16 research outputs found
Affine Extension of Galilean Conformal Algebra in 2+1 Dimensions
We show that a class of nonrelativistic algebras including non
centrally-extended Schrodinger algebra and Galilean Conformal Algebra (GCA) has
an affine extension in 2+1 hitherto unknown. This extension arises out of the
conformal symmetries of the two dimensional complex plain. We suggest that this
affine form may be the symmetry that explains the relaxation of some classical
phenomena towards their critical point. This affine algebra admits a central
extension and maybe realized in the bulk. The bulk realization suggests that
this algebra may be derived by looking at the asymptotic symmetry of an AdS
theory. This suggests that AdS/CFT duality may take on a special form in four
dimensions.Comment: 13 pages, no figures. Some references added, typos corrected, minor
changes in conten
CFT dual of the AdS Dirichlet problem: Fluid/Gravity on cut-off surfaces
We study the gravitational Dirichlet problem in AdS spacetimes with a view to
understanding the boundary CFT interpretation. We define the problem as bulk
Einstein's equations with Dirichlet boundary conditions on fixed timelike
cut-off hypersurface. Using the fluid/gravity correspondence, we argue that one
can determine non-linear solutions to this problem in the long wavelength
regime. On the boundary we find a conformal fluid with Dirichlet constitutive
relations, viz., the fluid propagates on a `dynamical' background metric which
depends on the local fluid velocities and temperature. This boundary fluid can
be re-expressed as an emergent hypersurface fluid which is non-conformal but
has the same value of the shear viscosity as the boundary fluid. The
hypersurface dynamics arises as a collective effect, wherein effects of the
background are transmuted into the fluid degrees of freedom. Furthermore, we
demonstrate that this collective fluid is forced to be non-relativistic below a
critical cut-off radius in AdS to avoid acausal sound propagation with respect
to the hypersurface metric. We further go on to show how one can use this
set-up to embed the recent constructions of flat spacetime duals to
non-relativistic fluid dynamics into the AdS/CFT correspondence, arguing that a
version of the membrane paradigm arises naturally when the boundary fluid lives
on a background Galilean manifold.Comment: 71 pages, 2 figures. v2: Errors in bulk metrics dual to
non-relativistic fluids (both on cut-off surface and on the boundary) have
been corrected. New appendix with general results added. Fixed typos. 82
pages, 2 figure
A workbench for multigrid methods
SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
On the treatment of singularities in the multigrid method
SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
High-Precision Luminosity Instrumentation for the CMS Experiment at the HL-LHC
The High Luminosity upgrade of the LHC (HL-LHC) is foreseen to increase the instantaneous luminosity by a factor of five over the present LHC nominal value. The resulting, unprecedented requirements for background monitoring and luminosity measurements create the need for new high-precision instrumentation at CMS, using radiation hard detector technologies. This contribution discusses the implications of using the Tracker Endcap Pixel Detector for online measurements of luminosity and beam-induced background. The suitability of the TEPX detectormfor these tasks is explored and implementations for separate triggering and readout systems are explained
IL-9 production of naive CD4+ T cells depends on IL-2, is synergistically enhanced by a combination of TGF-beta and IL-4, and is inhibited by IFN-gamma
Dense CD4+ T cells isolated from naive mice produce only trace amounts of IL-9 when stimulated by immobilized anti-CD3 in combination with anti-CD28 Abs. In this situation, IL-9 production is significantly stimulated by TGF-beta and further enhanced by the addition of IL-4, which, by itself, has only a minimal influence. IFN-gamma was found to inhibit the enhancing effect of IL-4. However, increasing amounts of IL-4 in the presence of a constant concentration of IFN-gamma could overcome the inhibitory activity of IFN-gamma. The application of CD4+ T cells isolated from IL-2 knockout mice unequivocally revealed that IL-2 is essential for the production of IL-9 by T cells. In addition, the use of T cells from IL-4 knockout mice elucidated that the basic (IL-2 + TGF-beta) mediated IL-9 production is independent of IL-4. Therefore, our results demonstrate that optimal IL-9 production of naive dense CD4+ T cells is positively regulated at different levels: 1) by IL-2, which is essential for IL-9 secretion; 2) followed by TGF-beta, which promotes a considerable increase in IL-9 production above the level induced by IL-2; and 3) finally, by IL-4, which requires the presence of IL-2 and TGF-beta to strongly enhance the production of IL-9. IFN-gamma inhibits the production of IL-9 mainly at the level of IL-4 by neutralizing the effect of this cytokine