Quark-gluon vertex with an off-shell O(a)-improved chiral fermion action

We perform a study the quark-gluon vertex function with a quenched Wilson gauge action and a variety of fermion actions. These include the domain wall fermion action (with exponentially accurate chiral symmetry) and the Wilson clover action both with the non-perturbatively improved clover coefficient as well as with a number of different values for this coefficient. We find that the domain wall vertex function behaves very well in the large momentum transfer region. The off-shell vertex function for the on-shell improved clover class of actions does not behave as well as the domain wall case and, surprisingly, shows only a weak dependence on the clover coefficient $c_{SW}$ for all components of its Dirac decomposition and across all momenta. Including off-shell improvement rotations for the clover fields can make this action yield results consistent with those from the domain wall approach, as well as helping to determine the off-shell improved coefficient $c_q^\prime$.Comment: 11 pages, 13 figures, REVTeX

Heavy metal bioaccumulation by the important food plant, olea europaea L., in an ancient metalliferous polluted area of Cyprus

Aspects of the bioaccumulation of heavy metals are reviewed and possible evidence of homeostasis is highlighted. Examination and analysis of olive (Olea europaea L.) trees growing in close proximity to a copper dominated spoil tip dating from at least 2000 years BP, on the island of Cyprus, revealed both bioaccumulation and partitioning of copper, lead and zinc in various parts of the tree. A factor to quantify the degree of accumulation is illustrated and a possible seed protective mechanism suggested

A collaborative approach to learning programming: a hybrid learning model

The use of cooperative working as a means of developing collaborative skills has been recognised as vital in programming education. This paper presents results obtained from preliminary work to investigate the effectiveness of Pair Programming as a collaborative learning strategy and also its value towards improving programming skills within the laboratory. The potential of Problem Based Learning as a means of further developing cooperative working skills along with problem solving skills is also examined and a hybrid model encompassing both strategies outlined

Complexity and the Characterisation of Learning

Complexity theory offers an alternative to the simple causality and reductive accounts of change which dominate contemporary policy and practice. It does so by recognising that the interplay of dynamic elements results in the emergence of patterns and meanings that cannot be predicted by considering those elements in isolation. This symposium will show how complexity contests what it means to educate, and how it is related to existing philosophical traditions. This is the third of four papers presented at the workshop. It uses insights from complexity theory, along with the work of Gilles Deleuze, to critique existing characterisations of learning

Assessment of the performance of alternative aviation fuel in a modern air-spray combustor (MAC)

Recent concerns over energy security and environmental considerations have highlighted the importance of finding alternative aviation fuels. It is expected that coal and biomass derived fuels will fulfil a substantial part of these energy requirements. However, because of the physical and chemical difference in the composition of these fuels, there are potential problems associated with the efficiency and the emissions of the combustion process. Over the past 25 years Computational Fluid Dynamics (CFD) has become increasingly popular with the gas turbine industry as a design tool for establishing and optimising key parameters of systems prior to starting expensive trials. In this paper the performance of a typical aviation fuel, kerosene, an alternative aviation fuel, biofuel and a blend have been examined using CFD modelling. A good knowledge of the kinetics of the reaction of bio aviation fuels at both high and low temperature is necessary to perform reliable simulations of ignition, combustion and emissions in aero-engine. A novel detailed reaction mechanism was used to represent aviation fuel oxidation mechanism. The fuel combustion is calculated using a 3D commercial solver using a mixture fraction/pdf approach. Firstly, the study demonstrates that CFD predictions compare favourably with experimental data obtained by QinetiQ for a Modern Airspray Combustor (MAC) when used with traditional jet fuel (kerosene). Furthermore, the 3D CFD model has been refined to use the laminar flamelet model (LFM) approach that incorporates recently developed chemical reaction mechanisms for the bio-aviation fuel. This has enabled predictions for the bio-aviation fuel to be made. The impact of using the blended fuel has been shown to be very similar in performance to that of the 100% kerosene, confirming that aircraft running on 20% blended fuel should have no significant reduction in performance. It was also found that for the given operating conditions there is a significant reduction in performance when 100% biofuel if used. Additionally, interesting predictions were obtained, related to NOx emissions for the blend and 100% biofuel

The cumulative effects of known susceptibility variants to predict primary biliary cirrhosis risk.

Multiple genetic variants influence the risk for development of primary biliary cirrhosis (PBC). To explore the cumulative effects of known susceptibility loci on risk, we utilized a weighted genetic risk score (wGRS) to evaluate whether genetic information can predict susceptibility. The wGRS was created using 26 known susceptibility loci and investigated in 1840 UK PBC and 5164 controls. Our data indicate that the wGRS was significantly different between PBC and controls (P=1.61E-142). Moreover, we assessed predictive performance of wGRS on disease status by calculating the area under the receiver operator characteristic curve. The area under curve for the purely genetic model was 0.72 and for gender plus genetic model was 0.82, with confidence limits substantially above random predictions. The risk of PBC using logistic regression was estimated after dividing individuals into quartiles. Individuals in the highest disclosed risk group demonstrated a substantially increased risk for PBC compared with the lowest risk group (odds ratio: 9.3, P=1.91E-084). Finally, we validated our findings in an analysis of an Italian PBC cohort. Our data suggested that the wGRS, utilizing genetic variants, was significantly associated with increased risk for PBC with consistent discriminant ability. Our study is a first step toward risk prediction for PBC

Canonical Demon Monte Carlo Renormalization Group

We describe a new method to compute renormalized coupling constants in a Monte Carlo renormalization group calculation. The method can be used for a general class of models, e.g., lattice spin or gauge models. The basic idea is to simulate a joint system of block spins and canonical demons. In contrast to the Microcanonical Renormalization Group invented by Creutz et al. our method does not suffer from systematical errors stemming from a simultaneous use of two different ensembles. We present numerical results for the $O(3)$ nonlinear $\sigma$-model.Comment: LaTeX file, 7 pages, preprints CERN TH.7330/94, MS-TPI-

Z(3) Flavor Symmetry and Possible Implications

We show in this paper that the Z(3) flavor symmetry, which can successfully produce the tri-bimaximal mixing and flavor pattern of neutrino sector, has a possible explanation in the framework of gauge symmetry by constructing a wavefunction of flavor state particles with the help of the Wilson loop. In this implementation of Z(3) flavor symmetry, we suggest that the flavor charge in weak interaction can be interpreted as a topological charge. Its possible implications and generalizations to the quark sector are also discussed.Comment: 9 pages, no figures, final version for Phys. Lett.