12,242 research outputs found

    Neurofibromin knockdown in glioma cell lines is associated with changes in cytokine and chemokine secretion in vitro.

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    The neurofibromin-1 tumor suppressor gene (NF1) is altered in approximately 20% of sporadic glioblastoma (GBM) cases. NF1 deficient GBM frequently shows a mesenchymal gene expression signature, suggesting a relationship between NF1 status and the tumor microenvironment. To identify changes in the production of secreted cytokines/chemokines in NF1 deficient glioma, we applied cytokine arrays to conditioned media from a panel of three GBM cell lines after siRNA-mediated NF1 knockdown. We identified increased secretion of platelet-derived growth factor AA (PDGF-AA), chitinase-3-like protein 1 (CHI3L1), interleukin-8 (IL-8), and endoglin (ENG) in different subsets of these cell lines. Secretion was associated with induction of the corresponding messenger RNA, suggesting a mechanism involving transcriptional upregulation. By contrast, in non-transformed immortalized normal human astrocytes, PDGF-AA secretion was increased upon NF1 knockdown, while secreted CHI3L1, ENG, and IL-8 were reduced or unchanged. Analysis of The Cancer Genome Atlas confirmed a relationship between glioma NF1 status and ENG and CHI3L1 in tumor samples. Overall, this study identifies candidate changes in secreted proteins from NF1 deficient glioma cells that could influence the tumor microenvironment, and suggests a direct link between NF1 loss and increased tumor cell production of CHI3L1 and endoglin, two factors implicated in mesenchymal identity in glioblastoma

    Robustness of baryon-strangeness correlation and related ratios of susceptibilities

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    Using quenched lattice QCD simulations we investigate the continuum limit of baryon-strangeness correlation and other related conserved charge-flavour correlations for temperatures T_c<T\le2T_c. By working with lattices having large temporal extents (N_\tau=12, 10, 8, 4) we find that these quantities are almost independent of the lattice spacing, i.e, robust. We also find that these quantities have very mild dependence on the sea quark mass and acquire values which are very close to their respective ideal gas limits. Our results also confirm robustness of the Wroblewski parameter.Comment: Published versio

    Determination of Freeze-out Conditions from Lattice QCD Calculations

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    Freeze-out conditions in Heavy Ion Collisions are generally determined by comparing experimental results for ratios of particle yields with theoretical predictions based on applications of the Hadron Resonance Gas model. We discuss here how this model dependent determination of freeze-out parameters may eventually be replaced by theoretical predictions based on equilibrium QCD thermodynamics.Comment: presented at the International Conference "Critical Point and Onset of Deconfinement - CPOD 2011", Wuhan, November 7-11, 201

    High-temperature ferroelectric order and magnetic field-cooled effect driven magnetoelectric coupling in R2BaCuO5 (R= Er, Dy, Sm)

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    The high-temperature ferroelectric order and a remarkable magnetoelectric effect driven by the magnetic field cooling are reported in R2BaCuO5 (R = Er, Dy, Sm) series. The ferroelectric (FE) orders are observed at much higher temperatures than their magnetic orders for all three members. The value of FE Curie temperature (TFE) is considerably high as ~ 235 K with the polarization value (P) of ~ 1410 {\mu}C/m2 for a 4 kV/cm poling field in case of Er2BaCuO5, whereas the values of TFE and P are also promising as ~ 232 K and ~ 992 {\mu}C/m2 for Dy2BaCuO5, and ~ 184 K and ~ 980 {\mu}C/m2 for Sm2BaCuO5. The synchrotron diffraction studies of Dy2BaCuO5 confirm a structural transition at TFE to a polar Pna21 structure, which correlates the FE order. An unusual magnetoelectric coupling is observed below the R order for Er and Dy compounds and below the Cu order for Sm compound, when the pyroelectric current is recorded only with the magnetic field both in heating and cooling cycles i.e. typical magnetic field cooled effect. The magnetic field cooled effect driven emergence of polarization is ferroelectric in nature, as it reverses due to the opposite poling field. The unexplored R2BaCuO5 series attracts the community for large TFE, high P value, and strange magnetoelectric consequences.Comment: 9 figures and 2 supporting figure

    PNJL model with a Van der Monde term

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    We extend the Polyakov-Nambu-Jona-Lasinio (PNJL) model for two degenerate flavours by including the effect of the SU(3) measure with a Van der Monde (VdM) term. This ensures that the Polyakov loop always remains in the domain [0,1]. The pressure, energy density, specific heat, speed of sound and conformal measure show small or negligible effects from this term. However various quark number and isospin susceptibilities are all found to approach their respective ideal gas limits around 2 TcT_c. We compare our methods with other similar approaches in PNJL model and also present a quantitative comparison with Lattice QCD data.Comment: 12 pages, 8 eps figures; extended discussion and reference added; accepted in Phys. Rev.

    An empirical analysis of the performance of pension funds: evidence from UK

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    Purpose - This paper examines the investment performance of pension funds in the UK using three standard performance measurement models, the CAPM, Fama-French model and the Carhart model. Design/methodology/approach - We use the CAPS-Mellon survey data for the period 1990-2008 and employ the three standard performance measurement models, the CAPM, Fama-French model and the Carhart model in assessing the investment performance of the pension funds. Findings - We show that the abnormal returns of pension funds cannot be fully explained by size, book-to-market values, market returns, momentum and the term spread. We find larger abnormal returns in bond than in equity portfolios and that smaller funds outperform larger funds. The paper also shows that the addition of the momentum factor does not improve on the three factor Fama-French model. We find that pension funds exhibit superior performance relative to the linear factor models. Research limitations/implications - This study contributes to the extant literature on pension funds performance. Future research may also extend our work to incorporate economic, tax, political and legal differences across the countries on the performance of pension funds. Secondly, due to data constraints, this study excludes the default probability of corporate bonds as an additional variable in their tests on bond returns. Future work may add the default probability as an additional variable whilst examining bond returns Practical implications - The authors believe that the findings will be considerable food for thought for fund managers who are continuously attempt to explore opportunities to provide a higher return to investors. Originality/value - To our knowledge this is the first comprehensive study that investigates the performance of UK equity and bond pension funds relative to standard linear factor models such as the CAPM, Fama and French (1993), and Carhart (1997)

    Exact solutions for semirelativistic problems with non-local potentials

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    It is shown that exact solutions may be found for the energy eigenvalue problem generated by the class of semirelativistic Hamiltonians of the form H = sqrt{m^2+p^2} + hat{V}, where hat{V} is a non-local potential with a separable kernel of the form V(r,r') = - sum_{i=1}^n v_i f_i(r)g_i(r'). Explicit examples in one and three dimensions are discussed, including the Yamaguchi and Gauss potentials. The results are used to obtain lower bounds for the energy of the corresponding N-boson problem, with upper bounds provided by the use of a Gaussian trial function.Comment: 13 pages, 3 figure
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