Description of inclusive meson spectra in e+e- annihilation reactions by a quark cascade model

We present a model to describe inclusive meson production in e+e- reactions based on a quark cascade approach whose formulation is put in terms of diffusion equations for three quark flavors (u, d, s). These equations are solved by using a formalism previously developed for the problem of the electromagnetic cascade generated in the atmosphere by cosmicray interactions. The obtained solutions are given in terms of a combination of power-law functions whose profiles are adequate to describe the characteristics observed in the inclusive spectrum of mesons.

Quantification of the bond-angle dispersion by Raman spectroscopy and the strain energy of amorphous silicon

A thorough critical analysis of the theoretical relationships between the bond-angle dispersion in a-Si, Δθ, and the width of the transverse optical Raman peak, Γ, is presented. It is shown that the discrepancies between them are drastically reduced when unified definitions for Δθ and Γ are used. This reduced dispersion in the predicted values of Δθ together with the broad agreement with the scarce direct determinations of Δθ is then used to analyze the strain energy in partially relaxed pure a-Si. It is concluded that defect annihilation does not contribute appreciably to the reduction of the a-Si energy during structural relaxation. In contrast, it can account for half of the crystallization energy, which can be as low as 7 kJ/mol in defect-free a-Si

I. Baryon-antibaryon phase transition at high temperature. II. Inclusive virtual photon-hadron reactions in the parton model

Part I

Present experimental data on nucleon-antinucleon scattering allow a study of the possibility of a phase transition in a nucleon-antinucleon gas at high temperature. Estimates can be made of the general behavior of the elastic phase shifts without resorting to theoretical derivation. A phase transition which separates nucleons from antinucleons is found at about 280 MeV in the approximation of the second virial coefficient to the free energy of the gas.

Part II

The parton model is used to derive scaling laws for the hadrons observed in deep inelastic electron-nucleon scattering which lie in the fragmentation region of the virtual photon. Scaling relations are obtained in the Bjorken and Regge regions. It is proposed that the distribution functions become independent of both q² and ν where the Bjorken and Regge regions overlap. The quark density functions are discussed in the limit x→1 for the nucleon octet and the pseudoscalar mesons. Under certain plausible assumptions it is found that only one or two quarks of the six types of quarks and antiquarks have an appreciable density function in the limit x→1. This has implications for the quark fragmentation functions near the large momentum boundary of their fragmentation region. These results are used to propose a method of measuring the proton and neutron quark density functions for all x by making measurements on inclusively produced hadrons in electroproduction only. Implications are also discussed for the hadrons produced in electron-positron annihilation.

Annihilation electrogenerated chemiluminescence of mixed metal chelates in solution : Modulating emission colour by manipulating the energetics

We demonstrate the mixed annihilation electrogenerated chemiluminescence of tris(2,2′-bipyridine)ruthenium(ii) with various cyclometalated iridium(iii) chelates. Compared to mixed ECL systems comprising organic luminophores, the absence of T-route pathways enables effective predictions of the observed ECL based on simple estimations of the exergonicity of the reactions leading to excited state production. Moreover, the multiple, closely spaced reductions and oxidations of the metal chelates provide the ability to finely tune the energetics and therefore the observed emission colour. Distinct emissions from multiple luminophores in the same solution are observed in numerous systems. The relative intensity of these emissions and the overall emission colour are dependent on the particular oxidized and reduced species selected by the applied electrochemical potentials. Finally, these studies offer insights into the importance of electronic factors in the question of whether the reduced or oxidized partner becomes excited in annihilation ECL. This journal is

Evidence of the participation of electronic excited states in the mechanism of positronium formation in substitutional Tb1-xEux(dpm)(3) solid solutions studied by optical and positron annihilation spectroscopies

Positronium formation in the bimary molecular solid solutions Tb1-xEux (dpm)(3) (dpm = dipivaloylmethanate) has been investigated. A strong linear correlation between the D-5(4) Tb(III) energy level excited state lifetime and the positronium formation probability has been observed. This correlation indicates that the ligand-to-metal charge transfer LMCT states act in both luminescence quenching and positronium formation inhibition, as previously proposed. A kinetic mechanism is proposed to explain this correlation and shows that excited electronic states have a very important role in the positronium formation mechanism.

