<i>Aloe succotrina</i> (Asphodelaceae)

Aloe succotrina has a very long and complex taxonomic and nomenclatural history with wrong synonymy that is rivalled by few other aloes. This is mostly due to early authors wrongly assuming that this plant is from the Island of Socotra (Reynolds 1950). It has been in cultivation in Europe for over three hundred years, so consequently it is rather surprising that this iconic fynbos species has not featured in this journal until now

Effect of weak disorder on the ground state of uniaxial dipolar spin systems in the upper critical dimension

Extensive Monte Carlo simulations are used to investigate the stability of the ferromagnetic ground state in three-dimensional systems of Ising dipoles with added quenched disorder. These systems model the collective ferromagnetic order observed in various systems with dipolar long-range interactions. The uniaxial dipolar spins are arranged on a face-centred cubic lattice with periodic boundary conditions. Finite-size scaling relations for the pure dipolar ferromagnetic system are derived by a renormalisation group calculation. These functions include logarithmic corrections to the expected mean field behaviour since the system is in its upper critical dimension. Scaled data confirm the validity of the finite-size scaling description and results are compared with subsequent analysis of weakly disordered systems. A disorder-temperature phase diagram displays the preservation of the ferromagnetic ground state with the addition of small amounts of disorder, suggesting the irrelevance of weak disorder in these systems.Comment: 6 pages, 4 figures; proceedings of the 3rd NEXT-Sigma-Phi Conference, Kolymbari, Greece, August 200

Significance of literature when constructing a theory: a selective literature review

The issues around use of literature in theory construction are often a source of confusion, especially for novice researchers. The very nature of the process of theory construction remains blurred due to lack of consensus among researchers. Novice researchers are often confronted with questions of whether or not a literature review should be conducted when constructing a theory. These questions seeking to justify what a credible methodology is when constructing a theory not only challenge novice researchers but also experienced researchers. This article explores different perspectives regarding the significance of literature review in theory construction. A selective literature review was used to access and interrogate selected arguments from published peer-reviewed work. Narrative analysis was used to analyse selected text. It is concluded that literature plays a pivotal role in theory construction, whether by active review in the case of novice researchers or being sensitised by virtue of discipline interest and prolonged exposure in experienced researchers. However, it is important not to disregard the view that it is not necessary to incorporate literature review in certain specific designs due to assumed influence on the outcome of the new theory.Department of HE and Training approved lis

Green IS Management Framework Corroboration and Verification: Explicating the Enabling Capabilities of Green IS

The first objective of the paper is to demonstrate the quantitative corroboration of the Green Information Systems (Green IS) management framework, which comprises the enabling capabilities of Green IS, the moderating concepts, and their relationships to environmental sustainability. The second objective is to demonstrate the framework’s verification using the focus group method and member checking. The achievement of these objectives establishes that the framework successfully captured the essential Green IS concepts and interrelationships to be relevant for environmental sustainability, that it was credible, relevant, and an original contribution to the academic body of knowledge. The research was empirical, confirmatory, quantitative, and qualitative. The study provides research design insights by detailing research design choices and rationale. The framework presents verified and salient management focal points for environmental sustainability in the South African banking sector

Combination PPARγ and RXR Agonist Treatment in Melanoma Cells: Functional Importance of S100A2

Nuclear hormone receptors, including RXR and PPARγ, represent novel therapeutic targets in melanoma. We have previously shown that the DRO subline of the amelanotic melanoma A375 responds to rexinoid and thiazolidinedione (TZD) treatment in vitro and in vivo. We performed microarray analysis of A375(DRO) after TZD and combination rexinoid/TZD treatment in which the calcium binding protein S100A2 had increased expression after rexinoid or TZD treatment and a synergistic increase to combination treatment. Increased S100A2 expression is dependent on an intact PPARγ receptor, but it is not sufficient to mediate the antiproliferative effects of rexinoid/TZD treatment. Over expression of S100A2 enhanced the effect of rexinoid and TZD treatment while inhibition of S100A2 expression attenuated the response to rexinoid/TZD treatment, suggesting that S100A2 is necessary for optimal response to RXR and PPARγ activation by respective ligands. In summary, we have identified potential downstream mediators of rexinoid and TZD treatment in a poorly differentiated melanoma and found that alterations in S100A2 expression affect RXR and PPARγ signaling in A375(DRO) cells. These studies provide insight into potential mechanisms of tumor response or resistance to these novel therapies

Recircumscription and distribution of elements of the ‘Ceterach cordatum’ complex (Asplenium: Aspleniaceae) in southern Africa

Ceterachoid aspleniums in southern Africa have long been treated as a single widespread and variable taxon, Asplenium cordatum (Thunb.) Sw. (= Ceterach cordatum Thunb.). In addition to A. cordatum, a further two ceterachoid taxa are now recognized as occurring in the Flora of southern Africa (FSA) region, namely A. capense (Kunze) Bir, Fraser-Jenk. & Lovis and A. phillipsianum (Kümmerle) Bir, Fraser-Jenk. & Lovis. We provide full descriptions and distributions of these three taxa.http://www.sanbi.org/products/publications/bothalia.ht

A revised generic classification for <em>Aloe</em> (Xanthorrhoeaceae subfam. Asphodeloideae)

Grace, Olwen M., Klopper, Ronell R., Smith, Gideon F., Crouch, Neil R., Figueiredo, Estrela, Rønsted, Nina, Van Wyk, Abraham E. (2013): A revised generic classification for Aloe (Xanthorrhoeaceae subfam. Asphodeloideae). Phytotaxa 76 (1): 7-14, DOI: 10.11646/phytotaxa.76.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.76.1.

Tensor Product Approximation (DMRG) and Coupled Cluster method in Quantum Chemistry

We present the Copupled Cluster (CC) method and the Density matrix Renormalization Grooup (DMRG) method in a unified way, from the perspective of recent developments in tensor product approximation. We present an introduction into recently developed hierarchical tensor representations, in particular tensor trains which are matrix product states in physics language. The discrete equations of full CI approximation applied to the electronic Schr\"odinger equation is casted into a tensorial framework in form of the second quantization. A further approximation is performed afterwards by tensor approximation within a hierarchical format or equivalently a tree tensor network. We establish the (differential) geometry of low rank hierarchical tensors and apply the Driac Frenkel principle to reduce the original high-dimensional problem to low dimensions. The DMRG algorithm is established as an optimization method in this format with alternating directional search. We briefly introduce the CC method and refer to our theoretical results. We compare this approach in the present discrete formulation with the CC method and its underlying exponential parametrization.Comment: 15 pages, 3 figure

Aloiampelos ciliaris var. ciliaris. Asphodelaceae: Alooideae

Aloiampelos ciliaris is the type of a new genus of just seven species separated from Aloe in 2013 to accommodate the scrambling South African aloes. The history, taxonomy, distribution, ecology, cytology and cultivation of this species are all discussed in detail. This species is unique for Southern Africa in having a hexaploid chromosome count of 2n=42. The leaf structure is also distinctive with an amplexicaul base bearing conspicuous white cilia. It is endemic to the Eastern Cape Province