Does Fully-Developed Turbulence Exist? Reynolds Number Independence versus Asymptotic Covariance

By analogy with recent arguments concerning the mean velocity profile of wall-bounded turbulent shear flows, we suggest that there may exist corrections to the 2/3 law of Kolmogorov, which are proportional to $(\ln\,\Re)^{-1}$ at large Re. Such corrections to K41 are the only ones permitted if one insists that the functional form of statistical averages at large Re be invariant under a natural redefinition of Re. The family of curves of the observed longitudinal structure function $D_{LL}(r, \Re)$ for different values of Re is bounded by an envelope. In one generic scenario, close to the envelope, $D_{LL}(r, \Re)$ is of the form assumed by Kolmogorov, with corrections of O((\lnRe)^{-2}). In an alternative generic scenario, both the Kolmogorov constant $C_K$ and corrections to Kolmogorov's linear relation for the third order structure function $D_{LLL} (r)$ are proportional to $(\ln\,\Re)^{-1}$. Recent experimental data of Praskovsky and Oncley appear to show a definite dependence of $C_K$ on Re, which if confirmed, would be consistent with the arguments given here.Comment: 13 Pages. Tex file and Postscript figure included in uufiles compressed format. Needs macro uiucmac.tex, available from cond-mat archive or from ftp://gijoe.mrl.uiuc.edu/pu

Quantum and classical surface acoustic wave induced magnetoresistance oscillations in a 2D electron gas

We study theoretically the geometrical and temporal commensurability oscillations induced in the resistivity of 2D electrons in a perpendicular magnetic field by surface acoustic waves (SAWs). We show that there is a positive anisotropic dynamical classical contribution and an isotropic non-equilibrium quantum contribution to the resistivity. We describe how the commensurability oscillations modulate the resonances in the SAW-induced resistivity at multiples of the cyclotron frequency. We study the effects of both short-range and long-range disorder on the resistivity corrections for both the classical and quantum non-equilibrium cases. We predict that the quantum correction will give rise to zero-resistance states with associated geometrical commensurability oscillations at large SAW amplitude for sufficiently large inelastic scattering times. These zero resistance states are qualitatively similar to those observed under microwave illumination, and their nature depends crucially on whether the disorder is short- or long-range. Finally, we discuss the implications of our results for current and future experiments on two dimensional electron gases.Comment: 16 pages, 8 figure

Negative index fishnet with nanopillars formed by direct nano-imprint lithography

In this paper we demonstrate the ability to fabricate fishnets by nanoimprinting directly into a pre-deposited three layer metal–dielectric–metal stack, enabling us to pattern large areas in two minutes. We have designed and fabricated two different fishnet structures of varying dimensions using this method and measured their resonant wavelengths in the near-infrared at 1.45 μm and 1.88 μm. An important by-product of directly imprinting into the metal–dielectric stack, without separation from the substrate, is the formation of rectangular nanopillars that sit within the rectangular apertures between the fishnet slabs. Simulations complement our measurements and suggest a negative refractive index real part with a magnitude of 1.6. Further simulations suggest that if the fishnet were to be detached from the supporting substrate a refractive index real part of 5 and FOM of 2.74 could be obtained

Effect of ultrasound pre-treatment on the physical, microbiological, and antioxidant properties of calçots

The effect of ultrasound (US) treatment (40 kHz, 250 W) for 0, 10,25 and 45 min on the physical and microbiological quality, total antioxidant capacity (TAC) and total phenolic content (TPC) of calçots (Allium cepaL.) was evaluated. Moreover, the effect of roasting (270 °C, 8 min) and in vitro simulated digestion on the antioxidant properties was studied. Overall, US treatment had no effect of the physical quality and antioxidant properties of calçots regardless the treatment time, while thermal processing produced an increase on the TAC and maintenance in TPC. Furthermore, the digestion process caused a remarkable decrease on the TAC and TPC, but that decrease was higher in roasted than in fresh samples. The microbial load of all US-treated fresh samples was below 6 log (cfu g−1) and a decrease of 1-log reduction was observed after treating for 45 min. Those results indicated that US pre-treatment had no negative effects on the quality of calçot while produced a decrease on the microbial load at high processing times.This work was supported by ACCIÓ (Generalitat of Catalonia, RD14-1-004), Sociedad Agrícola i Secció de Crèdit de Valls S.C.C.L., Cooperativa of Cambrils, and PGI ‘Calçot de Valls’. This work was also supported by the ‘Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement’ (FI-2017-B2-00164, L. Zudaire) and CERCA Programme of Generalitat de Catalunya. T. Lafarga is in receipt of a ‘Juan de la Cierva’ contract awarded by the Spanish Ministry of Economy, Industry, and Competitiveness (FJCI-2016-29541). I. Aguiló-Aguayo thanks the National Programme for the promotion of talent and its employability of the ‘Ministerio de Economía,Industria y Competitividad’ of the Spanish Government and to the European Social Fund for the Postdoctoral Senior Grant ‘Ramon y Cajal’ (RYC-2016-19949)

