Over-Improved Stout-Link Smearing

A new over-improved stout-link smearing algorithm, designed to stabilise instanton-like objects, is presented. A method for quantifying the selection of the over-improvement parameter, $\epsilon$, is demonstrated. The new smearing algorithm is compared with the original stout-link smearing, and Symanzik improved smearing through calculations of the topological charge and visualisations of the topological charge density.Comment: 9 pages, 18 figures, submitted to Physical Review

Agronomic evaluation of bone char as phosphorus fertiliser after five years of consecutive application

Knochenkohle (BC), hergestellt mittels einer technischen Pyrolyse von entfetteten Tierknochen aus Schlachtabfällen, könnte ein vielversprechender Phosphor (P) Recyc­lingdünger sein. Agronomische Bewertungen aus Langzeitversuchen fehlen jedoch bisher. Phosphor in BC (15% P) ist überwiegend in Strukturen ähnlich dem Hydroxy­lapatit (HA) gebunden. Es kann davon ausgegangen werden, dass in HA gebundener P aufgrund geringer Löslichkeit keine große Düngewirkung erzielt. Eine bessere Löslichkeit wird von Schwefel angereicherter BC (BCplus) erwar­tet.2013 wurde ein Feldversuch angelegt, um das Düngepotenzial von BC und BCplus im Vergleich zu P0 und Triple Superphosphat (TSP) zu testen. In Abhängigkeit der durchschnittlichen PCAL-Konzentration im Boden (0–30 cm) wurden Parzellen den Boden-P-Gehaltsklasse A (11 mg kg–1 PCAL), B (21 mg kg–1 PCAL), und C (47 mg kg–1 PCAL) zugeordnet. In Boden-P-Gehaltklasse A stieg der mittlere Relativertrag kumuliert für die erste Fruchtfolge (Wintergerste, Winterraps, Winterweizen, Lupine, Winterroggen) in der Reihenfolge P0 (90 %) < BC (94 %) < BCplus (95 %) < TSP (100 %) an. Die relative P-Auf­nahme (Korn) wurde durch die Düngevarianten in Boden-P-Gehaltsklasse A in der Reihenfolge P0 (81 %) < BC (88 %) < BCplus (91 %) < TSP (100 %) und in Klasse B von P0 (84 %) < BCplus (90 %) < BC (92 %) < TSP (100 %) beeinflusst. Bei ausreichender P-Versorgung (Boden-P-Gehaltsklasse C) wurde im Fruchtfolgemittel kein Dünger­einfluss auf die Ertragsbildung und die P-Auf­nahme beobachtet. Die PCAL-Konzentration im Boden wurde ausschließlich durch die Anwendung von TSP erhöht. Ausgehend von einer ausreichenden P-Versorgung (Boden-P-Gehaltsklasse C) werden weitere Versuchsjahre zeigen, ob Knochenkohlen in der Lage sind, die Nährstoffversorgung von Kulturpflanzen mit P langfristig zu gewährleisten.Bone char (BC), pyrolyzed defatted bones from slaughterhouse waste, may be a promising secondary raw material to produce phosphorus (P) fertiliser, but its agronomic value has not yet been shown in longer-term field experi­ments. Phosphorus in BC (15 % P) is mainly bound in a structure similar to hydroxylapatite (HA). Generally, P in HA is of low solubility and, consequently, it can be expected that bones or BC have a low fertilisation value. Better solubility of P is expected from BC enriched with sulphur (BCplus). In 2013, a field experiment was established to test the fertilisation potential of BC and BCplus compared to a control (P0) and triple super phosphate (TSP) treatment. According to their mean PCAL concentrations (0–30 cm) plots were assigned to the initial soil P-test class (iSPTC) A (11 mg kg–1 PCAL), B (21 mg kg–1 PCAL), and C (47 mg kg–1 PCAL). After a first crop rotation an increased cumulative yield was determined for iSPTC-A depending on the fertiliser treatment with means of relative yield of P0 (90 %) < BC (94 %) < BCplus (95 %) < TSP (100 %). Effects on the relative P uptake of grain in iSPTC-A depending on the fertiliser treatment were in the order of P0 (81 %) < BC (88 %) < BCplus (91 %) < TSP (100 %) and in iSPTC-B of P0 (84 %) < BCplus (90 %) < BC (92 %) < TSP (100 %). Fertiliser treatments had no effect on mean yield and P uptake in the first crop rotation if initially sufficient soil P (iSPTC-C) was available. An increase of PCAL concentrations was only achieved by TSP fertilisation. Future experimental years will show, if BC fertilisers are able to maintain sufficient P availability to crops in the long term

Panel discussion on chiral extrapolation of physical observables

This is an approximate reconstruction of the panel discussion on chiral extrapolation of physical observables. The session consisted of brief presentations from panelists, followed by responses from the panel, and concluded with questions and comments from the floor with answers from panelists. In the following, the panelists have summarized their statements, and the ensuing discussion has been approximately reconstructed from notes.Comment: Lattice2002(plenary) 15 pages, 3 figure

Sulfur-enriched bone char enhances P uptake by maize in a perennial pot experiment

