12,378 research outputs found
Neurofibromin knockdown in glioma cell lines is associated with changes in cytokine and chemokine secretion in vitro.
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
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
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)
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
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 . 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
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
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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