Anomalous f_1 exchange in vector meson photoproduction asymmetries

We perform an analysis of the elastic production of vector mesons with polarized photon beams at high energy in order to investigate the validity of a recently proposed dynamical mechanism based on the dominance of the f_1 trajectory at large momentum transfer. The density matrix characterizing the angular distributions of the vector meson decays is calculated within an exchange model which includes the Pomeron and the f_1. The asymmetries of these decays turn out to be very useful to disentangle the role of these exchanges since their effect depends crucially on their quantum numbers which are different. The observables analyzed are accessible with present experimental facilities.Comment: 10 pages, REVTeX, 4 figures, some figures are corrected, conclusions unchange

How strongly do word reading times and lexical decision times correlate? Combining data from eye movement corpora and megastudies

We assess the amount of shared variance between three measures of visual word recognition latencies: eye movement latencies, lexical decision times and naming times. After partialling out the effects of word frequency and word length, two well-documented predictors of word recognition latencies, we see that 7-44% of the variance is uniquely shared between lexical decision times and naming times, depending on the frequency range of the words used. A similar analysis of eye movement latencies shows that the percentage of variance they uniquely share either with lexical decision times or with naming times is much lower. It is 5 – 17% for gaze durations and lexical decision times in studies with target words presented in neutral sentences, but drops to .2% for corpus studies in which eye movements to all words are analysed. Correlations between gaze durations and naming latencies are lower still. These findings suggest that processing times in isolated word processing and continuous text reading are affected by specific task demands and presentation format, and that lexical decision times and naming times are not very informative in predicting eye movement latencies in text reading once the effect of word frequency and word length are taken into account. The difference between controlled experiments and natural reading suggests that reading strategies and stimulus materials may determine the degree to which the immediacy-of-processing assumption and the eye-mind assumption apply. Fixation times are more likely to exclusively reflect the lexical processing of the currently fixated word in controlled studies with unpredictable target words rather than in natural reading of sentences or texts

Dielectric and conductivity relaxation in mixtures of glycerol with LiCl

We report a thorough dielectric characterization of the alpha relaxation of glass forming glycerol with varying additions of LiCl. Nine salt concentrations from 0.1 - 20 mol% are investigated in a frequency range of 20 Hz - 3 GHz and analyzed in the dielectric loss and modulus representation. Information on the dc conductivity, the dielectric relaxation time (from the loss) and the conductivity relaxation time (from the modulus) is provided. Overall, with increasing ion concentration, a transition from reorientationally to translationally dominated behavior is observed and the translational ion dynamics and the dipolar reorientational dynamics become successively coupled. This gives rise to the prospect that by adding ions to dipolar glass formers, dielectric spectroscopy may directly couple to the translational degrees of freedom determining the glass transition, even in frequency regimes where usually strong decoupling is observed.Comment: 8 pages, 7 figure

Nucleonic resonance excitations with linearly polarized photon in γp→ωp\gamma p\to \omega p

In this work, an improved quark model approach to the $\omega$ meson photo-production with an effective Lagrangian is presented. The {\it t}-channel {\it natural}-parity exchange is taken into account through the Pomeron exchange, while the {\it unnatural}-parity exchange is described by the $\pi^0$ exchange. With a very limited number of parameters, the available experimental data in the low energy regime can be consistently accounted for. We find that the beam polarization observables show sensitivities to some {\it s}-channel individual resonances in the $SU(6)\otimes O(3)$ quark model symmetry limit. Especially, the two resonances $P_{13}(1720)$ and $F_{15}(1680)$, which belong to the representation $[{\bf 56, ^2 8}, 2, 2, J]$, have dominant contributions over other excited states. Concerning the essential motivation of searching for "missing resonances" in meson photo-production, this approach provides a feasible framework, on which systematic investigations can be done.Comment: 16 pages, Revtex, 9 eps figures, to appear in PR

Pomeron exchange and exclusive electroproduction of rho-mesons in QCD

A Pomeron-exchange model of exclusive electroproduction of $\rho$-mesons is examined using a dressed-quark propagator. It is shown that by representing the photon-$\rho$-meson-Pomeron coupling by a nonperturbative, confined-quark loop, one obtains predictions for $\rho$-meson electroproduction that are in good agreement with experiment.Comment: 10 pages, 4 figures, uses epsfig and elsart.sty. Minor revisions to match version publishe

An isotopic effect in phi photoproduction at a few GeV

A distinct isotopic effect in phi photoproduction at 2-5 GeV region is identified by examining the production amplitudes due to Pomeron-exchange and meson-exchange mechanisms. This effect is mainly caused by the pi-eta interference constrained by SU(3) symmetry and the isotopic structure of the gamma NN coupling in the direct phi-radiation amplitude. It can be tested experimentally by measuring differences in the polarization observables between the gamma-p and gamma-n reactions.Comment: 11 pages, 6 figure

Integrated computer-aided working-fluid design and thermoeconomic ORC system optimisation