Regulation of protein kinase B and glycogen synthase kinase-3 by insulin and beta-adrenergic agonists in rat epididymal fat cells - Activation of protein kinase B by wortmannin-sensitive and -insensittve mechanisms

Previous studies using L6 myotubes have suggested that glycogen synthase kinase-3 (GSK-3) is phosphoryl ated and inactivated in response to insulin by protein kinase B (PKB, also known as Akt or RAG) (Cross, D, A, E., Alessi, D, R., Cohen, P., Andjelkovic, M., and Hemmings, B, A. (1995) Nature 378, 785-789), In the present study, marked increases in the activity of PKB have been shown to occur in insulin-treated rat epididymal fat cells with a time course compatible with the observed decrease in GSK-3 activity, Isoproterenol, acting primarily through beta(3)-adrenoreceptors, was found to decrease GSK-3 activity to a similar extent (approximately 50%) to insulin, However, unlike the effect of insulin, the inhibition of GSK by isoproterenol was not found to be sensitive to inhibition by the phosphatidylinositol 3'-kinase inhibitors, wortmannin or LY 294002, The change in GSK-3 activity brought about by isoproterenol could not be mimicked by the addition of permeant cyclic AMP analogues or forskolin to the cells, although at the concentrations used, these agents were able to stimulate lipolysis. Isoproterenol, but again not the cyclic AMP analogues, was found to increase the activity of PKB, although to a lesser extent than insulin. While wortmannin abolished the stimulation of PKB activity by insulin, it was without effect on the activation seen in response to isoproterenol, The activation of PKB by isoproterenol was not accompanied by any detectable change in the electrophoretic mobility of the protein on SDS-polyacrylamide gel electrophoresis. It would therefore appear that distinct mechanisms exist for the stimulation of PKB by insulin and isoproterenol in rat fat cells

Vacuum ultraviolet photoabsorption of prime ice analogues of Pluto and Charon

Here we present the first Vacuum UltraViolet (VUV) photoabsorption spectra of ice analogues of Pluto and Charon ice mixtures. For Pluto the ice analogue is an icy mixture containing nitrogen (N2), carbon monoxide (CO), methane (CH4) and water (H2O) prepared with a 100:1:1:3 ratio, respectively. Photoabsorption of icy mixtures with and without H2O were recorded and no significant changes in the spectra due to presence of H2O were observed. For Charon a VUV photoabsorption spectra of an ice analogue containing ammonia (NH3) and H2O prepared with a 1:1 ratio was recorded, a spectrum of ammonium hydroxide (NH4OH) was also recorded. These spectra may help to interpret the P-Alice data from New Horizons

Using the UM dynamical cores to reproduce idealised 3D flows

We demonstrate that both the current (New Dynamics), and next generation (ENDGame) dynamical cores of the UK Met Office global circulation model, the UM, reproduce consistently, the long-term, large-scale flows found in several published idealised tests. The cases presented are the Held-Suarez test, a simplified model of Earth (including a stratosphere), and a hypothetical tidally locked Earth. Furthermore, we show that using simplifications to the dynamical equations, which are expected to be justified for the physical domains and flow regimes we have studied, and which are supported by the ENDGame dynamical core, also produces matching long-term, large-scale flows. Finally, we present evidence for differences in the detail of the planetary flows and circulations resulting from improvements in the ENDGame formulation over New Dynamics.Comment: 34 Pages, 23 Figures. Accepted for publication in Geoscientific Model Development (pre-proof version

The Lennard-Jones-Devonshire cell model revisited

We reanalyse the cell theory of Lennard-Jones and Devonshire and find that in addition to the critical point originally reported for the 12-6 potential (and widely quoted in standard textbooks), the model exhibits a further critical point. We show that the latter is actually a more appropriate candidate for liquid-gas criticality than the original critical point.Comment: 5 pages, 3 figures, submitted to Mol. Phy