Marketable yield quantity and quality of leek and residual soil mineral nitrogen in relation to nitrogen fertilization

In Flanders threshold values of soil mineral nitrogen (Nmin) in the soil profile (0-90 cm) in autumn are used in legislation to judge fertilization practices and evaluate the nitrate (NO3-) leaching risk during winter. The average Nmin measured in leek fields are high compared to most arable crops. The objective of this study was to investigate if high Nmin values at harvest can be decreased without reducing yield quantity and quality. We re-analyzed Flemish leek field experiments with various nitrogen (N) fertilizer application rates (2001-2016). We examined marketable yield quantity and quality and residual soil mineral N (RSMN) to rooting depth (0-60 cm) at harvest from July till April the next year. Considering the N supply (= applied effective N + Nmin (0-60 cm) at planting), the marketable yield was on average higher in July till December than in January till April. The maximum marketable yield was obtained at ≈150-200 kg N supply ha‑1. Generally RSMN values measured in July till December were higher than those in January till April. This can be explained by higher N mineralization rates in the first case and possibly some NO3- leaching in the latter case. There was no significant difference in scores of abrasion hardness nor leaf color or uniformity at ≈150-200 kg N supply ha‑1 compared to higher N supplies. Taking into account a mean Nmin value (0-60 cm) at planting of 69±45 kg N ha‑1 (average±standard deviation), effective N application rates in the order of 80-130 kg N ha‑1 are maximum, which allows Nmin values below 50 and 70 kg N ha‑1 in the 0-60 cm and 0-90 cm layer, respectively. These results indicate that N fertilization advices of leek can be reduced without risking a decreased marketable yield quantity and quality but minimizing NO3- leaching during winter

Deformations of Closed Strings and Topological Open Membranes

We study deformations of topological closed strings. A well-known example is the perturbation of a topological closed string by itself, where the associative OPE product is deformed, and which is governed by the WDVV equations. Our main interest will be closed strings that arise as the boundary theory for topological open membranes, where the boundary string is deformed by the bulk membrane operators. The main example is the topological open membrane theory with a nonzero 3-form field in the bulk. In this case the Lie bracket of the current algebra is deformed, leading in general to a correction of the Jacobi identity. We identify these deformations in terms of deformation theory. To this end we describe the deformation of the algebraic structure of the closed string, given by the BRST operator, the associative product and the Lie bracket. Quite remarkably, we find that there are three classes of deformations for the closed string, two of which are exemplified by the WDVV theory and the topological open membrane. The third class remains largely mysterious, as we have no explicit example.Comment: 50 pages, LaTeX; V2: minor changes, 2 references added, V3: typos corrected, signs added, modified discussion on higher correlator

Fission Hindrance in hot 216Th: Evaporation Residue Measurements

The fusion evaporation-residue cross section for 32S+184W has been measured at beam energies of E_beam = 165, 174, 185, 196, 205, 215, 225, 236, 246,and 257 MeV using the ATLAS Fragment Mass Analyzer. The data are compared with Statistical Model calculations and it is found that a nuclear dissipation strength, which increases with excitation energy, is required to reproduce the excitation function. A comparison with previously published data show that the dissipation strength depends strongly on the shell structure of the nuclear system.Comment: 15 pages 9 figure

Optimal energy management for a flywheel-based hybrid vehicle

This paper presents the modeling and design of an optimal Energy Management Strategy (EMS) for a flywheel-based hybrid vehicle, that does not use any electrical motor/generator, or a battery, for its hybrid functionalities. The hybrid drive train consists of only low-cost components, such as a flywheel module and a continuously variable transmission. This hybrid drive train is characterized by a relatively small energy capacity (flywheel) and discrete shifts between operation modes, due to the use of clutches. The main design criterion of the optimized EMS is the minimization of the overall fuel consumption, over a pre-defined driving cycle. In addition, comfort criteria are formulated as constraints, e.g., to avoid high-frequent shifting between driving modes. The criteria are used to find the optimal sequence of driving modes and the generated engine torque. Simulations show a fuel saving potential of 20% to 39%, dependent on the chosen driving cycle