Capillarity-driven dynamics of water–alcohol mixtures in nanofluidic channels

We investigated the spontaneous capillarity-driven filling of nanofluidic channels with a thickness of 6 and 16 nm using mixtures of ethanol and water of variable composition. To improve the visibility of the fluid, we embedded metal mirrors into the top and bottom walls of the channels that act as a Fabry–Pérot interferometer. The motion of propagating liquid–air menisci was monitored for various concentrations in transmission with an optical microscope. In spite of the visible effects of surface roughness and different affinity of water and ethanol to the channel walls, the dynamics followed the classical t 1/2—dependence according to Lucas and Washburn. While the prefactor of this algebraic relation falls short of the expectations based on bulk properties by 10–30%, the relative variation between mixtures of different composition follows the expectations based on the bulk surface tension and viscosity, implying that—despite the small width of the channels and the large surface-to-volume ratio—specific adsorption or chemical selectivity effects are not relevant. We briefly discuss the impact of surface roughness on our experimental results

Giant nonlinear response of superconducting single crystal niobium in a sweeping magnetic field

Giant enhancement of the nonlinear response of a single crystal of Nb placed in a sweeping magnetic field has been experimentally observed. The rectified signal from Nb ($Tc=9.15$ K) has been measured by means of an inductive method as a function of temperature, dc field, dc field sweep rate, and the amplitude of ac field. The Nb sample was excited by an amplitude modulated ac field. Under a stationary regime, the rectified signal appears only for magnetic fields ($H_0$) in the range $H_{c2}<H_0<H_{c3}$ . However, when the dc field was swept slowly, the rectified signal appears at $H_0>H_{c1}$. This experiment shows that the amplitude of the rectified signal is two orders of magnitude larger than the amplitude of the signal seen under stationary field conditions. Moreover, the amplitude of the rectified signal is a power function of the sweep rate, with the power exponent close to 1.Comment: 3 pages, 3 figures, presented to EUCAS 200

Tracking Brazilian Exchange Rate Volatility

This paper examines the relation between dollar-real exchange rate volatility implied in option prices and subsequent realized volatility. It investigates whether implied volatilities contain information about volatility over the remaining life of the option which is not present in past returns. Using GMM estimation consistent with telescoping observations evidence suggests that implied volatilities give superior forecasts of realized volatility if compared to GARCH(p,q), and Moving Average predictors, and that econometric models forecasts do not provide significant incremental information to that contained in implied volatilities.implied volatility, telescoping observations, GMM

Towards diagnosis of rotator cuff tears in 3-D MRI using 3-D convolutional neural networks

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Duality and canonical extensions for stably compact spaces

We construct a canonical extension for strong proximity lattices in order to give an algebraic, point-free description of a finitary duality for stably compact spaces. In this setting not only morphisms, but also objects may have distinct pi- and sigma-extensions.Comment: 29 pages, 1 figur

Electrical conductive double-walled carbon nanotubes � Silica glass nanocomposites prepared by the sol�gel process and spark plasma sintering

The electrical conductivity of suspensions in liquid of several kinds of carbon nanotubes (CNTs) is measured. Raw and soft-functionalized double-walled carbon nanotubes (DWCNTs) appear to be the most promising for achieving a low electrical percolation threshold. A 0.35 vol.% DWCNTs�SiO2 nanocomposite is prepared by the sol�gel process and densified by spark plasma sintering. The obtained material presents a fairly good dispersion of DWCNTs and its electrical conductivity (104 S cm1) is six orders of magnitude higher than that previously reported for 1 vol.% multi-walled CNTs�SiO2

Mean Value of the Class Number in Function Fields Revisited

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this recordIn this paper an asymptotic formula for the sum ∑ (1, χ) is established for the family of quadratic Dirichlet L-functions over the rational function field over a finite field Fq with q fixed. Using the recent techniques developed by Florea we obtain an extra lower order terms that was never been predicted in number fields and function fields. As a corollary, we obtain a formula for the average of the class number over function fields which also contains strenuous lower order terms and so improving on previous results of Hoffstein and Rosen.The first author is grateful to the Leverhulme Trust (RPG-2017-320) for the support through the research grant “Moments of L-functions in Function Fields and Random Matrix Theory”. The second author was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(NRF-2017R1D1A1B03031464)