324 research outputs found

    Data on the number and frequency of scientific literature citations for established medulloblastoma cell lines

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    This article collates information about the number of scientific articles mentioning each of the established medulloblastoma cell lines, derived through a systematic search of Web of Science, Scopus and Google Scholar in 2016. The data for each cell line have been presented as raw number of citations, percentage share of the total citations for each search engine and as an average percentage between the three search engines. In order to correct for the time since each cell line has been in use, the raw citation data have also been divided by the number of years since the derivation of each cell line. This is a supporting article for a review of in vitro models of medulloblastoma published in “in vitro models of medulloblastoma: choosing the right tool for the job” (D.P. Ivanov, D.A. Walker, B. Coyle, A.M. Grabowska, 2016) [1]

    A Twistor Formulation of the Non-Heterotic Superstring with Manifest Worldsheet Supersymmetry

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    We propose a new formulation of the D=3D=3 type II superstring which is manifestly invariant under both target-space N=2N=2 supersymmetry and worldsheet N=(1,1)N=(1,1) super reparametrizations. This gives rise to a set of twistor (commuting spinor) variables, which provide a solution to the two Virasoro constraints. The worldsheet supergravity fields are shown to play the r\^ole of auxiliary fields.Comment: 21p., LaTe

    A twistor-like D=10 superparticle action with manifest N=8 world-line supersymmetry

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    We propose a new formulation of the D=10D=10 Brink-Schwarz superparticle which is manifestly invariant under both the target-space super-Poincar\'e group and the world-line local N=8N=8 superconformal group. This twistor-like construction naturally involves the sphere S8S^8 as a coset space of the D=10D=10 Lorentz group. The action contains only a finite set of auxiliary fields, but they appear in unusual trilinear combinations. The origin of the on-shell D=10D=10 fermionic κ\kappa symmetry of the standard Brink-Schwarz formulation is explained. The coupling to a D=10D=10 super-Maxwell background requires a new mechanism, in which the electric charge appears only on shell as an integration constant.Comment: 22pages, standard LATEX fil

    On superembedding approach to type IIB 7-branes

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    In search for a dynamical description of Q7-branes, which were known as solutions of supergravity equations and then conjectured to be dynamical objects of type IIB string theory, we study the superembedding description of 7-branes in curved type IIB supergravity superspace. With quite minimal and natural assumptions we have found that there is no place for Q7-branes as dynamical branes in superembedding approach. Our study might give implications for the old-standing problem of the covariant and supersymmetric description of multiple Dp-brane systems.Comment: LaTeX, 40 pages, no figures. V2: 44 pages, misprints corrected, minor cosmetic changes, improvements and extensions of discussion, in particular in the parts devoted to derivation of D7-brane equations of motion (Sec. 3) and in Secs. 4.2; appendices E,F added, footnote on page 30 extended, conclusions remain the same. V3. More misprints correcte

    Bosonic representation of one-dimensional Heisenberg ferrimagnets

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    The energy structure and the thermodynamics of ferrimagnetic Heisenberg chains of alternating spins S and s are described in terms of the Schwinger bosons and modified spin waves. In the Schwinger representation, we average the local constraints on the bosons and diagonalize the Hamiltonian at the Hartree-Fock level. In the Holstein-Primakoff representation, we optimize the free energy in two different ways introducing an additional constraint on the staggered magnetization. A new modified spin-wave scheme, which employs a Lagrange multiplier keeping the native energy structure free from temperature and thus differs from the original Takahashi Scheme, is particularly stressed as an excellent language to interpret one-dimensional quantum ferrimagnetism. Other types of one-dimensional ferrimagnets and the antiferromagnetic limit S=s are also mentioned.Comment: to be published in Phys. Rev. B 69, No. 6, 0644XX (2004

    Exotic Meson Production in the f1(1285)πf_{1}(1285)\pi^{-} System observed in the Reaction πpηπ+ππp\pi^{-} p \to \eta\pi^{+}\pi^{-}\pi^{-} p at 18 GeV/c

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    This letter reports results from the partial wave analysis of the πππ+η\pi^{-}\pi^{-}\pi^{+}\eta final state in πp\pi^{-}p collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, JPC=1+J^{PC} = 1^{-+} in the decay channel f1(1285)πf_{1}(1285)\pi^{-}. The mass M=1709±24±41M = 1709 \pm 24 \pm 41 MeV/c^2 and width Γ=403±80±115\Gamma = 403 \pm 80 \pm 115 MeV/c^2 of the first state are consistent with the parameters of the previously observed π1(1600)\pi_{1}(1600). The second resonance with mass M=2001±30±92M = 2001 \pm 30 \pm 92 MeV/c^2 and width Γ=333±52±49\Gamma = 333 \pm 52 \pm 49 MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of π2(1900)\pi_{2}(1900) is confirmed with mass M=2003±88±148M = 2003 \pm 88 \pm 148 MeV/c^2 and width Γ=306±132±121\Gamma = 306 \pm 132 \pm 121 MeV/c^2 and a new state, a1(2096)a_{1}(2096), is observed with mass M=2096±17±121M = 2096 \pm 17 \pm 121 MeV/c^2 and width Γ=451±41±81\Gamma = 451 \pm 41 \pm 81 MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers

    Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System

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    The exclusive reaction πpηπ0n\pi^- p \to \eta \pi^0 n, ηπ+ππ0\eta \to \pi^+ \pi^- \pi^0 at 18 GeV/c/c has been studied with a partial wave analysis on a sample of 23~492 ηπ0n\eta \pi^0 n events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the P+P_+ wave, thus providing evidence for a neutral exotic meson with JPC=1+J^{PC} = 1^{-+}, a mass of 1257±20±251257 \pm 20 \pm 25 MeV/c2/c^2, and a width of 354±64±60354 \pm 64 \pm 60 MeV/c2/c^2. New interpretations of the meson exotics in neutral ηπ0\eta \pi^0 system observed in E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase variations. p4, rewording paragrath "The second method ..." . p4, at the bottom of paragrath "The third method ..." added consistent with the results of methods 1 and 2

    Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c

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    Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures and 1 tabl

    Observation of Pseudoscalar and Axial Vector Resonances in pi- p -> K+ K- pi0 n at 18 GeV

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    A new measurement of the reaction pi- p -> K+ K- pi0 n has been made at a beam energy of 18 GeV. A partial wave analysis of the K+ K- pi0 system shows evidence for three pseudoscalar resonances, eta(1295), eta(1416), and eta(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed masses, widths and decay properties are reported. No signal was observed for C(1480), an IG J{PC} = 1+ 1{--} state previously reported in phi pi0 decay.Comment: 7 pages, 6 figs, to be submitted to Phys. Let

    Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2

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    We present a precise measurement of the deuteron longitudinal spin asymmetry A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1 GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A_1^d and g_1^d are found to be consistent with zero in the whole range of x.Comment: 17 pages, 10 figure
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