Relativistic quantum transport theory of hadronic matter: the coupled nucleon, delta and pion system

We derive the relativistic quantum transport equation for the pion distribution function based on an effective Lagrangian of the QHD-II model. The closed time-path Green's function technique, the semi-classical, quasi-particle and Born approximation are employed in the derivation. Both the mean field and collision term are derived from the same Lagrangian and presented analytically. The dynamical equation for the pions is consistent with that for the nucleons and deltas which we developed before. Thus, we obtain a relativistic transport model which describes the hadronic matter with $N$, $\Delta$ and $\pi$ degrees of freedom simultaneously. Within this approach, we investigate the medium effects on the pion dispersion relation as well as the pion absorption and pion production channels in cold nuclear matter. In contrast to the results of the non-relativistic model, the pion dispersion relation becomes harder at low momenta and softer at high momenta as compared to the free one, which is mainly caused by the relativistic kinetics. The theoretically predicted free $\pi N \to \Delta$ cross section is in agreement with the experimental data. Medium effects on the $\pi N \to \Delta$ cross section and momentum-dependent $\Delta$-decay width are shown to be substantial.Comment: 66 pages, Latex, 12 PostScript figures included; replaced by the revised version, to appear in Phys. Rev.

Relativistic transport theory of N, \Delta and N^{*}(1440) interacting through σ\sigma, ω\omega and π\pi mesons

A self-consistent relativistic integral-differential equation of the Boltzmann-Uehling-Uhlenbeck-type for the $N^{*}$(1440) resonance is developed based on an effective Lagrangian of baryons interacting through mesons. The closed time-path Green's function technique and semi-classical, quasi-particle and Born approximations are employed in the derivation. The non-equilibrium RBUU-type equation for the $N^{*}$(1440) is consistent with that of nucleon's and delta's which we derived before. Thus, we obtain a set of coupled equations for the $N$, $\Delta$ and $N^{*}$(1440) distribution functions. All the $N^{*}$(1440)-relevant in-medium two-body scattering cross sections within the $N$, $\Delta$ and $N^{*}$(1440) system are derived from the same effective Lagrangian in addition to the mean field and presented analytically, which can be directly used in the study of relativistic heavy-ion collisions. The theoretical prediction of the free $pp \to pp^{*}(1440)$ cross section is in good agreement with the experimental data. We calculate the in-medium $N + N \to N + N^{*}$, $N^{*} + N \to N + N$ and $N^{*} + N \to N^{*} + N$ cross sections in cold nuclear matter up to twice the nuclear matter density. The influence of different choices of the $N^{*}N^{*}$ coupling strengths, which can not be obtained through fitting certain experimental data, are discussed. The results show that the density dependence of predicted in-medium cross sections are sensitive to the $N^{*}N^{*}$ coupling strengths used. An evident density dependence will appear when a large scalar coupling strength of $g_{N^{*}N^{*}}^{\sigma}$ is assumed.Comment: 64 pages, Latex, 13 PostScript figures include

RA Differentiation Enhances Dopaminergic Features, Changes Redox Parameters, and Increases Dopamine Transporter Dependency in 6-Hydroxydopamine-Induced Neurotoxicity in SH-SY5Y Cells

Experimental investigations were performed to characterize the mechanical properties of bamboo fiber-polyester composites. The composite laminates were fabricated by infusing different forms of untreated bamboo fibers (randomly oriented, bamboo textiles and bamboo foam cores) with polyester resin. The results showed that the engineered bamboo fiber composites have strength and stiffness properties suitable for structural applications. Among the tested composites, the laminates with randomly oriented bamboo fibers exhibited the highest strength properties. Its strength in flexure, tension, compression, and shear are 58, 35, 48, and 32 MPa, respectively and its Modulus of Elasticity (MOE) is 3.2GPa. However, only the tensile strength and MOE showed better properties to that of neat polyester resin which are 15% and 4% higher, re-spectively possibly due to relatively poor load transfer between the fibers and the matrix. Importantly, the flexural strength of the bamboo fiber-polyester composites is 200% and 30% higher than the standard particleboard and medium density fiberboard, respectively used in the construction industry. It is expected that the results of this preliminary study will provide information to support the development and application of this new generation composites in housing and construction

Connecting question answering and conversational agents: Contextualizing German questions for interactive question answering systems

Waltinger U, Breuing A, Wachsmuth I. Connecting question answering and conversational agents: Contextualizing German questions for interactive question answering systems. KI - Künstliche Intelligenz. 2012;26(4):381-390.Research results in the field of Question Answering (QA) have shown that the classification of natural language questions significantly contributes to the accuracy of the generated answers. In this paper we present an approach which extends the prevalent question classification techniques by additionally considering further contextual information provided by the questions. Thereby we focus on improving the conversational abilities of existing interactive interfaces by enhancing their underlying QA systems in terms of response time and correctness. As a result, we are able to introduce a method based on a tripartite contextualization. First, we present a comprehensive question classification experiment based on machine learning using two different datasets and various feature sets for the German language. Second, we propose a method for detecting the focus chunk of a given question, that is, for identifying which part of the question is fundamentally relevant to the answer and which part refers to a specification of it. Third, we investigate how to identify and label the topic of a given question by means of a human-judgment experiment. We show that the resulting contextualization method contributes to an improvement of existing question answering systems and enhances their application within interactive scenarios