Nährstoff- und Humusbilanzen auf ökologisch wirtschaftenden Marktfruchtbetrieben in Österreich

Für 15 ausgewählte österreichische Öko-Ackerbaubetriebe wurden N-, P-, K- und Humusbilanzen berechnet. Im Durchschnitt waren die Nährstoffbilanzen leicht negativ, die Humusbilanzen positiv, mit großer Spannweite. Das Nährstoffmonitoring und -management auf diesen Betrieben ist verbesserungsbedürfti

Influence of through-flow on linear pattern formation properties in binary mixture convection

We investigate how a horizontal plane Poiseuille shear flow changes linear convection properties in binary fluid layers heated from below. The full linear field equations are solved with a shooting method for realistic top and bottom boundary conditions. Through-flow induced changes of the bifurcation thresholds (stability boundaries) for different types of convective solutions are deter- mined in the control parameter space spanned by Rayleigh number, Soret coupling (positive as well as negative), and through-flow Reynolds number. We elucidate the through-flow induced lifting of the Hopf symmetry degeneracy of left and right traveling waves in mixtures with negative Soret coupling. Finally we determine with a saddle point analysis of the complex dispersion relation of the field equations over the complex wave number plane the borders between absolute and convective instabilities for different types of perturbations in comparison with the appropriate Ginzburg-Landau amplitude equation approximation. PACS:47.20.-k,47.20.Bp, 47.15.-x,47.54.+rComment: 19 pages, 15 Postscript figure

Influence of the Soret effect on convection of binary fluids

Convection in horizontal layers of binary fluids heated from below and in particular the influence of the Soret effect on the bifurcation properties of extended stationary and traveling patterns that occur for negative Soret coupling is investigated theoretically. The fixed points corresponding to these two convection structures are determined for realistic boundary conditions with a many mode Galerkin scheme for temperature and concentration and an accurate one mode truncation of the velocity field. This solution procedure yields the stable and unstable solutions for all stationary and traveling patterns so that complete phase diagrams for the different convection types in typical binary liquid mixtures can easily be computed. Also the transition from weakly to strongly nonlinear states can be analyzed in detail. An investigation of the concentration current and of the relevance of its constituents shows the way for a simplification of the mode representation of temperature and concentration field as well as for an analytically manageable few mode description.Comment: 30 pages, 12 figure

Higgs production and decay: Analytic results at next-to-leading order QCD

The virtual two-loop corrections for Higgs production in gluon fusion are calculated analytically in QCD for arbitrary Higgs and quark masses. Both scalar and pseudo-scalar Higgs bosons are considered. The results are obtained by expanding the known one-dimensional integral representation in terms of m_H/m_q, and matching it with a suitably chosen ansatz of Harmonic Polylogarithms. This ansatz is motivated by the known analytic result for the Higgs decay rate into two photons. The method also allows us to check this result and to extend it to the pseudo-scalar decay rate.Comment: LaTeX, 16 pages, 5 figures (8 eps-files

Convection in Binary Fluid Mixtures. II. Localized Traveling Waves. (Physical Review E, in press)

Nonlinear, spatially localized structures of traveling convection rolls are investigated in quantitative detail as a function of Rayleigh number for two different Soret coupling strengths (separation ratios) with Lewis and Prandtl numbers characterizing ethanol-water mixtures. A finite-difference method was used to solve the full hydrodynamic field equations numerically. Structure and dynamics of these localized traveling waves (LTW) are dominated by the concentration field. Like in the spatially extended convective states ( cf. accompanying paper), the Soret-induced concentration variations strongly influence, via density changes, the buoyancy forces that drive convection. The spatio-temporal properties of this feed-back mechanism, involving boundary layers and concentration plumes, show that LTW's are strongly nonlinear states. Light intensity distributions are determined that can be observed in side-view shadowgraphs. Detailed analyses of all fields are made using colour-coded isoplots, among others. In the frame comoving with their drift velocity, LTW's display a nontrivial spatio-temporal symmetry consisting of time-translation by half an oscillation period combined with vertical reflection through the horizontal midplane of the layer. A time-averaged concentration current is driven by a phase difference between the waves of concentration and vertical velocity in the bulk of the LTW state. The associated large-scale concentration redistribution stabilizes the LTW and controls its drift velocity into the quiescent fluid by generating a buoyancy-reducing concentration "barrier" ahead of the leading LTW front. The selection of the width of the LTW's is investigated and comparisons with experiments are presented.Comment: 18 pages and 6 figures as uuencoded Postscript file (using uufiles) 1 color figure as uuencoded Postscript file, a high resolution version of the color figure (about 10MB) can be requested from [email protected] or [email protected].: (Barten)present address: PSI, CH-5232 Villigen PSI, Switzerlan

