4,894 research outputs found
Scalar field perturbations of the Schwarzschild black hole in the G\"{o}del Universe
We investigate the scalar field perturbations of the 4+1-dimensional
Schwarzschild black hole immersed in a G\"{o}del Universe, described by the
Gimon-Hashimoto solution.This may model the influence of the possible rotation
of the Universe upon the radiative processes near a black hole. In the regime
when the scale parameter of the G\"{o}del background is small, the
oscillation frequency is linearly decreasing with , while the damping time
is increasing. The quasinormal modes are damping, implying stability of the
Schwarzschild-G\"{o}del space-time against scalar field perturbations. The
approximate analytical formula for large multipole numbers is found.Comment: 13 pages, 4 figures, 1 table, misprints corrected, to be published in
Phys.Rev.
Screening in three-dimensional QED with arbitrary fermion mass
We compute the quark--antiquark potential in three dimensional massive
Quantum Electrodynamics for arbitrary fermion mass. The result indicates that
screening prevails for any quark masses, contrary to the classical
expectations, generalizing our previous result obtained for large masses. We
also test the validity of several approximation schemes using a detailed
numerical analysis. The classical result is still reproduced for small
separation of the quarks.Comment: latex, 10 pages, 4 figures (6 ps-files
NATURAL RESOURCES AND RURAL DEVELOPMENT
Community/Rural/Urban Development,
A role for Gle1, a regulator of DEAD-box RNA helicases, at centrosomes and basal bodies.
Control of organellar assembly and function is critical to eukaryotic homeostasis and survival. Gle1 is a highly conserved regulator of RNA-dependent DEAD-box ATPase proteins, with critical roles in both mRNA export and translation. In addition to its well-defined interaction with nuclear pore complexes, here we find that Gle1 is enriched at the centrosome and basal body. Gle1 assembles into the toroid-shaped pericentriolar material around the mother centriole. Reduced Gle1 levels are correlated with decreased pericentrin localization at the centrosome and microtubule organization defects. Of importance, these alterations in centrosome integrity do not result from loss of mRNA export. Examination of the Kupffer's vesicle in Gle1-depleted zebrafish revealed compromised ciliary beating and developmental defects. We propose that Gle1 assembly into the pericentriolar material positions the DEAD-box protein regulator to function in localized mRNA metabolism required for proper centrosome function
Integrable models: from dynamical solutions to string theory
We review the status of integrable models from the point of view of their
dynamics and integrability conditions. Some integrable models are discussed in
detail. We comment on the use it is made of them in string theory. We also
discuss the Bethe Ansatz solution of the SO(6) symmetric Hamiltonian with SO(6)
boundary.
This work is especially prepared for the seventieth anniversaries of
Andr\'{e} Swieca (in memoriam) and Roland K\"{o}berle.Comment: 24 pages, to appear in Brazilian Journal of Physic
Non-Abelian Gauged Chiral Boson with a Generalized Faddevian Regularization
We consider non-Abelian gauged version of chiral boson with a generalized
Faddeevian regularization. It is a second class constrained theory. We quantize
the theory and analyze the phase space. It is shown that in spite of the lack
of manifest Lorentz invariance in the action, it has a consistent and Poincare'
invariant phase space structure.Comment: 10 pages latex fil
Pressure-rise Characteristics for a Liquid Hydrogen Dewar for Homogeneous, Normal Gravity Quiescent, and Zero Gravity Tests
Pressure rise characteristics of liquid hydrogen dewar for homogeneous, normal-gravity quiescent, and zero-gravity test
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