Effects of long-term farmyard manure applications on soil organic matter, nitrogen mineralization and crop yield – a modeling study –

To develop sustainable cropping systems we need to predict both short-term and long-term effects of management practices on soil fertility. For this purpose agro-ecosystem simulation models are valuable tools. We used the Daisy model to simulate a three-year crop rotation (beetroot, onion, white clover, potato) over a period of 40 years. With this rotation, three rates of farmyard manure were tested (0, 15, 28 t ha-1 year-1). After 40 years without manure soil organic matter carbon (SOM-C) decreased by approximately 40%, and increased by 27% with the highest application rate. SOM turnover did not reach equilibrium at the end of the experiment. Nitrogen mineralization from SOM followed in the long-term (40 years) the slowly changing time courses of SOM. However, manure applications affected mineralization and hence crop yield and nitrogen losses much more in the short-term (1 to 2 years) than in the long-term

Impurity and Trace Tritium Transport in Tokamak Edge Turbulence

The turbulent transport of impurity or minority species, as for example Tritium, is investigated in drift-Alfv\'en edge turbulence. The full effects of perpendicular and parallel convection are kept for the impurity species. The impurity density develops a granular structure with steep gradients and locally exceeds its initial values due to the compressibility of the flow. An approximate decomposition of the impurity flux into a diffusive part and an effective convective part (characterized by a pinch velocity) is performed and a net inward pinch effect is recovered. The pinch velocity is explained in terms of Turbulent Equipartition and is found to vary poloidally. The results show that impurity transport modeling needs to be two-dimensional, considering besides the radial direction also the strong poloidal variation in the transport coefficients.Comment: 12 Pages, 5 Figure

A fast edge charge exchange recombination spectroscopy system at the ASDEX Upgrade tokamak

In this work, a new type of high through-put Czerny-Turner spectrometer has been developed which allows us to acquire multiple channels simultaneously with a repetition time on the order of 10 μ s at different wavelengths. The spectrometer has been coupled to the edge charge exchange recom- bination system at ASDEX Upgrade which has been recently refurbished with new lines of sight. Construction features, calibration methods, and initial measurements obtained with the new setup will be presented.European Commission (EUROfusion 633053

On the mutual effect of ion temperature gradient instabilities and impurity peaking in the reversed field pinch

The presence of impurities is considered in gyrokinetic calculations of ion temperature gradient (ITG) instabilities and turbulence in the reversed field pinch device RFX-mod. This device usually exhibits hollow Carbon/Oxygen profiles, peaked in the outer core region. We describe the role of the impurities in ITG mode destabilization, and analyze whether ITG turbulence is compatible with their experimental gradients.Comment: 19 pages, 9 figures, accepted for publication in Plasma Phys. Control. Fusio

Reflection Types and Students’ Viewing of Feedback in a First-Year Engineering Course Using Standards-Based Grading

Background: Feedback is one of the most powerful and essential tools for learning and assessment, particularly when it provides the information necessary to close an existing gap between actual and reference levels of performance. The literature on feedback has primarily focused on addressing strategies for providing effective feedback rather than aspects of students’ readiness to engage with feedback. Purpose/Hypothesis: This study investigated whether reflection, as a routine pedagogical intervention grounded in self-regulated learning theory, promotes the frequency with which students view feedback. Design/Method: A quasi-experimental design was employed to examine the relationship between the use of four different reflection types, as well as no reflection, and students’ feedback viewing behaviors in a first-year engineering course that used standards-based grading. Clickstream data were gathered through the learning management system to count the number of times students viewed feedback. The number of feedback views was compared by reflection type using descriptive statistics and a generalized linear model; weekly feedback viewing patterns were examined using time-descriptive graphs and the time-series cluster analysis. Results: Findings suggest reflection has the potential to increase the frequency of feedback views. Reflection not only had a positive and significant effect on the number of times students viewed feedback but also resulted in less variability between course sections and instructors when structured reflections made explicit references to feedback. Conclusions: Students need feedback to learn effectively, but many do not view feedback without formal prompting. The authors recommend instructors consistently administer reflections that include explicit pointers to feedback throughout the semester