The successful commercialisation of organic Rankine cycle (ORC) systems across a range of power outputs and heat-source temperatures demands step-changes in both improved thermodynamic performance and reduced investment costs. The former can be achieved through high-performance components and optimised system architectures operating with novel working-fluids, whilst the latter requires careful component-technology selection, economies of scale, learning curves and a proper selection of materials and cycle configurations. In this context, thermoeconomic optimisation of the whole power-system should be completed aimed at maximising profitability. This paper couples the computer-aided molecular design (CAMD) of the working-fluid with ORC thermodynamic models, including recuperated and other alternative (e.g., partial evaporation or trilateral) cycles, and a thermoeconomic system assessment. The developed CAMD-ORC framework integrates an advanced molecular-based group-contribution equation of state, SAFT-γ Mie, with a thermodynamic description of the system, and is capable of simultaneously optimising the working-fluid structure, and the thermodynamic system. The advantage of the proposed CAMD-ORC methodology is that it removes subjective and pre-emptive screening criteria that would otherwise exist in conventional working-fluid selection studies. The framework is used to optimise hydrocarbon working-fluids for three different heat sources (150, 250 and 350 °C, each with mcp = 4.2 kW/K). In each case, the optimal combination of working-fluid and ORC system architecture is identified, and system investment costs are evaluated through component sizing models. It is observed that optimal working fluids that minimise the specific investment cost (SIC) are not the same as those that maximise power output. For the three heat sources the optimal working-fluids that minimise the SIC are isobutane, 2-pentene and 2-heptene, with SICs of 4.03, 2.22 and 1.84 £/W respectively

Effect of fermionic components on trion-electron scattering

To test the validity of replacing a composite fermion by an elementary fermion, we here calculate the transition rate from a state made of one free electron and one trion to a similar electron-trion pair, through the time evolution of such a pair induced by Coulomb interaction between elementary fermions. To do it in a convenient way, we describe the trion as one electron interacting with one exciton, and we use the tools we have developed in the new composite-exciton many-body theory. The trion-electron scattering contains a direct channel in which ``in'' and ``out'' trions are made with the same fermions, and an exchange channel in which the ``in'' free electron becomes one of the ``out'' trion components. As expected, momenta are conserved in these two channels. The direct scattering is found to read as the bare Coulomb potential between elementary particles multiplied by a form factor which depends on the ``in'' and ``out'' trion relative motion indices $\eta$ and $\eta'$, this factor reducing to $\delta_{\eta\eta'}$ in the zero momentum transfer limit: In this direct channel, the trion at large distance reacts as an elementary particle, its composite nature showing up for large momentum transfer. On the contrary, the fact that the trion is not elementary does affect the exchange channel for all momentum transfers. We thus conclude that a 3-component fermion behaves as an elementary fermion for direct processes in the small momentum transfer limit only

The status of GEO 600

The GEO 600 laser interferometer with 600m armlength is part of a worldwide network of gravitational wave detectors. GEO 600 is unique in having advanced multiple pendulum suspensions with a monolithic last stage and in employing a signal recycled optical design. This paper describes the recent commissioning of the interferometer and its operation in signal recycled mode

Identification of salt tolerance QTL in a wheat RIL mapping population using destructive and non-destructive phenotyping

Published online 24 August 2020. Corrected by: Corrigendum to: Identification of salt tolerance QTL in a wheat RIL mapping population using destructive and non-destructive phenotyping. Muhammad A. Asif, et al. Functional Plant Biology 49(7) 672 - 672. In the Acknowledgements, the ARC Centre of Excellence funding number was incorrect. The correct funding number is: CE140100008.Bread wheat (Triticum aestivum L.) is one of the most important food crops, however it is only moderately tolerant to salinity stress. To improve wheat yield under saline conditions, breeding for improved salinity tolerance of wheat is needed. We have identified nine quantitative trail loci (QTL) for different salt tolerance sub-traits in a recombinant inbred line (RIL) population, derived from the bi-parental cross of Excalibur × Kukri. This population was screened for salinity tolerance subtraits using a combination of both destructive and non-destructive phenotyping. Genotyping by sequencing (GBS) was used to construct a high-density genetic linkage map, consisting of 3236 markers, and utilised for mapping QTL. Of the nine mapped QTL, six were detected under salt stress, including QTL for maintenance of shoot growth under salinity (QG(1-5).asl-5A, QG(1-5).asl-7B) sodium accumulation (QNa.asl-2A), chloride accumulation (QCl.asl-2A, QCl.asl-3A) and potassium:sodium ratio (QK:Na.asl-2DS2). Potential candidate genes within these QTL intervals were shortlisted using bioinformatics tools. These findings are expected to facilitate the breeding of new salt tolerant wheat cultivars.Muhammad A. Asif, Melissa Garcia, Joanne Tilbrook, Chris Brien, Kate Dowling, Bettina Berger, Rhiannon K. Schilling, Laura Short, Christine Trittermann, Matthew Gilliham, Delphine Fleury, Stuart J. Roy and Allison S. Pearso