University of Adelaide

About: University of Adelaide is a education organization based out in Adelaide, South Australia, Australia. It is known for research contribution in the topics: Population & Pregnancy. The organization has 27251 authors who have published 79167 publications receiving 2671128 citations. The organization is also known as: The University of Adelaide & Adelaide University.

Soft core hyperon - nucleon potentials

Abstract: A new Nijmegen soft-core OBE potential model is presented for the low-energy $\mathrm{YN}$ interactions. Besides the results for the fit to the scattering data, which largely defines the model, we also present some applications to hypernuclear systems using the G-matrix method. The potentials are generated by the exchange of nonets of pseudoscalar, vector, and scalar mesons. As is standard in the Nijmegen soft-core models, we also include the $J=0$ contributions from the tensor ${f}_{2}{,f}_{2}^{\ensuremath{'}}{,a}_{2},$ and pomeron Regge trajectories, and use Gaussian form factors to guarantee that the potentials have a soft behavior near the origin. An important innovation with respect to the original soft-core potential is the assignment of the cutoff masses for the baryon-baryon-meson (BBM) vertices in accordance with broken $\mathrm{SU}{(3)}_{F},$ which serves to connect the $\mathrm{NN}$ and the $\mathrm{YN}$ channels. As a novel feature, we allow for medium strong breaking of the coupling constants, using the ${}^{3}{P}_{0}$ model with a Gell-Mann--Okubo hypercharge breaking for the BBM coupling. Charge-symmetry breaking in the $\ensuremath{\Lambda}p$ and $\ensuremath{\Lambda}n$ channels is included as well. We present six hyperon-nucleon potentials which describe the available $\mathrm{YN}$ cross section data equally well, but which exhibit some differences on a more detailed level. The differences are constructed such that the models encompass a range of scattering lengths in the $\ensuremath{\Sigma}N$ and $\ensuremath{\Lambda}N$ channels. In all cases, we obtained ${\ensuremath{\chi}}^{2}{/N}_{\mathrm{data}}\ensuremath{\approx}0.55$ for 35 $\mathrm{YN}$ data. In particular, we were able to fit the precise experimental datum ${r}_{R}=0.468\ifmmode\pm\else\textpm\fi{}0.010$ for the inelastic capture ratio at rest. For the scalar-meson mixing angle we obtained values ${\ensuremath{\theta}}_{S}=37\ifmmode^\circ\else\textdegree\fi{}--40\ifmmode^\circ\else\textdegree\fi{},$ which points to almost ideal mixing angles for the scalar $q\overline{q}$ states. The G-matrix results indicate that the remarkably different spin-spin terms of the six potentials appear specifically in the energy spectra of $\ensuremath{\Lambda}$ hypernuclei.

Plant performance in stressful environments: interpreting new and established knowledge of the roles of arbuscular mycorrhizas

Abstract: Arbuscular mycorrhizal (AM) symbioses are formed by approximately 80% of vascular plant species in all major terrestrial biomes. In consequence an understanding of their functions is critical in any study of sustainable agricultural or natural ecosystems. Here we discuss the implications of recent results and ideas on AM symbioses that are likely to be of particular significance for plants dealing with abiotic stresses such as nutrient deficiency and especially water stress. In order to ensure balanced coverage, we also include brief consideration of the ways in which AM fungi may influence soil structure, carbon deposition in soil and interactions with the soil microbial and animal populations, as well as plant-plant competition. These interlinked outcomes of AM symbioses go well beyond effects in increasing nutrient uptake that are commonly discussed and all require to be taken into consideration in future work designed to understand the complex and multifaceted responses of plants to abiotic and biotic stresses in agricultural and natural environments.

The genomic history of southeastern Europe

Abstract: Farming was first introduced to Europe in the mid-seventh millennium bc, and was associated with migrants from Anatolia who settled in the southeast before spreading throughout Europe. Here, to und ...