The effective Friedmann equation describing the evolution of the brane Universe in the cosmology of the Randall-Sundrum model includes a dark (or mirage or Weyl) radiation term. The brane evolution can be interpreted as the motion of the brane in an AdS-Schwarzschild bulk geometry. The energy density of the dark radiation is proportional to the black hole mass. We generalize this result for an ...

In this work, we model a radiofrequency discharge of hydrogenated silicon nitride in a capacitive coupled plasma reactor using Maxwellian and non-Maxwellian electron energy distribution function. The purpose is to investigate whether there is a real advantage and a significant contribution using non-Maxwellian electron energy distribution function rather than Maxwellian one for determining the ...

In solids the phonon-assisted, nonradiative decay from high-energy electronic excited states to low-energy electronic excited states is picosecond fast. It was hoped that electron and hole relaxation could be slowed down in quantum dots, due to the unavailability of phonons energy matched to the large energy-level spacings ("phonon-bottleneck"). However, excited-state relaxation was observed to...

* Presented as Paper IEPC-01-84 at the 27 International Electric Propulsion Conference, Pasadena, CA, 15-19 October, 2001. † Copyright © 2001 by the Electric Rocket Propulsion Society. All rights reserved. A grid lifetime model is presented for the lifetime estimation of a 3-grid ion engine system. The failure mechanism considered in the model is electron backstreaming due to charge exchange io...

a simple, inexpensive and one-step synthesis route of ag-tio2 nanoparticles by arc discharge method isreported. the resulting nanoparticles were characterized using x-ray diffraction and scanning electronmicroscopy. x-ray diffraction patterns demonstrate dominance of rutile to anatase phase in tio2 andformation of silver metal on tio2 after arc discharge process. scanning electron microscopy im...

This article has studied the effect of ratio of stiffness and thickness between piezoelectric actuators and host plat has been explored on optimal pattern for placement of piezoelectric work pieces around a hole in thin isotropic plate under static loading to reduce stress concentration. The piezoelectric actuators reduce directly or indirectly the stress concentration by applying positive and ...

Gradient flow in a potential energy (or Euclidean action) landscape provides a natural set of paths connecting different saddle points. We apply this method to General Relativity, where gradient flow is Ricci flow, and focus on the example of 4-dimensional Euclidean gravity with boundary S1 × S2, representing the canonical ensemble for gravity in a box. At high temperature the action has three ...

We discuss the status of the black hole entropy formula SBH = AH/4G in low energy effective field theory. The low energy expansion of the black hole entropy is studied in a non-equilibrium situation: the semiclassical decay of hot flat space by black hole nucleation. In this context the entropy can be defined as an enhancement factor in the semiclassical decay rate, which is dominated by a spha...

Measurements are presented of ion energy distributions produced within a prototype NSTAR discharge chamber as a function of its operational parameters. The goal of this effort is to document the ion energy distribution characteristics and determine features that could cause rapid sputter erosion of discharge chamber components. Ion energy distributions were measured with a Comstock model AC-901...