Nitrous oxide emissions from organic farming: the importance of well-timed ley cultivation

The period after ploughing of grass-clover within a ley-arable rotation is when nitrogen accumulated during ley cropping is most vulnerable to loss. I investigated how date of ploughing and date of cessation of grazing before ploughing influenced losses of nitrogen as nitrous oxide during establishment of the first cereal crop. Crop nitrogen uptake was also assessed. Nitrous oxide (N2O) emissions in the 1-2 month period after autumn or spring ploughing or after sowing were typically between 20 and 150 g N ha-1 day-1 and increased with temperature and rainfall. Tillage and sowing operations on previously ploughed soil stimulated N2O emissions even several months after ploughing. Cumulative N2O emissions were highest (~8 kg ha-1 over 17 months) after late cessation of grazing and late ploughing, and lowest (~5.5 kg ha-1) after early cessation of grazing and early ploughing. The optimum time of ploughing appears to be midwinter when the cold restricts nitrogen mineralisation, but sufficient nitrogen subsequently becomes available for early spring crop growth and satisfactory N offtake. Restricting tillage operations to cool conditions should help to reduce N2O emissions. However, the soil should also be dry enough to reduce the risk of damage to soil structure

Phenol Deoxygenation over Hydrotreating Catalysts

Phenol deoxygenation has been investigated as a model reaction for the deoxygenation of fatty acid methyl esters in biodiesel. Hydrodeoxygenated biodiesel is a drop-in fuel for petroleum diesel, and is a premium diesel with a high cetane number. As the first step in this research, two molybdenum catalysts were prepared, characterized and tested in a small-scale reactor. These catalysts were found to produce small amounts of benzene and cyclohexanol in the product stream, and confirmed the activity of the catalyst. A commercial cobalt molybdenum catalyst (Harshaw HT-400) was also tested and benzene, cyclohexanol, and cyclohexane were identified as products. Future work aims to synthesize catalysts to produce a high yield of cyclohexane. Once the conditions are optimized, we will do tests with biodiesel

A Summary of the Pioneer 10 Maneuver Strategy

The Pioneer Project placed a number of interesting and precise requirements on the navigation of the Pioneer 10 spacecraft flyby mission to Jupiter during 1972-1973. To satisfy these requirements the Pioneer navigation team employed a number of versatile computer programs to evaluate the strategies and maneuver sequences required to execute midcourse corrections. The Pioneer 10 mission objectives and the midcourse strategies used to satisfy these objectives are summarized

Reweighting of the form factors in exclusive B --> X ell nu decays

A form factor reweighting technique has been elaborated to permit relatively easy comparisons between different form factor models applied to exclusive B --> X l nu decays. The software tool developped for this purpose is described. It can be used with any event generator, three of which were used in this work: ISGW2, PHSP and FLATQ2, a new powerful generator. The software tool allows an easy and reliable implementation of any form factor model. The tool has been fully validated with the ISGW2 form factor hypothesis. The results of our present studies indicate that the combined use of the FLATQ2 generator and the form factor reweighting tool should play a very important role in future exclusive |Vub| measurements, with largely reduced errors.Comment: accepted for publication by EPJ

Formulas establish audio range inductance in beryllium coils

Mathematical modeling is used to determine the effects of resistance and capacitance upon the audio-inductance range of beryllium hammer coils and beryllium nylon-potted coils

Incompatible sets of gradients and metastability

We give a mathematical analysis of a concept of metastability induced by incompatibility. The physical setting is a single parent phase, just about to undergo transformation to a product phase of lower energy density. Under certain conditions of incompatibility of the energy wells of this energy density, we show that the parent phase is metastable in a strong sense, namely it is a local minimizer of the free energy in an $L^1$ neighbourhood of its deformation. The reason behind this result is that, due to the incompatibility of the energy wells, a small nucleus of the product phase is necessarily accompanied by a stressed transition layer whose energetic cost exceeds the energy lowering capacity of the nucleus. We define and characterize incompatible sets of matrices, in terms of which the transition layer estimate at the heart of the proof of metastability is expressed. Finally we discuss connections with experiment and place this concept of metastability in the wider context of recent theoretical and experimental research on metastability and hysteresis.Comment: Archive for Rational Mechanics and Analysis, to appea

Constraining differential rotation of Sun-like stars from asteroseismic and starspot rotation periods

In previous work we identified six Sun-like stars observed by Kepler with exceptionally clear asteroseismic signatures of rotation. Here, we show that five of these stars exhibit surface variability suitable for measuring rotation. In order to further constrain differential rotation, we compare the rotation periods obtained from light-curve variability with those from asteroseismology. The two rotation measurement methods are found to agree within uncertainties, suggesting that radial differential rotation is weak, as is the case for the Sun. Furthermore, we find significant discrepancies between ages from asteroseismology and from three different gyrochronology relations, implying that stellar age estimation is problematic even for Sun-like stars.Comment: Accepted for publication in A&A. 5 pages, 4 figure

The Three R\u27s: Reading, Riting, and Radio!

The radio presentation is a communication vehicle that provides input to our reading programs through the use of pupil-teacher initiated audio taped presentation, commercially prepared transcriptions and through local and network originated radio broadcasts

Light-cone sum rules for B→πB \to \pi form factors revisited

We reconsider and update the QCD light-cone sum rules for $B\to \pi$ form factors. The gluon radiative corrections to the twist-2 and twist-3 terms in the correlation functions are calculated. The $\bar{MS}$ $b$-quark mass is employed, instead of the one-loop pole mass used in the previous analyses. The light-cone sum rule for $f^+_{B\pi}(q^2)$ is fitted to the measured $q^2$-distribution in $B\to \pi l \nu_l$, fixing the input parameters with the largest uncertainty: the Gegenbauer moments of the pion distribution amplitude. For the $B\to \pi$ vector form factor at zero momentum transfer we predict $f^+_{B\pi}(0)= 0.26^{+0.04}_{-0.03}$. Combining it with the value of the product $|V_{ub}f^+_{B\pi}(0)|$ extracted from experiment, we obtain $|V_{ub}|=(3.5\pm 0.4\pm 0.2\pm 0.1) \times 10^{-3}$. In addition, the scalar and penguin $B\to \pi$ form factors $f^0_{B\pi}(q^2)$ and $f^T_{B\pi}(q^2)$ are calculated.Comment: 33 pages, 7 figures, one figure and a few comments added, version to appear in JHE

Estimated Surface Motions of the Earth's Core

Estimated surface fluid motions of earth core, and rotational and irrotational flow dat