Quantum Gravity coupled to Matter via Noncommutative Geometry

We show that the principal part of the Dirac Hamiltonian in 3+1 dimensions emerges in a semi-classical approximation from a construction which encodes the kinematics of quantum gravity. The construction is a spectral triple over a configuration space of connections. It involves an algebra of holonomy loops represented as bounded operators on a separable Hilbert space and a Dirac type operator. Semi-classical states, which involve an averaging over points at which the product between loops is defined, are constructed and it is shown that the Dirac Hamiltonian emerges as the expectation value of the Dirac type operator on these states in a semi-classical approximation.Comment: 15 pages, 1 figur

Genetic Family and Stock Type Influence Simulated Loblolly Pine Yields from Wet Sites

Planting adapted families or a bulked seedlot of bare-root and container-grown-seedlings of loblolly pine (Pinus taeda L) were contrasted as cost effective alternatives for regenerating Arkansas\u27 wet sites. Survival data from two wet sites were used to simulate 15 years of growth. Containerized seedlings provided 17% greater survival than bare-root seedlings, but yielded a lower present net worth than bare-root seedlings. Planting families adapted to excessive moisture provided 7% greater survival and yielded a greater present net worth than planting a bulked seedlot consisting of adapted and poorly adapted families

Ex post facto authorisation in South African environmental assessment legislation: a critical review

One of the fundamental tenets underlying environmental assessment both internationally and in South Africa is that it is anticipatory in nature in that it is essentially an evaluation of the effects likely to arise from a major project or other action significantly affecting the natural or artificial environment. Environmental impact assessment (EIA) is therefore a systematic and integrative process for considering possible impacts prior to a decision being taken on whether or not a proposal should be given approval to proceed. This article argues that the current legislative basis for environmental assessment in South Africa, namely Part V of the Environment Conservation Act 73 of 1998 (ECA) and regulations made under it, reflects this philosophy. It argues that the phenomenon of ex post facto or retrospective environmental authorisation is ultra vires and thus not permissible under the current legislative regime. Finally the article outlines and assesses the environmental assessment regime under the National Environmental Management Act 107 of 1998 (NEMA) and recent amendments to it under the NEMA Amendment Act 8 of 2004, which will in future govern the environmental assessment process. The amending Act introduces a new section 24G into the anticipated environmental assessment regime which will permit ex post facto or retrospective environmental authorisation. The authors argue that this is an unwelcome development which will militate against the purposes underlying environmental assessment

Ex post facto authorisation in south african environmental assessment legislation: A critical review

One of the fundamental tenets underlying environmental assessment both internationally and in South Africa is that it is anticipatory in nature in that it is essentially an evaluation of the effects likely to arise from a major project or other action significantly affecting the natural or artificial environment. Environmental impact assessment (EIA) is therefore a systematic and integrative process for considering possible impacts prior to a decision being taken on whether or not a proposal should be given approval to proceed. This article argues that the current legislative basis for environmental assessment in South Africa, namely Part V of the Environment Conservation Act 73 of 1998 (ECA) and regulations made under it, reflects this philosophy. It argues that the phenomenon of ex post facto or retrospective environmental authorisation is ultra vires and thus not permissible under the current legislative regime. Finally the article outlines and assesses the environmental assessment regime under the National Environmental Management Act 107 of 1998 (NEMA) and recent amendments to it under the NEMA Amendment Act 8 of 2004, which will in future govern the environmental assessment process. The amending Act introduces a new section 24G into the anticipated environmental assessment regime which will permit ex post facto or retrospective environmental  authorisation. The authors argue that this is an unwelcome development which will militate against the purposes underlying environmental assessment

Attentional modulation of orthographic neighborhood effects during reading: Evidence from event-related brain potentials in a psychological refractory period paradigm

It is often assumed that word reading proceeds automatically. Here, we tested this assumption by recording event-related potentials during a psychological refractory period (PRP) paradigm, requiring lexical decisions about written words. Specifically, we selected words differing in their orthographic neighborhood size–the number of words that can be obtained from a target by exchanging a single letter–and investigated how influences of this variable depend on the availability of central attention. As expected, when attentional resources for lexical decisions were unconstrained, words with many orthographic neighbors elicited larger N400 amplitudes than those with few neighbors. However, under conditions of high temporal overlap with a high priority primary task, the N400 effect was not statistically different from zero. This finding indicates strong attentional influences on processes sensitive to orthographic neighbors during word reading, providing novel evidence against the full automaticity of processes involved in word reading. Furthermore, in conjunction with the observation of an underadditive interaction between stimulus onset asynchrony (SOA) and orthographic neighborhood size in lexical decision performance, commonly taken to indicate automaticity, our results raise issues concerning the standard logic of cognitive slack in the PRP paradigm

Quasi-Dirac Operators and Quasi-Fermions

We investigate examples of quasi-spectral triples over two-dimensional commutative sphere, which are obtained by modifying the order-one condition. We find equivariant quasi-Dirac operators and prove that they are in a topologically distinct sector than the standard Dirac operator.Comment: 11 page

Adaptive IT capability and its impact on the competitiveness of firms: a dynamic capability perspective

