetylcholine (AcCho). Food stimuli applied to the oral veil of an untrained animal depolarize the PCNs and induce the feeding motor program (FMP). Atropine (a muscarinic cholinergic antagonist) reversibly blocks the food-induced depolarization of the PCNs, implicating AcCho as the neurotransmitter mediating food detection. AcCho applied directly to PCN somata depolarizes them, indicating that the PCN soma membrane contains AcCho receptors and induces the FMP in the isolated central nervous system preparation. The AcCho response of the PCNs is mediated by muscariniclike receptors, since comparable depolarization is induced by muscarinic agonists (acetyl-ß -methylcholine, oxotremorine, pilocarpine), but not nicotine, and blocked by muscarinic antagonists (atropine, trifluoperazine). The nicotinic antagonist hexamethonium, however, blocked the AcCho response in four of six cases. When specimens are trained to suppress feeding behavior using a conventional food-avoidance learning paradigm (conditionally paired food and shock), AcCho applied to PCNs in the same concentration as in untrained animals causes little or no depolarization and does not initiate the FMP. Increasing the concentration of AcCho 10-100 times, however, induces weak PCN depolarization in trained specimens, indicating that learning diminishes but does not fully abolish AcCho responsiveness of the PCNs. This study proposes a cellular mechanism of long-term associative learning -- namely, postsynaptic modulation of neurotransmitter responsiveness in central neurons that could apply also to mammalian species

Jurisdictional Roadside Ditches

Section 404 of the Clean Water Act (CWA) mandates that state agencies and other entities perform compensatory mitigation when their activities impair jurisdictional waters. In the Commonwealth of Kentucky, the Kentucky Transportation Cabinet (KYTC) is required to pay in-lieu fees or purchase stream mitigation credits when a roadside ditch is impaired or relocated as part of a road construction project. In-lieu fees and stream mitigation credits are costly, and ditches that have suffered degraded habitat and loss of hydrogeomorphic functionality are treated as total losses when they are impacted by construction and maintenance activities. This raises the question of whether the United States Corps of Engineers (USACE) would be receptive to alternative mitigation and monitoring practices that impose a less stringent financial burden on the Kentucky Transportation Cabinet, but which still comply with CWA regulations. This report discusses methodologies used to evaluate the quality of instream and riparian habitat, Section 404 of the CWA and its implications for mitigation of lost or damaged jurisdictional ditches, and the strategies that have been used by other states to fulfill their Section 404 mitigation requirements. We highlight mitigation practices that depart from the norm and which place a less onerous financial burden on state transportation agencies. KYTC officials presented this report’s key findings to the USACE Louisville District Office in January 2015 in an effort to receive approval to experiment with novel restoration techniques. The USACE granted KYTC license to implement these techniques on a project-by- project basis. Before implementation on each project, the Cabinet must receive formal approval from USACE officials. Although this was not the blanket mandate that KYTC hoped for, it indicated the Louisville District is willing to study the effectiveness of alternative mitigation strategies. Despite the Cabinet’s request, USACE officials did not approve a plan to reduce post-restoration monitoring requirements. KTC researchers suggested that KYTC perform exhaustive monitoring of the performance of completed project that used alternative mitigation techniques. Having information on the short-, medium-, and long-term performance of these sites could–if the results are promising-pave the way to the wider adoption of alternative mitigation practices and could eventually reduce the level of post-restoration monitoring required by the USACE

Line Intensities and Molecular Opacities of the FeH F4Δi−X4ΔiF^4\Delta_i-X^4\Delta_i Transition

We calculate new line lists and opacities for the $F^4\Delta_i-X^4\Delta_i$ transition of FeH. The 0-0 band of this transition is responsible for the Wing-Ford band seen in M-type stars, sunspots and brown dwarfs. The new Einstein A values for each line are based on a high level ab initio calculation of the electronic transition dipole moment. The necessary rotational line strength factors (H\"onl-London factors) are derived for both the Hund's case (a) and (b) coupling limits. A new set of spectroscopic constants were derived from the existing FeH term values for v=0, 1 and 2 levels of the $X$ and $F$ states. Using these constants extrapolated term values were generated for v=3 and 4 and for $J$ values up to 50.5. The line lists (including Einstein A values) for the 25 vibrational bands with v$\leq$4 were generated using a merged list of experimental and extrapolated term values. The FeH line lists were use to compute the molecular opacities for a range of temperatures and pressures encountered in L and M dwarf atmospheres. Good agreement was found between the computed and observed spectral energy distribution of the L5 dwarf 2MASS-1507.Comment: 52 pages, 3 figures, many tables, accepted for publication in the Astrophysical Journal Supplement

