The root morphology of some legume spp. in the south-western Cape and the relationship of vesicular-arbuscular mycorrhizas with dry mass and phosphorus content of Acacia saligna seedlings

The root systems of Acacia saligna (Labill.) Wendl. have more extensive laterals than those examples of the Fabaceae indigenous to the Cape. Aspalathus flexuosa Thunb. and Rafnia angulata Thunb. had lateral roots infected with vesicular-arbuscular (VA) mycorrhizal fungi whereas those of Aspalathus albens L. were non-mycorrhizal. VA mycorrhizal fungi were found in the roots of seedlings of A. saligna. Chlamydospores of the genus Glomus and three types of Gigaspora auxiliary cells were identified. VA mycorrhizal colonization was correlated with the dry mass and phosphorus content of A. saligna seedlings. Seedling dry mass, phosphorus content, nodule production and VA mycorrhizal colonization decreased with increased sowing density. The more extensive root system and abundance of root nodules and VA mycorrhizas apparently contribute to the success of A. saligna as an invasive weed of the fynbos vegetation

Rigidity of minimal submanifolds in hyperbolic space

We prove that if an $n$-dimensional complete minimal submanifold $M$ in hyperbolic space has sufficiently small total scalar curvature then $M$ has only one end. We also prove that for such $M$ there exist no nontrivial $L^2$ harmonic 1-forms on $M$

Environmental change in Namibia: land-use impacts and climate change as revealed by repeat photography

This essay draws on repeat landscape photography to explore and juxtapose different cultural and scientific understandings of environmental change and sustainability in west Namibia. Change in the landscape ecology of western and central Namibia over the last 140 years has been investigated using archival landscape photographs located and re-photographed, or ‘matched’, with recent photographs. Each set of matched images for a site provides a powerful visual statement of change and/or stability that can assist with understanding present circumstances at specific places. The chapter shows in a practical way an innovative possibility for documenting and analysing environmental and social change, helping us to contextualise projected and predicted environmental futures, and sometimes offering complexity with regard to modelled climate change projections and scenarios

Land reform in Namaqualand: Poverty alleviation, stepping stones and economic units

This paper examines the consequences of land reform for communal livestock farmers in Namaqualand. It investigates the likely outcomes of recent commonage acquisitions and tenure reform in the former ëColoured Reservesí using case study material drawn from the Leliefontein communal area. In particular, we try to answer two questions about land reform in Namaqualand. The first is concerned with models of land management in both new and old common lands: what effect will the imposition of either a commercial or communal land management model have on twin objectives of poverty alleviation and environmental sustainability? We conclude that the commercial farming model is rarely appropriate in Namaqualandís communal areas and suggest that sustainable development is more likely under a flexible system which takes account of both the objectives of communal farmers and the constraints under which they operate. The second question explores the implications of recent policy shifts regarding the use of commonage as a ëstepping stoneí for emergent black commercial farmers. We ask if this is feasible in the Namaqualand context and conclude that present rates of grant are inadequate to provide incentives for emergent commercial farmers to move off the commons. The contradictions inherent in using the commons for both poverty alleviation and as a ëstepping stoneí are likely to result in a backward step reminiscent of the discredited ëeconomic unitsí policy

Assessment of patient-derived tumour xenografts (PDXs) as a discovery tool for cancer epigenomics

Background: The use of tumour xenografts is a well-established research tool in cancer genomics but has not yet been comprehensively evaluated for cancer epigenomics. Methods: In this study, we assessed the suitability of patient-derived tumour xenografts (PDXs) for methylome analysis using Infinium 450 K Beadchips and MeDIP-seq. Results: Controlled for confounding host (mouse) sequences, comparison of primary PDXs and matching patient tumours in a rare (osteosarcoma) and common (colon) cancer revealed that an average 2.7% of the assayed CpG sites undergo major (Δβ ≥ 0.51) methylation changes in a cancer-specific manner as a result of the xenografting procedure. No significant subsequent methylation changes were observed after a second round of xenografting between primary and secondary PDXs. Based on computational simulation using publically available methylation data, we additionally show that future studies comparing two groups of PDXs should use 15 or more samples in each group to minimise the impact of xenografting-associated changes in methylation on comparison results. Conclusions: Our results from rare and common cancers indicate that PDXs are a suitable discovery tool for cancer epigenomics and we provide guidance on how to overcome the observed limitations

Cosmology with Hypervelocity Stars

In the standard cosmological model, the merger remnant of the Milky Way and Andromeda (Milkomeda) will be the only galaxy remaining within our event horizon once the Universe has aged by another factor of ten, ~10^{11} years after the Big Bang. After that time, the only extragalactic sources of light in the observable cosmic volume will be hypervelocity stars being ejected continuously from Milkomeda. Spectroscopic detection of the velocity-distance relation or the evolution in the Doppler shifts of these stars will allow a precise measurement of the vacuum mass density as well as the local matter distribution. Already in the near future, the next generation of large telescopes will allow photometric detection of individual stars out to the edge of the Local Group, and may target the ~10^{5+-1} hypervelocity stars that originated in it as cosmological tracers.Comment: 4 pages, 2 figures, accepted for publication in the Journal of Cosmology and Astroparticle Physics (JCAP, 2011

Chemostratigraphy of Neoproterozoic carbonates: implications for 'blind dating'

The delta C-13(carb) and Sr-87/Sr-86 secular variations in Neoproteozoic seawater have been used for the purpose of 'isotope stratigraphy' but there are a number of problems that can preclude its routine use. In particular, it cannot be used with confidence for 'blind dating'. The compilation of isotopic data on carbonate rocks reveals a high level of inconsistency between various carbon isotope age curves constructed for Neoproteozoic seawater, caused by a relatively high frequency of both global and local delta C-13(carb) fluctuations combined with few reliable age determinations. Further complication is caused by the unresolved problem as to whether two or four glaciations, and associated negative delta C-13(carb) excursions, can be reliably documented. Carbon isotope stratigraphy cannot be used alone for geological correlation and 'blind dating'. Strontium isotope stratigraphy is a more reliable and precise tool for stratigraphic correlations and indirect age determinations. Combining strontium and carbon isotope stratigraphy, several discrete ages within the 590-544 Myr interval, and two age-groups at 660-610 and 740-690 Myr can be resolved

Isolation, characterisation, and selection of wine yeast strains in Etyek-Buda wine district, Hungary

Initiated by the Association “Wine Route of Etyek Wine District”, the objectives of this study were to isolate and identify autochthonous yeast strains from local wines and to determine their oenologically important properties. The first aim of this work was to characterize the taxonomic and phenotypic diversity of the representative Saccharomyces yeast strains that dominate the spontaneous fermentations in this wine district. The results obtained by molecular ribotyping (ARDRA) revealed a strong dominance of S. cerevisiae, but S. bayanus var. uvarum was also present sporadically. Some of the natural isolates exhibited high volatile acid production or poor fermentation capacity, which imply a quality risk in spontaneous fermentations. Most of the isolates, however, displayed good oenological features during lab scale fermentations. As the second aim of this work, the most promising, selected strains were further tested for oenological properties in microvinification scale and, finally, in large scale fermentations. The analytical and sensory analysis proved that selected strains, including S. bayanus var. uvarum, can be used as local starter cultures, which may contribute to the typicality of the local wines in comparison with commercial starters