Cutaneous lesions of the nose

Skin diseases on the nose are seen in a variety of medical disciplines. Dermatologists, otorhinolaryngologists, general practitioners and general plastic and dermatologic surgeons are regularly consulted regarding cutaneous lesions on the nose. This article is the second part of a review series dealing with cutaneous lesions on the head and face, which are frequently seen in daily practice by a dermatologic surgeon. In this review, we focus on those skin diseases on the nose where surgery or laser therapy is considered a possible treatment option or that can be surgically evaluated

Neutral pathways and heat flux widths in vertical- and horizontal-target EDGE2D-EIRENE simulations of JET

This paper further analyses the EDGE2D-EIRENE simulations presented by Chankin et al (2017 Nucl. Mater. Energy 12 273), of L-mode JET plasmas in vertical-vertical (VV) and Vertical-horizontal (VH) divertor configurations. As expected, the simulated outer divertor ionisation source peaks near the separatrix in VV and radially further out in VH. We identify the reflections of recycled neutrals from lower divertor tiles as the primary mechanism by which ionisation is concentrated on the outer divertor separatrix in the VV configuration. These lower tile reflection pathways (of neutrals from the outer divertor, and to an even greater extent from the inner divertor) dominate the outer divertor separatrix ionisation. In contrast, the lower-tile-reflection pathways are much weaker in the VH simulation and its outer divertor ionisation is dominated by neutrals which do not reflect from any surfaces. Interestingly, these differences in neutral pathways give rise to strong differences in the heat flux density width λq at the outer divertor entrance: λq = 3.2 mm in VH compared to λq = 11.8 mm in VV. In VH, a narrow channel exists in the near scrape-off-layer (SOL) where the convected heat flux, driven by strong Er × B flow and thermoelectric current, dominates over the conducted heat flux. The width of this channel sets λq and is determined by the radial distance between the separatrix and the ionisation peak in the outer divertor

Observations and modelling of ion cyclotron emission observed in JET plasmas using a sub-harmonic arc detection system during ion cyclotron resonance heating

Peer reviewe

Investigation into the formation of the scrape-off layer density shoulder in JET ITER-like wall L-mode and H-mode plasmas

The low temperature boundary layer plasma (Scrape-Off-Layer or SOL) between the hot core and the surrounding vessel determines the level of power-loading, erosion and implantation of material surfaces, and thus the viability of tokamak-based fusion as an energy source. This study explores mechanisms affecting the formation of flattened density profiles, so-called ‘density shoulders’, in the low-field side (LFS) SOL, which modify ion and neutral fluxes to surfaces – and subsequent erosion. There is evidence against local enhancement of ionization inducing shoulder formation. We find that increases in SOL parallel resistivity, Λdiv (=[L||νei Ωi ]/cs Ωe), postulated to lead to shoulder growth through changes in SOL turbulence characteristics, correlates with increases in upstream SOL shoulder amplitude, As only under a subset of conditions (D2-fuelled L-mode density scans with outer strike point on the horizontal target). Λdiv fails to correlate with As for cases of N2 seeding or during sweeping of the strike point across the horizontal target. The limited correlation of Λdiv with As was also found for H-mode discharges. Thus, while Λdiv above a threshold of ~1 may be necessary for shoulder formation and/or growth, another shoulder mechanism is required. More significantly we find that in contrast to parallel resistivity, outer divertor recycling as quantified by the total outer divertor Balmer Dα emission, I-Dα, does scale with shoulder amplitude where Λdiv does and even where Λdiv fails. Divertor recycling could lead to SOL density shoulder formation through: a) reducing the parallel to the field flow (loss) of ions out of the SOL to the divertor; and b) changes in radial electric fields which lead to ExB poloidal flows as well as potentially affecting the SOL turbulence birth characteristics. Thus changes in divertor recycling may be the sole process in bringing about SOL density shoulders or in tandem with parallel resistivity