Quantum Reciprocity Conjecture for the Non-Equilibrium Steady State

By considering the lack of history dependence in the non-equilibrium steady state of a quantum system we are led to conjecture that in such a system, there is a set of quantum mechanical observables whose retarded response functions are insensitive to the arrow of time, and which consequently satisfy a quantum analog of the Onsager reciprocity relations. Systems which satisfy this conjecture can be described by an effective Free energy functional. We demonstrate that the conjecture holds in a resonant level model of a multi-lead quantum dot.Comment: References revised to take account of related work on Onsager reciprocity in mesoscopics by Christen, and in hydrodynamics by Mclennan, Dufty and Rub

Lattice dynamics and electron-phonon coupling in Sr2RuO4

The lattice dynamics in Sr$_2$RuO$_4$ has been studied by inelastic neutron scattering combined with shell-model calculations. The in-plane bond-stretching modes in Sr$_2$RuO$_4$ exhibit a normal dispersion in contrast to all electronically doped perovskites studied so far. Evidence for strong electron phonon coupling is found for c-polarized phonons suggesting a close connection with the anomalous c-axis charge transport in Sr$_2$RuO$_4$.Comment: 11 pages, 8 figures 2 table

A two-step approach for calculating chloride diffusion coefficient in concrete with both natural and recycled concrete aggregates.

This paper presents an analytical approach to calculate the effective diffusion coefficient of chlorides in concrete with both natural and recycled concrete aggregates. In the approach the concrete is treated as a composite consisting of three phases, namely mortar, natural aggregate plus interfacial transition zone, and recycled concrete aggregate plus interfacial transition zone. The effective diffusion coefficient of chlorides in the composite is calculated through two steps. The first step is to calculate the effective diffusion coefficients of chlorides in the natural aggregate plus interfacial transition zone and in the recycled concrete aggregate plus interfacial transition zone by using multilayer spherical approximation, the results of which provide the information about the quality of recycled concrete aggregate in terms of chloride penetration resistance. The second step is to calculate the effective diffusion coefficient of chlorides in the three-phase concrete composite by using effective medium approximation, the results of which provide the information about the influence of recycled concrete aggregate on the diffusivity of recycled aggregate concrete. The analytical expression of the effective diffusion coefficient is derived and carefully compared with the results obtained from both the experiments and numerical simulations, which demonstrates that the present analytical model is rational and reliable. The analytical expression presented can be used to predict the service life of recycled aggregate concrete exposed to chloride environment

Statistical analysis on spatial correlation of ionospheric day-to-day variability by using GPS and Incoherent Scatter Radar observations

In this paper, the spatial correlations of ionospheric day-to-day variability are investigated by statistical analysis on GPS and Incoherent Scatter Radar observations. The meridional correlations show significant (>0.8) correlations in the latitudinal blocks of about 6 degrees size on average. Relative larger correlations of TEC's day-to-day variabilities can be found between magnetic conjugate points, which may be due to the geomagnetic conjugacy of several factors for the ionospheric day-to-day variability. The correlation coefficients between geomagnetic conjugate points have an obvious decrease around the sunrise and sunset time at the upper latitude (60°) and their values are bigger between the winter and summer hemisphere than between the spring and autumn hemisphere. The time delay of sunrise (sunset) between magnetic conjugate points with a high dip latitude is a probable reason. Obvious latitude and local time variations of meridional correlation distance, latitude variations of zonal correlation distance, and altitude and local time variations of vertical correlation distance are detected. Furthermore, there are evident seasonal variations of meridional correlation distance at higher latitudes in the Northern Hemisphere and local time variations of zonal correlation distance at higher latitudes in the Southern Hemisphere. These variations can generally be interpreted by the variations of controlling factors, which may have different spatial scales. The influences of the occurrence of ionospheric storms could not be ignored. Further modeling and data analysis are needed to address this problem. We suggest that our results are useful in the specific modeling/forecasting of ionospheric variability and the constructing of a background covariance matrix in ionospheric data assimilation

Emergence of intrinsic superconductivity below 1.178 K in the topologically non-trivial semimetal state of CaSn3

