21,107 research outputs found
Robustness and Infrared Sensitivity of Various Observables in the Application of AdS/CFT to Heavy Ion Collisions
We investigate the robustness with respect to nonconformality of five
properties of strongly coupled plasmas that have been calculated in N=4
supersymmetric Yang-Mills (SYM) theory at nonzero temperature, motivated by the
goal of understanding phenomena in heavy ion collisions. (The properties are
the jet quenching parameter, the velocity dependence of screening, and the drag
and transverse and longitudinal momentum diffusion coefficients for a heavy
quark pulled through the plasma.) We use a toy model in which nonconformality
is introduced via a one-parameter deformation of the AdS black hole dual to the
hot N=4 SYM plasma. Upon introducing a degree of nonconformality comparable to
that seen in lattice calculations of QCD at temperatures a few times that of
the crossover to quark-gluon plasma, we find that the jet quenching parameter
is affected by the nonconformality by at most 30%, the screening length is
affected by at most 20%, but the drag and diffusion coefficients for a slowly
moving heavy quark can be modified by as much as 80%. However, four of the five
properties that we investigate become completely insensitive to the
nonconformality in the limit v -> 1. The exception is the jet quenching
parameter, which is "infrared sensitive" even at v=1, where it is defined. It
is the only high-velocity observable that we investigate which is sensitive to
properties of the medium at infrared energy scales proportional to T, namely
the scales where the quark-gluon plasma of QCD can be strongly coupled. The
other four quantities all probe only scales that are larger than T by a factor
that diverges as v -> 1, namely scales where the N=4 SYM plasma can be strongly
coupled but the quark-gluon plasma of QCD is not.Comment: Minor revisions, including expansion of Footnote 4. Version to appear
in JHEP. 36 pages, 5 figure
IMP-1 inhibits renal cell carcinoma 786-O cell growth by targeting EphrinB2 signaling pathway
EphrinB2 plays a critical role in tumor growth. In this study, we studied the antitumor activity of imperatorin derivative IMP-1 in renal cell carcinoma (RCC) by regulating EphrinB2 pathway.. Results showed that IMP-1 inhibited the proliferation of 786-O cells in a dose- and time-dependent manner. More importantly, knockdown and transfection of EphrinB2 altered the inhibitory effect of IMP-1 on the activity of 786-O cells. IMP-1 arrested 786-O cell cycle at G0/G1 phase by decreasing the expression of cyclin D1 and cyclin E. Moreover, IMP-1 regulated Bcl-2 family proteins’ expression, thus inducing apoptosis of 786-O cells. IMP-1 down-regulated the expression of EphrinB2, Syntenin1 and PICK1. Then, IMP-1 decreased the phosphorylation of Erk1/2 and AKT. In all, IMP-1 could regulate the EphrinB2 pathway in order to inhibit 786-O cell growth by arresting the cell cycle at G0/G1 phase and inducing cell apoptosis. Thus, IMP-1 may present as a potential strategy for RCC treatment
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