Implementatie van sensorgestuurde stikstof-bijbemesting in pootaardappel

In 2010 en 2011 is de stikstofbijbemesting volgens verschillende strategieën op drie aparte stroken uitgevoerd op een praktijkperceel met aardappelpootgoed (ras Mustang) in Vierhuizen (Groningen). Op elke strook werden tevens twee stikstofvensters aan gelegd. Op één venster werd geen basisbemesting toegepast en het andere kreeg de dubbele hoeveelheid stikstof bij de basisbemesting. Op de stroken en de vensters werden netto waarnemingsvelden uitgezet waarop vier maal monsters werden genomen voor aardappelmonitoring (Altic). Op de velden werden tevens sensorwaarnemingen gedaan op de dag van monstername. Uit de sensorwaarnemingen en aardappelmonitoring werden N-bijmestadviezen afgeleid. Op de landbouwspuit van de ondernemer (de heer Claassen) zijn gewassensoren gemonteerd. Met deze sensoren werd in de periode van bijbemesting de gewasreflectie van het hele perceel opgenomen. Aan de hand van de handmetingen met de CropScan Sensor werd beoordeeld of de sensorgegevens van de CropCircle bruikbare informatie geven om een N bijmestadvies af te leiden. Bovendien is beoordeeld of de stappen om tot een stikstof bijmestadvies te komen uitvoerbaar en betrouwbaar zijn. De conclusie luidt dat de hoogte van de adviezen op basis van de CropScan in dezelfde orde van grootte liggen als de praktijkbemesting. De sensoren registreren plekken met een lagere en hogere bemesting en het advies dat daaruit wordt afgeleid (methode Booij) is realistisch. De praktijksensor bleek echter niet betrouwbaar. Het verband van de waarden van de geijkte en gekalibreerde CropScan sensor was slecht. Vermoedelijk is er een defect in één van de sensoren. Dit wijst op de hoge noodzaak van periodieke controle van de sensoren en een protocol voor ijking en kalibratie. Alleen dan is het mogelijk de sensor in te zetten voor bijmestsystemen

Subtraction terms at NNLO

Perturbative calculations at next-to-next-to-leading order for multi-particle final states require a method to cancel infrared singularities. I discuss the subtraction method at NNLO. As a concrete example I consider the leading-colour contributions to e+ e- --> 2 jets. This is the simplest example which exhibits all essential features. For this example, explicit subtraction terms are given, which approximate the four-parton and three-parton final states in all double and single unresolved limits, such that the subtracted matrix elements can be integrated numerically.Comment: 41 page

Alfven eigenmode stability and fast ion loss in DIII-D and ITER reversed magnetic shear plasmas

Neutral beam injection into reversed-magnetic shear DIII-D plasmas produces a variety of Alfvenic activity including ´ toroidicity-induced Alfven eigenmodes (TAEs) and reversed shear Alfv ´ en eigenmodes (RSAEs). With measured ´ equilibrium profiles as inputs, the ideal MHD code NOVA is used to calculate eigenmodes of these plasmas. The postprocessor code NOVA-K is then used to perturbatively calculate the actual stability of the modes, including finite orbit width and finite Larmor radius effects, and reasonable agreement with the spectrum of observed modes is found. Using experimentally measured mode amplitudes, fast ion orbit following simulations have been carried out in the presence of the NOVA calculated eigenmodes and are found to reproduce the dominant energy, pitch and temporal evolution of the losses measured using a large bandwidth scintillator diagnostic. The same analysis techniques applied to a DT 8 MA ITER steady-state plasma scenario with reversed-magnetic shear and both beam ion and alpha populations show Alfven eigenmode instability. Both RSAEs and TAEs are found to be unstable ´ with maximum growth rates occurring for toroidal mode number n = 6 and the majority of the drive coming from fast ions injected by the 1 MeV negative ion beams. AE instability due to beam ion drive is confirmed by the non-perturbative code TAEFL. Initial fast ion orbit following simulations using the unstable modes with a range of amplitudes (δB/B = 10−5–10−3) have been carried out and show negligible fast ion loss. The lack of fast ion loss is a result of loss boundaries being limited to large radii and significantly removed from the actual modes themselves.US Department of Energy DE-FC02-04ER54698, DE-AC02-09CH11466, SC-G903402, DE-AC05-00OR22725, DE-FG03-97ER5441

