756 research outputs found

    Dynamics of Anti-Proton -- Protons and Anti-Proton -- Nucleus Reactions

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    A short review of simulation results of anti-proton-proton and anti-proton-nucleus interactions within the framework of Geant4 FTF (Fritiof) model is presented. The model uses the main assumptions of the Quark-Gluon-String Model or Dual Parton Model. The model assumes production and fragmentation of quark-anti-quark and diquark-anti-diquark strings in the mentioned interactions. Key ingredients of the model are cross sections of string creation processes and an usage of the LUND string fragmentation algorithm. They allow one to satisfactory describe a large set of experimental data, especially, a strange particle production, Lambda hyperons and K mesons.Comment: 7 pages, 8 figure

    Simulation of neutron production in hadron-nucleus and nucleus-nucleus interactions in Geant4

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    Studying experimental data obtained at ITEP [1] on neutron production in interactions of protons with various nuclei in the energy range from 747 MeV up to 8.1 GeV, we have found that slow neutron spectra have scaling and asymptotic properties [2]. The spectra weakly depend on the collision energy at momenta of projectile protons larger than 5 - 6 GeV/c. These properties are taken into account in the Geant4 Fritiof (FTF) model. The improved FTF model describes as well as the Geant4 Bertini model the experimental data on neutron production by 1.2 GeV and 1.6 GeV protons on targets (Fe, Pb) [3] and by 3.0 GeV protons on various targets (Al, Fe, Pb) [4]. For neutron production in antiproton-nucleus interactions, it was demonstrated that the FTF results are in a satisfactory agreement with experimental data of the LEAR collaboration [5]. The FTF model gives promising results for neutron production in nucleus - nucleus interactions at projectile energy 1 - 2 GeV per nucleon [6]. The observed properties allow one to predict neutron yields in the nucleus-nucleus interactions at high and very high energies. Predictions for the NICA/MPD experiment at JINR are presented.Comment: 6 pages, 5 figures. Contribution to Proceedings of Baldin ISHEPP XXI

    Production of strange particles in hadronic interactions

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    The NA61/SHINE collaboration has recently published high precision data on production of π±\pi^\pm and K±K^\pm mesons, protons, antiprotons and Λ\Lambda hyperons in pp{\rm pp} interactions at 20, 31, 40, 80 and 158 GeV/c, and in pC{\rm pC} interactions at 31 GeV/c. The collaboration also presented experimental data on production of particles - π±\pi^\pm, K±K^\pm, p±p^\pm, ρ0\rho^0, ω\omega and K0K^{*0} in πC\pi^-{\rm C} collisions at 158 and 350 GeV/c. The collaboration has compared these data with various Monte Carlo model calculations: UrQMD, EPOS, GiBUU, and others. All of the models have various problems. The latest version of the FTF (Fritiof) model of Geant4 solves most of these problems. In the FTF model, we have improved the fragmentation of quark-gluon strings with small masses and introduced dependencies of probabilities of strange mesons and baryon-antibaryon pair's creation on string masses. Due to these changes, we describe the data of the NA61/SHINE collaboration on particle production in pp,pC{\rm pp, pC}, and πC\pi^-{\rm C} interactions. The improved Geant4 FTF model also well reproduces experimental data on inclusive cross sections of Λ,Λˉ\Lambda, \bar{\Lambda} and K0K^{0} production in antiproton-proton interactions at various energies. The modified FTF model allows one to simulate realistic processes with two particle productions - pˉpΛΛˉ\bar{p}p \rightarrow \Lambda \bar{\Lambda}, pˉpK+K\bar{p}p \rightarrow K^{+} K^{-}, pˉpΛΣˉ\bar{p}p \rightarrow \Lambda \bar{\Sigma}, and pˉpΣΣˉ\bar{p}p \rightarrow\Sigma \bar{\Sigma}, which will be studied in the future by the PANDA experiment at FAIR (GSI, Germany).Comment: 10 pages, 8 figures, IWNT-37, Rila, 2018, Bulgari

    A new development cycle of the Statistical Toolkit

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    The Statistical Toolkit is an open source system specialized in the statistical comparison of distributions. It addresses requirements common to different experimental domains, such as simulation validation (e.g. comparison of experimental and simulated distributions), regression testing in the course of the software development process, and detector performance monitoring. Various sets of statistical tests have been added to the existing collection to deal with the one sample problem (i.e. the comparison of a data distribution to a function, including tests for normality, categorical analysis and the estimate of randomness). Improved algorithms and software design contribute to the robustness of the results. A simple user layer dealing with primitive data types facilitates the use of the toolkit both in standalone analyses and in large scale experiments.Comment: To be published in the Proc. of CHEP (Computing in High Energy Physics) 201

    Geant4 FTF model description of the latest data by the NA61/SHINE collaboration on 40Ar+45Sc{\rm ^{40}Ar+{}^{45}Sc} interactions

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    It is shown that the Geant4 FTF model, which does not include the simulation of the hard parton-parton scattering and the formation of the quark-gluon plasma (QGP), describes well the NA61/SHINE data on π\pi^- meson distributions for the interactions at sNN=\sqrt{s_{NN}}= 5.2, 6.1, 7.6 and 8.8 GeV. At higher energies, sNN=\sqrt{s_{NN}}= 11.9 and 16.8 GeV, the model underestimates the data. This is considered as an indication of the formation of QGP at higher energies in central collisions of light and intermediate nuclei than in collisions of heavy nuclei (sNN6\sqrt{s_{NN}}\sim 6 GeV).Comment: 5 pages, 2 figure