Condensed phase combustion travelling waves with sequential exothermic or endothermic reactions

The one-dimensional propagation of a combustion wave through a premixed solid fuel for two-stage kinetics is studied. We re-examine the analysis of a single reaction travelling-wave and extend it to the case of two-stage reactions. We derive an expression for the travelling wave speed in the limit of large activation energy for both reactions. The analysis shows that when both reactions are exothermic, the wave structure is similar to the single reaction case. However, when the second reaction is endothermic, the wave structure can be significantly different from single reaction case. In particular, as might be expected, a travelling wave does not necessarily exist in this case. We establish conditions in the limiting large activation energy limit for the non-existence, and for monotonicity of the temperature profile in the travelling wave.

Towards a cognitive-behavioural intervention for adult grief reactions

Published accounts of behavioural interventions for grief have relied on exposure and habituation to grief cues as the primary strategy. Such an approach is excessively narrow, since it does not adequately confront the challenges that are posed by a bereavement. Many people cope with a bereavement by themselves, and for those, intervention may well be counterproductive. A cognitive-behavioural intervention, following models for depression/anxiety, can assist vulnerable individuals obtain a more rapid or complete adjustment. The proposed approach differs from dynamic treatments by placing less emphasis on defensive behavior, insight, and interpretation and more emphasis on training of coping skills.

The psychological management of adult grief reactions

Despite the severe challenges which are posed by the loss of a close friend or relative, bereavement has a relatively benign outcome in most cases. While the majority of patients cope with bereavement, a significant minority develop problems. A behavioural approach may help the bereaved avoid adverse grief reactions.

Australian student reactions to U.S. tourism advertising : a test of advertising as public diplomacy

A study among Australian college students gauged their reactions to a television commercial produced for the U.S. Commerce Department to bolster sagging tourism numbers among international visitors. In addition to using traditional measures applied to tourism advertisements, the student also concluded items to measure attitudes toward the U.S. government and its people Pre- and post-viewing results indicated that while the Hollywood-movie-themed commercial was not well received by the Australian students as a tourism message, it did result in more favorable attitudes toward the U.S. government, though not the U.S. people. The findings lend partial support for the potential of tourism advertising efforts to exert a "bleed-over effect" in terms of their contributions to overall attitudes toward a country, regardless of whether viewers plan to visit the country whose travel advertisements they see.

Australian student reactions to US tourism advertising : a test of advertising as public diplomacy

A study among Australian college students gauged their reactions to a television commercial produced for the US Commerce Department to bolster sagging tourism numbers among international visitors. In additional to using traditional measures applied to tourism advertisements, the study also included items to measure attitudes toward the US government and its people. Pre- and post-viewing results indicated that although the Hollywood-movie-themes commercial was not well received by the Australian students as a tourism message, it did result in more favourable attitudes toward the US government, although not the US people. The findings lend partial support for the potential of tourism advertising efforts to exert a 'bleed-over effect' in terms of their contribution to overall attitudes toward a country, regardless of whether viewers plan to visit the country whose travel advertisements of which they see.

Interventions for preventing and managing radiation-induced skin reactions in cancer patients (Protocol)

To assess the effects of any interventions which aim to prevent or manage radiation-induced skin reactions in people with cancer.

Highly efficient, stoichiometric radical exchange reactions using isoindoline profluorescent nitroxides

Exchange reactions between the isoindoline profluorescent nitroxide 1,1,3,3-tetramethyldibenzo[e,g]isoindolin-2-yloxyl (TMDBIO) and a TEMPO capped polystyrene were carried out. High conversions to the desired products were achieved using only stoichiometric ratios of nitroxide relative to polymer. The scope of this study was expanded by exploiting a di-nitroxide 9,10-bis(5-[1,1,3,3-tetramethylisoindolin-2-yloxy])anthracene (BTMIOA) as a connector between two polymer chains forming PS–nitroxide–PS systems.