The link between information technology (IT) and competitive advantage has been the preoccupation of many IT researchers. IT plays a key role as a necessary, but not sufficient, source of value. Prior research has in most cases investigated the direct link between IT and competitive advantage. Other researchers have examined the effect of IT on mediating factors (such as firm strategy) or applied higher order IT support for core competences in their research constructs. Only a few have recognised the potential of IT in enabling dynamic capabilities. This thesis argues that the dynamic capability perspective of strategic management provides a better insight into how IT, beyond its traditional role, needs to be converted into a higher order resource to deliver competitive advantage. The objectives of the study are therefore: (1) to apply the concept of the dynamic capability perspective to the IT-competitive advantage research in order to explicate the strategic role of IT in attaining competitive advantage; and (2) to examine the antecedent capabilities and competences that may lead towards developing adaptive IT capability. This study proposes and empirically tests a dynamic capability-based model of IT and competitive advantage. The proposed model posits adaptive IT capability as a mediating higher order resource that relies on IT capabilities (infrastructure, personnel and management) and IT support for core competences (operational and market) to influence a firm's competitive position (competitive edge in market and financial performance). The model also hypothesises that IT support for core competences can lead to competitive advantages. To test the model, data were collected from a cross- sectional sample of 203 medium- and large-sized Australian organisations. Descriptive and analytical (structural equation modelling) tools were employed to test both the measurement and structural models. The findings reveal that the developed model explained 28% of the variance in competitive advantage, 72% for adaptive IT capability, 51% for IT support for operational and market competence, demonstrating the strategic role of adaptive IT capabilities as sources of competitive advantage. This indicates that those firms that deploy IT for creating operational and market competences require a further capacity to rebuild and reconfigure their resources to improve market and financial performance. Thus, it appears that the impact of IT support for core competences on competitive advantage is not direct, but indirect through adaptive IT capability. Several IT capabilities and competences were identified as antecedents for building adaptive IT capabilities. This PhD study's main contribution lies in bridging a research gap by developing and empirically testing a model of adaptive IT capability that measures how IT can enable firms' dynamic capabilities. The model includes both the antecedent factors that build the higher order resource of adaptive IT capability (upstream factors) as well as the effect on competitive advantage (downstream factors). Practitioners can benefit from the results of this study in terms of the ramifications for investment decisions as well as to benchmark where they stand with their IT in terms of potential for value creation and business support

Spin Foams and Noncommutative Geometry

We extend the formalism of embedded spin networks and spin foams to include topological data that encode the underlying three-manifold or four-manifold as a branched cover. These data are expressed as monodromies, in a way similar to the encoding of the gravitational field via holonomies. We then describe convolution algebras of spin networks and spin foams, based on the different ways in which the same topology can be realized as a branched covering via covering moves, and on possible composition operations on spin foams. We illustrate the case of the groupoid algebra of the equivalence relation determined by covering moves and a 2-semigroupoid algebra arising from a 2-category of spin foams with composition operations corresponding to a fibered product of the branched coverings and the gluing of cobordisms. The spin foam amplitudes then give rise to dynamical flows on these algebras, and the existence of low temperature equilibrium states of Gibbs form is related to questions on the existence of topological invariants of embedded graphs and embedded two-complexes with given properties. We end by sketching a possible approach to combining the spin network and spin foam formalism with matter within the framework of spectral triples in noncommutative geometry.Comment: 48 pages LaTeX, 30 PDF figure

On Semi-Classical States of Quantum Gravity and Noncommutative Geometry

We construct normalizable, semi-classical states for the previously proposed model of quantum gravity which is formulated as a spectral triple over holonomy loops. The semi-classical limit of the spectral triple gives the Dirac Hamiltonian in 3+1 dimensions. Also, time-independent lapse and shift fields emerge from the semi-classical states. Our analysis shows that the model might contain fermionic matter degrees of freedom. The semi-classical analysis presented in this paper does away with most of the ambiguities found in the initial semi-finite spectral triple construction. The cubic lattices play the role of a coordinate system and a divergent sequence of free parameters found in the Dirac type operator is identified as a certain inverse infinitesimal volume element.Comment: 31 pages, 10 figure

Ex post facto authorisation in South African environmental assessment legislation: a critical review

One of the fundamental tenets underlying environmental assessment both internationally and in South Africa is that it is anticipatory in nature in that it is essentially an evaluation of the effects likely to arise from a major project or other action significantly affecting the natural or artificial environment. Environmental impact assessment (EIA) is therefore a systematic and integrative process for considering possible impacts prior to a decision being taken on whether or not a proposal should be given approval to proceed.  This article argues that the current legislative basis for environmental assessment in South Africa, namely Part V of the Environment Conservation Act 73 of 1998 (ECA) and regulations made under it, reflects this philosophy. It argues that the phenomenon of ex post facto or retrospective environmental authorisation is ultra vires and thus not permissible under the current legislative regime.  Finally the article outlines and assesses the environmental assessment regime under the National Environmental Management Act 107 of 1998 (NEMA) and recent amendments to it under the NEMA Amendment Act 8 of 2004, which will in future govern the environmental assessment process. The amending Act introduces a new section 24G into the anticipated environmental assessment regime which will permit ex post facto or retrospective environmental authorisation. The authors argue that this is an unwelcome development which will militate against the purposes underlying environmental assessment.   &nbsp