Polarization observables in the e+e−→ΛˉΛe^+ e^- \rightarrow \bar{\Lambda} \Lambda reaction

Cross-section, vector-polarization, and tensor-polarization distributions are calculated for the reactions $e^+ e^- \rightarrow \bar{p}p$ and $e^+ e^- \rightarrow \bar{\Lambda} \Lambda$. Each reaction requires six characteristic functions that are bilinear in the, possibly complex, electromagnetic form factors, denoted $G_E(P^2)$ and $G_M(P^2)$, of $p$ and $\Lambda$. For the hyperon reaction also the joint-decay distributions of $\Lambda$ and $\bar{\Lambda}$ are calculated. Their knowledge allow a complete determination of the hyperon electromagnetic form factors, without measuring hyperon spins. We explain how this is done in practice. For some tensor-polarization components our results are in conflict with previously repeatedly published distributions.Comment: 17 page

Doing Events Research: From Theory to Practice

A review of the book, entitled "Doing Events Research: From Theory to Practice

Research Methods: A Practical Guide for Students and Researchers

Willie Tan Research Methods: A Practical Guide for Students and Researchers World Scientific Publishing, Singapore, 2017 ISBN: 978-981-3229-58-7 (hardcover), ISBN: 978-981-3229-61-7 (softcover). 228 page

Cultural Pluralism and Epistemic Injustice

For liberalism, values such as respect, reciprocity, and tolerance should frame cultural encounters in multicultural societies. However, it is easy to disregard that power differences and political domination also influence the cultural sphere and the relations between cultural groups. In this essay, I focus on some challenges for cultural pluralism. In relation to Indian political theorist Rajeev Bhargava, I discuss the meaning of cultural domination and epistemic injustice and their historical and moral implications. Bhargava argued that as a consequence of colonialism, “indigenous cultures” were inferiorized, marginalized, and anonymized. Although cultures are often changing due to external influences, I argue that epistemic injustice implies that a culture is forced to subjection, disrespected, and considered as inferior and that it threatens the dominated people’s epistemic framework, collective identity, and existential security. Finally, I refer to John Rawls’s theory of political liberalism as a constructive approach to avoid parochialism and Western cultural dominatio

Plant analysis as a tool to determine crop nitrogen status

An effective plant nutrient management strategy optimises nitrogen (N) use efficiency for minimised environmental impact, while ensuring an optimum N status of the crop for good product quality and maximum growth. Soil or plant analysis can be used to evaluate the strategy; however the use of plant analysis for this purpose has been limited. One reason is lack of reliable reference values for the critical concentration needed for optimal growth. This study builds on theories that relate ontogenetic changes in the critical N concentration to changes in the relation between mass and surface area of the entire plant and of individual leaves. Through the establishment of critical N concentrations on the basis of these theories, some of the drawbacks hitherto experienced with plant analysis, such as difficulties in defining growth stage or plant part to sample, can be avoided. The aim of this thesis was to establish critical N concentrations for white cabbage (Brassica oleracea L. var. capitata L. f. alba D.C.) on the basis of these theories. Multi-N-rate and multi-harvest experiments were conducted in the field and in a climate chamber. The results showed that the critical N concentration declined at the same rate (-0.33) as the plant's leaf area ratio (leaf area divided by plant mass), which is in agreement with the 2/3-Power rule or "skin-core" hypothesis. The critical N concentration (% of DM) on a whole plant basis was estimated to 4.5 (W1.5 t ha-1), where W is weight per unit area of plant dry matter exclusive of roots. Moreover, it was concluded that the unshaded horizontally orientated leaves of cabbage can be used for leaf area based plant analysis of individual leaves. The critical N concentration of these leaves expressed on an area basis was found to be 3.7 g N m-2, while that for the whole plant N on a leaf area basis was 4.7 g N m-2. The ratio of these two critical concentrations, 0.8, was similar to the leaf N ratio (leaf N/whole plant N) of young plants before self shading occurs

Perennial clovers and ryegrasses as understorey crops in cereals

Perennial crops undersown in cereals provide ground cover from harvest of the cereal crop to sowing of the next crop. Such cover crops can e.g. reduce soil erosion, nutrient leaching and N fertiliser requirements of the succeeding crop. The objective of this thesis was to develop guidelines on how to prevent grain yield losses due to competition from the perennial crops or to increase the yield of the main crops. The effects of species and time of undersowing of perennial crops in spring cereals, and the management of an intercropping system in which winter oilseed rape or consecutive crops of winter wheat were established in a remaining crop of white clover, were studied. The biomass of undersown cover crops by the time of the harvest of spring barley was significantly reduced with each delay in the undersowing, but the increase in biomass during autumn was generally not affected. Italian ryegrass (Lolium multiflorum Lam) and perennial ryegrass (Lolium perenne L.) reduced the grain yield by 6 and 1%, respectively, but may both be suitable as cover crops with the appropriate main crop, time of undersowing and seed rate. Undersown white clover (Trifolium repens L.)/perennial ryegrass mixtures kept soil mineral N as low as pure ryegrass and improved the residual effect. This suggests that clover in the cover crops may reduce the N fertiliser requirements of the succeeding crop without increased N leaching. Grain yields were smaller in the wheat/clover system than with wheat alone when the wheat was direct drilled and larger when sown after stubble cultivation. Direct drilled wheat and rape yielded more with clover varieties less adapted to the cold climate than with varieties in common use in the area. Grain yield increased, weeds were efficiently controlled and the white clover crop maintained by applying herbicides that mainly act as germination inhibitors when a third consecutive wheat crop had 1–2 leaves. It was possible to conclude that (1) the tillage performed in conjunction with the sowing of wheat, (2) the weed control practice, and (3) the choice of clover variety, have large effects on the yield of the winter annuals in the intercropping system