A statistical method to estimate low-energy hadronic cross sections

In this article we propose a model based on the Statistical Bootstrap approach to estimate the cross sections of different hadronic reactions up to a few GeV in c.m.s energy. The method is based on the idea, when two particles collide a so called fireball is formed, which after a short time period decays statistically into a specific final state. To calculate the probabilities we use a phase space description extended with quark combinatorial factors and the possibility of more than one fireball formation. In a few simple cases the probability of a specific final state can be calculated analytically, where we show that the model is able to reproduce the ratios of the considered cross sections. We also show that the model is able to describe proton\,-\,antiproton annihilation at rest. In the latter case we used a numerical method to calculate the more complicated final state probabilities. Additionally, we examined the formation of strange and charmed mesons as well, where we used existing data to fit the relevant model parameters.Comment: 12 pages, 12 figures, submitted to EPJ

Evolutionary dynamics of protein domain architecture in plants

<p>Abstract</p> <p>Background</p> <p>Protein domains are the structural, functional and evolutionary units of the protein. Protein domain architectures are the linear arrangements of domain(s) in individual proteins. Although the evolutionary history of protein domain architecture has been extensively studied in microorganisms, the evolutionary dynamics of domain architecture in the plant kingdom remains largely undefined. To address this question, we analyzed the lineage-based protein domain architecture content in 14 completed green plant genomes.</p> <p>Results</p> <p>Our analyses show that all 14 plant genomes maintain similar distributions of species-specific, single-domain, and multi-domain architectures. Approximately 65% of plant domain architectures are universally present in all plant lineages, while the remaining architectures are lineage-specific. Clear examples are seen of both the loss and gain of specific protein architectures in higher plants. There has been a dynamic, lineage-wise expansion of domain architectures during plant evolution. The data suggest that this expansion can be largely explained by changes in nuclear ploidy resulting from rounds of whole genome duplications. Indeed, there has been a decrease in the number of unique domain architectures when the genomes were normalized into a presumed ancestral genome that has not undergone whole genome duplications.</p> <p>Conclusions</p> <p>Our data show the conservation of universal domain architectures in all available plant genomes, indicating the presence of an evolutionarily conserved, core set of protein components. However, the occurrence of lineage-specific domain architectures indicates that domain architecture diversity has been maintained beyond these core components in plant genomes. Although several features of genome-wide domain architecture content are conserved in plants, the data clearly demonstrate lineage-wise, progressive changes and expansions of individual protein domain architectures, reinforcing the notion that plant genomes have undergone dynamic evolution.</p

Importance of Taking Into Account the Soil Stratification in Reproducing the Late-Time Features of Distant Fields Radiated by Lightning

In this paper, we present an analysis of the propagation effect along a lossy ground on the characteristics of lightning-generated electric fields, using simultaneous observations of lightning currents and radiated fields measured at nine different distances associated with rocket-triggered lightning. The triggered-lightning site is located inConghua (Guangdong,China). The electric field waveforms were measured using the sensors belonging to the Foshan three-dimensional lightning location system that are located at distances from the triggered-lightning site ranging from 69 to 126 km. The propagation path was over land and mainly over flat ground. The field sensors used had an overall bandwidth from 160 Hz to 1MHz. It is shown that even though the early response of the field can be reproduced reasonably well by adjusting the ground electrical conductivity, the subsidiary peaks, and the late-time response of the fields cannot be satisfactorily reproduced assuming a homogeneous ground model. However, a two-layer soil model allows obtaining very good agreement between computed and measured waveforms for all the considered distances and events. Compared to the homogeneous ground case, the computed early-, intermediate-, and late-time response follows to a much better extent the experimental waveforms. We also provide a discussion on the influence of the computational model and parameters on the simulated results

Ind. Eng. Chem. Res.

A short-range Sutherland potential is mapped with the two-Yukawa potential and incorporated into the first-order mean spherical approximation (FMSA) theory to deal with the short-range dispersion interactions of ion-ion, ion-solvent, and solvent-solvent. An equation of state (EOS) based on primitive MSA and FMSA is constructed to describe the single- and multiple-salt solutions. With the universal and transferable ionic parameters derived from mean ionic activity coefficients and solution densities of single-salt solutions for five cations (Li+, Na+, K+, Ca2+, Mg2+) and five anions (Cl-, Br-, I-, NO3-, SO42- ), the proposed EOS predicts the correct osmotic coefficients as well as water activities for 19 monovalent and bivalent two-salt solutions. Without any additional mixing parameter, the predicted osmotic coefficients for aqueous two-salt solutions are in good agreement with experimental data.A short-range Sutherland potential is mapped with the two-Yukawa potential and incorporated into the first-order mean spherical approximation (FMSA) theory to deal with the short-range dispersion interactions of ion-ion, ion-solvent, and solvent-solvent. An equation of state (EOS) based on primitive MSA and FMSA is constructed to describe the single- and multiple-salt solutions. With the universal and transferable ionic parameters derived from mean ionic activity coefficients and solution densities of single-salt solutions for five cations (Li+, Na+, K+, Ca2+, Mg2+) and five anions (Cl-, Br-, I-, NO3-, SO42- ), the proposed EOS predicts the correct osmotic coefficients as well as water activities for 19 monovalent and bivalent two-salt solutions. Without any additional mixing parameter, the predicted osmotic coefficients for aqueous two-salt solutions are in good agreement with experimental data