Phosphor (P)-Recycling aus Schlachtabfällen, Herstellung von Knochenkohle und deren Einsatz als Dünger ist ein vielversprechender Ansatz zum Schließen von Nährstoffkreisläufen, jedoch ist die Düngewirkung der Knochenkohle noch unklar. Deshalb wurden zwei Knochenkohlen (Knochenkohle (BC) und Knochenkohleplus (BCplus; schwefelangereicherte BC)) im Vergleich zu Triplesuperphosphat (TSP) in einem mehrjährigen Gefäßversuch mit Mais als stark P-abhängiger Fruchtart getestet. Die untersuchten Düngemittel beeinflussten sowohl die Trockenmasse als auch die P-Konzentration von Mais in der Reihenfolge BCplus, TSP &gt; BC. Die P-Aufnahme von Mais in der TSP-Variante erreichte im ersten Versuchsjahr 38 % des applizierten P und nahm in den Folgejahren stetig ab. Die P-Aufnahme in der BCplus-Variante blieb dagegen während der Versuchsdauer relativ konstant. Daraus folgt, dass der Recycling-P-Dünger BCplus eine ausreichende P-Verfügbarkeit für Nutzpflanzen langfristig aufrechterhalten kann.Recycling of phosphorus (P) from slaughterhouse waste, production of bone char (BC) and its use as fertilizer is a promising approach to close nutrient cycles but the fertilizer value of BC is not sufficiently clear. Therefore, two BCs (BC and sulfur-enriched BC (BCplus)) were tested in comparison with highly water-soluble triple superphosphate (TSP) in a perennial pot experiment with maize as test plant with high P-requirement. The fertilizers affected both the dry matter yields, and the P concentration of maize in the general order BCplus, TSP &gt; BC. The P uptake of maize in the TSP treatment accounted for 38% of the applied P in the first experimental year and decreased subsequently. By contrast, the P uptake in the BCplus treatment remained quite stable over time. In conclusion, the sulfur-enriched BCplus is able to maintain sufficient P availability to crops in the medium term and can be recommended as fertilizer

Low-lying Odd-parity States of the Nucleon in Lattice QCD

The world's first examination of the odd-parity nucleon spectrum at light quark masses in 2+1 flavor lattice QCD is presented. Configurations generated by the PACS-CS collaboration and made available through the ILDG are used, with the lightest pion mass at 156 MeV. A novel method for tracking the individual energy eigenstates as the quark mass changes is introduced. The success of this approach reveals the flow of the states towards the physical masses. Using the correlation matrix method, the two lowest-energy states revealed are found to be in accord with the physical spectrum of Nature.Comment: 5 page

Roper Resonance in 2+1 Flavor QCD

The low-lying even-parity states of the nucleon are explored in lattice QCD using the PACS-CS collaboration 2+1-flavor dynamical-QCD gauge-field configurations made available through the International Lattice Datagrid (ILDG). The established correlation-matrix approach is used, in which various fermion source and sink smearings are utilized to provide an effective basis of interpolating fields to span the space of low-lying energy eigenstates. Of particular interest is the nature of the first excited state of the nucleon, the $N{1/2}^{+}$ Roper resonance of $P_{11}$ pion-nucleon scattering. The Roper state of the present analysis approaches the physical mass, displaying significant chiral curvature at the lightest quark mass. These full QCD results, providing the world's first insight into the nucleon mass spectrum in the light-quark regime, are significantly different from those of quenched QCD and provide interesting insights into the dynamics of QCD.Comment: 7 pages, 5 figures. Revised version with new results to appear in PL

Impact of stout-link smearing in lattice fermion actions

The impact of stout-link smearing in lattice fermion actions is examined through the consideration of the mass and renormalization functions of the overlap quark propagator over a variety of smeared configurations. Up to six sweeps of stout-link smearing are investigated. For heavy quark masses, the quark propagator is strongly affected by the smearing procedure. For moderate masses, the effect appears to be negligible. A small effect is seen for light quark masses, where dynamical mass generation is suppressed through the smearing procedure.Comment: 7 pages, 3 figures, presented at the XXVII International Symposium on Lattice Field Theory - LAT2009, July 26-31 2009, Peking University, Beijing, Chin

Stout-link smearing in lattice fermion actions

The properties of the momentum space quark propagator in Landau gauge are studied for the overlap quark action in quenched lattice QCD. Numerical calculations are performed over four ensembles of gauge configurations, where three are smeared using either 1, 3, or 6 sweeps of stout-link smearing. We calculate the non-perturbative wave function renormalization function $Z(p)$ and the non-perturbative mass function $M(p)$ for a variety of bare quark masses. We find that the wave-function renormalization function is slightly sensitive to the number of stout-link smearing sweeps. For the mass function we find the effect of the stout-link smearing algorithm to be small for moderate to light bare quark masses. For a heavy bare quark mass we find a strong dependence on the number of smearing sweeps.Comment: 8 pages, 4 figure

Phosphorus speciation in long-term drained and rewetted peatlands of northern germany

Previous studies, conducted at the inception of rewetting degraded peatlands, reported that rewetting increased phosphorus (P) mobilization but long-term effects of rewetting on the soil P status are unknown. The objectives of this study were to (i) characterize P in the surface and subsurface horizons of long-term drained and rewetted percolation mires, forest, and coastal peatlands and (ii) examine the influence of drainage and rewetting on P speciation and distributions using wet-chemical and advanced spectroscopic analyses. The total P was significantly (p < 0.05) different at the surface horizons. The total concentration of P ranged from 1022 to 2320 mg kg−1 in the surface horizons and decreased by a factor of two to five to the deepest horizons. Results of the chemical, solution 31P nuclear magnetic resonance (NMR), and P K-edge X-ray absorption near-edge structure (XANES) indicated that the major proportions of total P were organic P (Po). In the same peatland types, the relative proportions of Po and stable P fractions were lower in the drained than in the rewetted peatland. The results indicate that long-term rewetting not only locks P in organic matter but also transforms labile P to stable P fractions at the surface horizons of the different peatland types. © 2020 by the authors. Licensee MDPI, Basel, Switzerland