Observations of the high vibrational levels of the B′′B̄ 1Σu+ state of H2

Double-resonance laser spectroscopy via the E F 1Σg+, v\u27=6, J\u27=0-2 state was used to probe the high vibrational levels of the B B-bar 1Σu+ state of molecular hydrogen. Resonantly-enhanced multiphoton ionization spectra were recorded by detecting ion production as a function of energy using a time of flight mass spectrometer. New measurements of energies for the v=51-66 levels for the B B-bar state of H2 are reported, which, taken with previous results, span the v=46-69 vibrational levels. Results for energy levels are compared to theoretical close-coupled calculations [L. Wolniewicz, T. Orlikowski, and G. Staszewska, J. Mol. Spec. 238, 118 (2006)]. The average difference between the 84 measured energies and calculated energies is -3.8 cm-1 with a standard deviation of 5.3 cm-1. This level of agreement showcases the success of the theoretical calculations in accounting for the strong rovibronic mixing of the 1Σu+ and 1Πu+ states. Due to the ion-pair character of the outer well, the observed energies of the vibrational levels below the third dissociation limit smoothly connect with previously observed energies of ion-pair states above this limit. The results provide an opportunity for testing a heavy Rydberg multi-channel quantum defect analysis of the high vibrational states below the third dissociation limit

Observations of the high vibrational levels of the B′′B̄ 1Σu+ state of H2

Double-resonance laser spectroscopy via the E F 1Σg+, v\u27=6, J\u27=0-2 state was used to probe the high vibrational levels of the B B-bar 1Σu+ state of molecular hydrogen. Resonantly-enhanced multiphoton ionization spectra were recorded by detecting ion production as a function of energy using a time of flight mass spectrometer. New measurements of energies for the v=51-66 levels for the B B-bar state of H2 are reported, which, taken with previous results, span the v=46-69 vibrational levels. Results for energy levels are compared to theoretical close-coupled calculations [L. Wolniewicz, T. Orlikowski, and G. Staszewska, J. Mol. Spec. 238, 118 (2006)]. The average difference between the 84 measured energies and calculated energies is -3.8 cm-1 with a standard deviation of 5.3 cm-1. This level of agreement showcases the success of the theoretical calculations in accounting for the strong rovibronic mixing of the 1Σu+ and 1Πu+ states. Due to the ion-pair character of the outer well, the observed energies of the vibrational levels below the third dissociation limit smoothly connect with previously observed energies of ion-pair states above this limit. The results provide an opportunity for testing a heavy Rydberg multi-channel quantum defect analysis of the high vibrational states below the third dissociation limit

Observations of the high vibrational levels of the B′′B̄ 1Σ+u state of H2

Double-resonance laser spectroscopy via the E F 1Σ+g, v\u27 = 6, J\u27 = 0–2 state was used to probe the high vibrational levels of the B′′B̄ 1Σ+u state of molecular hydrogen. Resonantly enhanced multiphotonionization spectra were recorded by detecting ion production as a function of energy using a time of flight mass spectrometer. New measurements of energies for the v = 51–66 levels for the B00B ̄ state of H2 are reported, which, taken with previous results, span the v = 46–69 vibrational levels. Results for energy levels are compared to theoretical close-coupled calculations [L. Wolniewicz, T. Orlikowski, and G. Staszewska, J. Mol. Spectrosc. 238, 118–126 (2006)]. The average difference between the 84 measured energies and calculated energies is 3.8 cm–1 with a standard deviation of 5.3 cm–1. This level of agreement showcases the success of the theoretical calculations in accounting for the strong rovibronic mixing of the 1Σu+ and 1Πu+ states. Due to the ion-pair character of the outer well, the observed energies of the vibrational levels below the third dissociation limit smoothly connect with previously observed energies of ion-pair states above this limit. The results provide an opportunity for testing a heavy Rydberg multi-channel quantum defect analysis of the high vibrational states below the third dissociation limit