Modelling the impacts of the industrial biofuels strategy on the South African agricultural and biofuel subsectors

The potential impact of the current South African industrial biofuels strategy on the economic feasibility of biofuel production in South Africa is analysed and discussed. The analysis is then taken a step further by means of a scenario to analyse the potential impacts of higher global prices on the feasibility of a local biofuel industry. The BFAP sector model, a partial equilibrium model, is used to simulate the various impacts over the period 2009 to 2017. This study shows that the incentives and commitments, as presented through the strategy, are not sufficient to get a local biofuel industry up and running and make it sustainable in the long term.Resource /Energy Economics and Policy,

Expression of the CD6 T lymphocyte differentiation antigen in normal human brain

Antigens shared by the immune and central nervous systems (CNS) have been described repeatedly. The present study reports the expression of the CD6 lymphocyte differentiation antigen in normal human brain evidenced by immunohistochemistry and Northern blot analysis. A panel of various anti-CD6 monoclonal antibodies (mabs) tested on serial cryostat sections identified CD6-positive cells randomly scattered in parenchyma of all examined brain areas. Northern blot analysis with a highly sensitive cRNA probe revealed a 3.1 kb CD6-specific mRNA in various brain regions, especially in basalganglia and cortex cerebellum. Staining with mabs raised against different hematopoietic cell types, as well as hybridization with probes specific for the ß- and y-T cell receptor (TCR) chains support the notion that CD6 is expressed by original brain cells. The nature of the CD6-positive cell type and possible functions of shared antigens in immune and nervous systems are discusse

THE CELLULAR RECEPTOR (CD4) OF THE HUMAN IMMUNODEFICIENCY VIRUS IS EXPRESSED ON NEURONS AND GLIAL CELLS IN HUMAN BRAIN

The peculiar tropism of the human immunodeficiency virus (HIV) for T helper lymphocytes can be explained by a specific interaction between the virus and the CD4 molecule on these cells (1, 2). The tropism for T lymphocytes, however, can hardly account for the early brain infection observed in some AIDS (acquired immune deficiency syndrome) patients (3, 4). Since CD4 is also expressed on virus-susceptible non-T cell lines we wondered whether an additional expression site of CD4 could be demonstrated in neural tissue (5). To this end, CD4 expression in brain was analyzed with several different anti-CD4 mAbs, and using a CD4-specific cDNA probe in Northern blot analyses . CD4' cells and CD4-specific mRNA were found in the cerebellum, thalamus, and pons. The reactive cells could be identified as neurons as well as glial cells

Knowledge-based Model Building with KONWERK

Modeling a real world optimization problem in a form which can be processed by a machine (computer) is usually a very difficult and complex task. Therefore, building and verifying the model is often the most time consuming part of the whole process of solving a real world problem using methods of Operations Research. Software tools, which integrate representation methods developed in the field of Artificial Intelligence (AI) and methods of OR, can facilitate and speed up the process of model development. The paper introduces the idea of knowledge based modeling as a model development and representation technique facilitating the complex process of model building. We describe the KONWERK tool-box which combines hierarchical structured knowledge representation and object oriented methodology thus providing a framework for model building and application of different optimization methods. We want the reader to form an idea of the methodology of model development and knowledge representation with KONWERK and to understand the hierarchical structure of the knowledge base. The model of the Nitra River Case is used to describe and explain the modeling and knowledge representation with KONWERK. A given multicriteria model of the Nitra River Case was reimplemented using KONWERK within about three weeks and later enlarged by implementation of additional fairness criteria

Modelling the impacts of macro-economic variables on the South African biofuels industry

The production of biofuels from agricultural commodities has received much attention in recent years. Apart from a few private initiatives, biofuels have not seen a large scale, commercial production in South Africa to date. This article sketches a basic picture of the economic feasibility of biofuel production in South Africa, without any form of government support, at 2006 prices. It then takes the analysis a step further and with the aid of a set of scenarios, different potential outcomes, due to a range of possible policy implementation measures, are discussed and the results documented. The Bureau for Food and Agricultural Policy’s (BFAP) sector model is used to simulate the impact of various options on the potential biofuels industry and other related industries during the course of the 2007 to 2015 period. This study shows that a lack of government support for the local biofuels industry could seriously affect its economic viability, especially in the early stages of the industry’s development. Additional issues, such as the impact on food and feed prices, also need to be taken into consideration.Resource /Energy Economics and Policy,

Simple Lattice-Models of Ion Conduction: Counter Ion Model vs. Random Energy Model

The role of Coulomb interaction between the mobile particles in ionic conductors is still under debate. To clarify this aspect we perform Monte Carlo simulations on two simple lattice models (Counter Ion Model and Random Energy Model) which contain Coulomb interaction between the positively charged mobile particles, moving on a static disordered energy landscape. We find that the nature of static disorder plays an important role if one wishes to explore the impact of Coulomb interaction on the microscopic dynamics. This Coulomb type interaction impedes the dynamics in the Random Energy Model, but enhances dynamics in the Counter Ion Model in the relevant parameter range.Comment: To be published in Phys. Rev.

Climate change mitigation in aging societies: Motivational and cognitive aspects

The success of mitigating climate change depends on actions taken within the upcoming four decades. In Western societies, this timeframe coincides with a demographic shift increasing the age of the median voter and decision maker. The willingness to contribute to climate change mitigation may decrease with age since the benefi ts may lie beyond the life span whereas the costs are immediate. In several experimental studies, we investigate cognitive limitations and motivational factors in relation to climate change mitigation. In a fi rst set of studies subjects are given the chance to invest up to 10€ into the reduction of CO2 via the EU ETS. Contrary to theoretical considerations, we fi nd evidence for a strong and positive effect of age. Furthermore we show that social cues can be used to in uence contributions. Moreover we demonstrate that independent of age most subjects are able to understand complex stock flow problems if the mode of presentation is adequate. System thinking ability is not firmly linked with a motivation to contribute to climate change mitigation. In a training study we show however that an increase of information about climate change can lead to a reduction of contributions

On the injectivity of the Kudla-Millson lift and surjectivity of the Borcherds lift

We consider the Kudla-Millson lift from elliptic modular forms of weight (p+q)/2 to closed q-forms on locally symmetric spaces corresponding to the orthogonal group O(p,q). We study the L²-norm of the lift following the Rallis inner product formula. We compute the contribution at the Archimedian place. For locally symmetric spaces associated to even unimodular lattices, we obtain an explicit formula for the L²-norm of the lift, which often implies that the lift is injective. For O(p,2) we discuss how such injectivity results imply the surjectivity of the Borcherds lift

Variational Calculation of the Effective Action

An indication of spontaneous symmetry breaking is found in the two-dimensional $\lambda\phi^4$ model, where attention is paid to the functional form of an effective action. An effective energy, which is an effective action for a static field, is obtained as a functional of the classical field from the ground state of the hamiltonian $H[J]$ interacting with a constant external field. The energy and wavefunction of the ground state are calculated in terms of DLCQ (Discretized Light-Cone Quantization) under antiperiodic boundary conditions. A field configuration that is physically meaningful is found as a solution of the quantum mechanical Euler-Lagrange equation in the $J\to 0$ limit. It is shown that there exists a nonzero field configuration in the broken phase of $Z_2$ symmetry because of a boundary effect.Comment: 26 pages, REVTeX, 7 postscript figures, typos corrected and two references adde