Topological materials which are also superconducting are of great current interest, since they may exhibit a non-trivial topologically-mediated superconducting phase. Although there have been many reports of pressure-tuned or chemical-doping-induced superconductivity in a variety of topological materials, there have been few examples of intrinsic, ambient pressure superconductivity in a topological system having a stoichiometric composition. Here, we report that the pure intermetallic CaSn3 not only exhibits topological fermion properties but also has a superconducting phase at 1.178 K under ambient pressure. The topological fermion properties, including the nearly zero quasi-particle mass and the non-trivial Berry phase accumulated in cyclotron motions, were revealed from the de Haas-van Alphen (dHvA) quantum oscillation studies of this material. Although CaSn3 was previously reported to be superconducting at 4.2K, our studies show that the superconductivity at 4.2K is extrinsic and caused by Sn on the degraded surface, whereas its intrinsic bulk superconducting transition occurs at 1.178 K. These findings make CaSn3 a promising candidate for exploring new exotic states arising from the interplay between non-trivial band topology and superconductivity, e.g. topological superconductivityComment: 20 pages,4 figure

Carbonyl sulfide exchange in a temperate loblolly pine forest grown under ambient and elevated CO2

Vegetation, soil and ecosystem level carbonyl sulfide (COS) exchange was observed at Duke Forest, a temperate loblolly pine forest, grown under ambient (Ring 1, R1) and elevated (Ring 2, R2) CO2. During calm meteorological conditions, ambient COS mixing ratios at the top of the forest canopy followed a distinct diurnal pattern in both CO2 growth regimes, with maximum COS mixing ratios during the day (R1=380±4 pptv and R2=373±3 pptv, daytime mean ± standard error) and minimums at night (R1=340±6 pptv and R2=346±5 pptv, nighttime mean ± standard error) reflecting a significant nighttime sink. Nocturnal vegetative uptake (−11 to −21 pmol m−2s−1, negative values indicate uptake from the atmosphere) dominated nighttime net ecosystem COS flux estimates (−10 to −30 pmol m−2s−1) in both CO2 regimes. In comparison, soil uptake (−0.8 to −1.7 pmol m−2 s−1) was a minor component of net ecosystem COS flux. In both CO2 regimes, loblolly pine trees exhibited substantial COS consumption overnight (50% of daytime rates) that was independent of CO2 assimilation. This suggests current estimates of the global vegetative COS sink, which assume that COS and CO2 are consumed simultaneously, may need to be reevaluated. Ambient COS mixing ratios, species specific diurnal patterns of stomatal conductance, temperature and canopy position were the major factors influencing the vegetative COS flux at the branch level. While variability in branch level vegetative COS consumption measurements in ambient and enhanced CO2 environments could not be attributed to CO2 enrichment effects, estimates of net ecosystem COS flux based on ambient canopy mixing ratio measurements suggest less nighttime uptake of COS in R2, the CO2 enriched environment

Metallic state in La-doped YBa2_2Cu3_3Oy_y thin films with nn-type charge carriers

We report hole and electron doping in La-doped YBa$_2$Cu$_3$O$_y$(YBCO) thin films synthesized by pulsed laser deposition technique and subsequent \emph{in-situ} postannealing in oxygen ambient and vaccum. The $n$-type samples show a metallic behavior below the Mott limit and a high carrier density of $\sim2.8$ $\times$ 10$^{21}$ cm$^{-3}$ at room temperature (\emph{T}) at the optimally reduced condition. The in-plane resistivity ($\rho$$_{ab}$) of the $n$-type samples exhibits a quadratic \emph{T} dependence in the moderate-\emph{T} range and shows an anomaly at a relatively higher \emph{T} probably related to pseudogap formation analogous to underdoped Nd$_{2-x}$Ce$_x$CuO$_4$ (NCCO). Furthermore, $\rho$$_{ab}$(T), \emph{T}$_c$ and \emph{T} with minimum resistivity (\emph{T}$_{min}$) were investigated in both $p$- and $n$-side. The present results reveal the $n$-$p$ asymmetry (symmetry) within the metallic-state region in an underdoped cuprate and suggest the potential toward ambipolar superconductivity in a single YBCO system.Comment: 4 pages, 5 figure