Fluctuation of the Correlation Dimension and the Inverse Participation Number at the Anderson Transition

The distribution of the correlation dimension in a power law band random matrix model having critical, i.e. multifractal, eigenstates is numerically investigated. It is shown that their probability distribution function has a fixed point as the system size is varied exactly at a value obtained from the scaling properties of the typical value of the inverse participation number. Therefore the state-to-state fluctuation of the correlation dimension is tightly linked to the scaling properties of the joint probability distribution of the eigenstates.Comment: 4 pages, 5 figure

Spectrum of the Vortex Bound States of the Dirac and Schrodinger Hamiltonian in the presence of Superconducting Gaps

We investigate the vortex bound states both Schrodinger and Dirac Hamiltonian with the s-wave superconducting pairing gap by solving the mean-field Bogoliubov-de-Gennes equations. The exact vortex bound states spectrum is numerically determined by the integration method, and also accompanied by the quasi-classical analysis. It is found that the bound state energies is proportional to the vortex angular momentum when the chemical potential is large enough. By applying the external magnetic field, the vortex bound state energies of the Dirac Hamiltonian are almost unchanged; whereas the energy shift of the Schrodinger Hamiltonian is proportional to the magnetic field. These qualitative differences may serve as an indirect evidence of the existence of Majorana fermions in which the zero mode exists in the case of the Dirac Hamiltonian only.Comment: 8 pages, 9 figure

Higgs-Boson Production Associated with a Single Bottom Quark in Supersymmetric QCD

Due to the enhancement of the couplings between Higgs boson and bottom quarks in the minimal sypersymmetric standard model (MSSM), the cross section of the process pp(p\bar{p}) \to h^0b(h^0\bar{b})+X at hadron colliders can be considerably enhanced. We investigated the production of Higgs boson associated with a single high-p_T bottom quark via subprocess bg(\bar{b}g) \to h^0b(h^0\bar{b}) at hadron colliders including the next-to-leading order (NLO) QCD corrections in MSSM. We find that the NLO QCD correction in the MSSM reaches 50%-70% at the LHC and 60%-85% at the Fermilab Tevatron in our chosen parameter space.Comment: accepted by Phys. Rev.

Nine-Propagator Master Integrals for Massless Three-Loop Form Factors

We complete the calculation of master integrals for massless three-loop form factors by computing the previously-unknown three diagrams with nine propagators in dimensional regularisation. Each of the integrals yields a six-fold Mellin-Barnes representation which we use to compute the coefficients of the Laurent expansion in epsilon. Using Riemann zeta functions of up to weight six, we give fully analytic results for one integral; for a second, analytic results for all but the finite term; for the third, analytic results for all but the last two coefficients in the Laurent expansion. The remaining coefficients are given numerically to sufficiently high accuracy for phenomenological applications.Comment: 15 pages, 2 figures. Minor modifications and reference added. Matches published versio

Presidential Popularity and Reputation

This paper reports on the results of an empirical study of relationships between the popularity of US presidents and economic variables. Traditionally, these relationships are based on the hypothesis that voters hold the incumbent President responsible for the economic situation. We derive an alternative specification of popularity, based on the hypothesis that political parties perform better on different issues. Empirical evidence turns out to be strongly in favour of our hypothesis. Our findings have important implications for studies on government behaviour in which it is assumed that one of the objectives of administrations is to maximise votes

Monitoring van groene burgerinitiatieven : analyse van de resultaten van een pilot en nulmeting in vier gemeenten

To inform the evaluation of the Nature Pact (Natuurpact) and the Assessment of the Dutch Human Environment (Balans van de Leefomgeving), PBL Netherlands Environmental Assessment Agency needs a quantitative measure of the size and scope of green citizens’ initiatives and their impact. The need for this information reflects the ambition of many government authorities to bring the wider community, including individuals, into closer contact with nature and involve them more in nature policy. This report describes the results of a baseline assessment and pilot study to test the newly developed methodology for monitoring green citizens’ initiatives. Besides the results, the report includes several analyses based on the data and presents the main findings