    Herwig++ 2.0 Release Note

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    A new release of the Monte Carlo program Herwig++ (version 2.0) is now available. This is the first version of the program which can be used for hadron-hadron physics and includes the full simulation of both initial- and final-state QCD radiation.Comment: Source code and additional information available at http://hepforge.cedar.ac.uk/herwig

    Herwig++1.0: an event generator for e(+)e(-) annihilation

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    Results from the new Monte Carlo event generator Herwig++ are presented. This first version simulates Hadron Emission Reactions With Interfering Gluons in electron-positron annihilation. The parton shower evolution is carried out using new evolution variables suited to describing radiation from heavy quarks as well as light partons. The partonic final state is fragmented into hadrons by means of an improved cluster hadronization model. The results are compared with a wide variety of data from LEP and SLC

    Medicare for all

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    OBJECTIVES: Interferon (IFN) alpha is a key immunoregulatory cytokine secreted by activated plasmacytoid dendritic cells (PDC) that constitute less than 1% of leucocytes. IFNalpha plays an important role in the pathogenesis of systemic lupus erythematosus (SLE). Nevertheless, the natural IFNalpha inducers in SLE as well as the different IFNalpha secreting cell types are only partially characterised. METHODS: Chromatin was purified from calf thymus. Human peripheral blood mononuclear cells (PBMC), neutrophils and mouse bone marrow neutrophils were purified and cultured with different stimuli. IFNalpha production was estimated by flow cytometry, ELISA and a bioassay, and gene expression by quantitative real time PCR. Neutrophil activation and NETosis were analysed by flow cytometry, ELISA and confocal microscopy. RESULTS: Neutrophils produced a bioactive IFNalpha on stimulation with purified chromatin. IFNalpha secretion was observed with steady state neutrophils purified from 56 independent healthy individuals and autoimmune patients in response to free chromatin and not chromatin containing immune complexes. Chromatin induced IFNalpha secretion occurred independently of Toll-like receptor 9 (TLR9). Neutrophil priming by granulocyte-colony stimulating factor, granulocyte macrophage-colony stimulating factor or IFNalpha was not necessary but PBMC sustained IFNalpha secretion by neutrophils. PDC were 27 times more efficient than neutrophils but blood neutrophils were 100 times more frequent than PDC. Finally, neutrophil activation by chromatin was associated with NETosis and DNA sensor upregulation. CONCLUSIONS: Neutrophils have the capability of producing IFNalpha on selective triggering, and we identified a natural lupus stimulus involved, unveiling a new mechanism involved in SLE. Neutrophils represent another important source of IFNalpha and important targets for future therapies aimed at influencing IFNalpha levels

    Molecular Phylogentic Analysis of Marine Polychaeta and Crassostrea rivularis

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    底栖生物在海洋生态系统中起着极其重要的作用,部分底栖生物也是重要的海洋经济物种。同时因为海洋底栖动物活动性小、地区性强,可以较好地反映水质和地质的污染状况,在海洋污染生物学指标中具有特别重要的意义。因此对底栖生物进行正确的分类和系统发育学研究是十分必要的。过去对底栖生物的分类主要根据形态来划分,但是随着科学的发展传统形态学越来越遇到一些难以克服的障碍,如趋同进化的问题。另外用形态特征定义一个分类阶元,就必须对标本的完整性、性别、生长阶段有严格的要求,因此对于一些特殊条件下取得的很难保持完整的形态的标本来说,进行形态学的鉴定尤其困难。现代分子生物学的发展。使我们可以利用核酸、蛋白质等生物大分子的...Marine benthos play a very important role in the ecology of marine environment. Lots of the animals are also important economic marine species. Meanwhile, because they are characterized as narrow active and special territory distribution, they can be used to indicate the quality of water and the polluted condition of sediments, which is an important part of the biologic indication of marine pollut...学位:理学硕士院系专业:生命科学学院生物学系_生物化学与分子生物学学号:20012605

    CAP defines a second signalling pathway required for insulin-stimulated glucose transport

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    Insulin stimulates the transport of glucose into fat and muscle cells. Although the precise molecular mechanisms involved in this process remain uncertain, insulin initiates its actions by binding to its tyrosine kinase receptor, leading to the phosphorylation of intracellular substrates. One such substrate is the Cbl protooncogene product(1). Cbl is recruited to the insulin receptor by interaction with the adapter protein CAP, through one of three adjacent SH3 domains in the carboxy terminus of CAP(2). Upon phosphorylation of Cbl, the CAP-Cbl complex dissociates from the insulin receptor and moves to a caveolin-enriched, triton-insoluble membrane fraction(3). Here, to identify a molecular mechanism underlying this subcellular redistribution, we screened a yeast two-hybrid library using the amino-terminal region of CAP and identified the caveolar protein flotillin. Flotillin forms a ternary complex with CAP and Cbl, directing the localization of the CAP-Cbl complex to a lipid raft subdomain of the plasma membrane. Expression of the N-terminal domain of CAP in 3T3-L1 adipocytes blocks the stimulation of glucose transport by insulin, without affecting signalling events that depend on phosphatidylinositol-3-OH kinase. Thus, localization of the Cbl-CAP complex to lipid rafts generates a pathway that is crucial in the regulation of glucose uptake.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62940/1/407202a0.pd
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