9,514 research outputs found
Externalities revisited: the use of an environmental equity account
This exploratory paper attempts to restart a debate about the incorporation of environmental
externalities into the cost structure of the organisation. A number approaches are considered;
regulation together with all that would follow such as audit and policing; pollution permits, which
probably can only be used with a sinking lid application; and other charging mechanisms such as
making the private sector pay for public sector capital funding. The fourth alternative, the use of an
environmental equity account, has not been widely considered in the literature.
The paper proposes the use of an environmental equity account (after Boone and Rubenstein,
1997) with the express intent of generating a charge for environmental impact based on the cost of
control. That is, the cost of implementing state of the art technology compared to that currently in
use within the organisation, is used as a balance which may be either paid as a capital sum or
carried as a balance sheet entry upon which dividend payments would have to be made. It is
envisaged that both capital sums and dividend payments would go to an agency responsible for
environmental remediation activity
Vector boson production in association with KK modes of the ADD model to NLO in QCD at LHC
Next-to-leading order QCD corrections to the associated production of vector
boson (Z/W) with the the Kaluza-Klein modes of the graviton in large extra
dimensional model at the LHC, are presented. We have obtained various kinematic
distributions using a Monte Carlo code which is based on the two cut off phase
space slicing method that handles soft and collinear singularities appearing at
NLO level. We estimate the impact of the QCD corrections on various observables
and find that they are significant. We also show the reduction in factorization
scale uncertainty when QCD corrections are included.Comment: 12 pages, 5 figure
X-ray Isophotes in a Rapidly Rotating Elliptical Galaxy: Evidence of Inflowing Gas
We describe two-dimensional gasdynamical computations of the X-ray emitting
gas in the rotating elliptical galaxy NGC 4649 that indicate an inflow of about
one solar mass per year at every radius. Such a large instantaneous inflow
cannot have persisted over a Hubble time. The central constant-entropy
temperature peak recently observed in the innermost 150 parsecs is explained by
compressive heating as gas flows toward the central massive black hole. Since
the cooling time of this gas is only a few million years, NGC 4649 provides the
most acutely concentrated known example of the cooling flow problem in which
the time-integrated apparent mass that has flowed into the galactic core
exceeds the total mass observed there. This paradox can be resolved by
intermittent outflows of energy or mass driven by accretion energy released
near the black hole. Inflowing gas is also required at intermediate kpc radii
to explain the ellipticity of X-ray isophotes due to spin-up by mass ejected by
stars that rotate with the galaxy and to explain local density and temperature
profiles. We provide evidence that many luminous elliptical galaxies undergo
similar inflow spin-up. A small turbulent viscosity is required in NGC 4649 to
avoid forming large X-ray luminous disks that are not observed, but the
turbulent pressure is small and does not interfere with mass determinations
that assume hydrostatic equilibrium.Comment: 21 pages, 9 figures, accepted for publication by Ap
Axion Production from Landau Quantization in the Strong Magnetic Field of Magnetars
We utilize an exact quantum calculation to explore axion emission from
electrons and protons in the presence of the strong magnetic field of
magnetars. The axion is emitted via transitions between the Landau levels
generated by the strong magnetic field. The luminosity of axions emitted by
protons is shown to be much larger than that of electrons and becomes stronger
with increasing matter density. Cooling by axion emission is shown to be much
larger than neutrino cooling by the Urca processes. Consequently, axion
emission in the crust may significantly contribute to the cooling of magnetars.
In the high-density core, however, it may cause heating of the magnetar.Comment: 14 pages, 3 figure
Hydrostatic Gas Constraints On Supermassive Black Hole Masses: Implications For Hydrostatic Equilibrium And Dynamical Modeling In A Sample Of Early-Type Galaxies
We present new mass measurements for the supermassive black holes (SMBHs) in the centers of three early-type galaxies. The gas pressure in the surrounding, hot interstellar medium (ISM) is measured through spatially resolved spectroscopy with the Chandra X-ray Observatory, allowing the SMBH mass (M(BH)) to be inferred directly under the hydrostatic approximation. This technique does not require calibration against other SMBH measurement methods and its accuracy depends only on the ISM being close to hydrostatic, which is supported by the smooth X-ray isophotes of the galaxies. Combined with results from our recent study of the elliptical galaxy NGC4649, this brings the number of galaxies with SMBHs measured in this way to four. Of these, three already have mass determinations from the kinematics of either the stars or a central gas disk, and hence join only a handful of galaxies with MBH measured by more than one technique. We find good agreement between the different methods, providing support for the assumptions implicit in both the hydrostatic and the dynamical models. The stellar mass-to-light ratios for each galaxy inferred by our technique are in agreement with the predictions of stellar population synthesis models assuming a Kroupa initial mass function (IMF). This concurrence implies that no more than similar to 10%-20% of the ISM pressure is nonthermal, unless there is a conspiracy between the shape of the IMF and nonthermal pressure. Finally, we compute Bondi accretion rates (M(bondi)), finding that the two galaxies with the highest M(bondi) exhibit little evidence of X-ray cavities, suggesting that the correlation with the active galactic nuclei jet power takes time to be established.NASA NAS5-26555, NNG04GE76G, G07-8083XAstronom
Fully quantum mechanical dynamic analysis of single-photon transport in a single-mode waveguide coupled to a traveling-wave resonator
We analyze the dynamics of single photon transport in a single-mode waveguide
coupled to a micro-optical resonator using a fully quantum mechanical model. We
examine the propagation of a single-photon Gaussian packet through the system
under various coupling conditions. We review the theory of single photon
transport phenomena as applied to the system and we develop a discussion on the
numerical technique we used to solve for dynamical behavior of the quantized
field. To demonstrate our method and to establish robust single photon results,
we study the process of adiabatically lowering or raising the energy of a
single photon trapped in an optical resonator under active tuning of the
resonator. We show that our fully quantum mechanical approach reproduces the
semi-classical result in the appropriate limit and that the adiabatic invariant
has the same form in each case. Finally, we explore the trapping of a single
photon in a system of dynamically tuned, coupled optical cavities.Comment: 24 pages, 10 figure
Generation of Curvature Perturbations with Extra Anisotropic Stress
We study the evolution of curvature perturbations and the cosmic microwave
background (CMB) power spectrum in the presence of an hypothesized extra
anisotropic stress which might arise, for example, from the dark radiation term
in brane-world cosmology. We evolve the scalar modes of such perturbations
before and after neutrino decoupling and analyze their effects on the CMB
spectrum. A novel result of this work is that the cancellation of the neutrino
and extra anisotropic stress could lead to a spectrum of residual curvature
perturbations which is similar to the observed CMB power spectrum. This implies
a possible additional consideration in the determination of cosmological
parameters from the CMB analysis.Comment: 13 pages, 2 figures; improved discussio
Revised Relativistic Hydrodynamical Model for Neutron-Star Binaries
We report on numerical results from a revised hydrodynamic simulation of
binary neutron-star orbits near merger. We find that the correction recently
identified by Flanagan significantly reduces but does not eliminate the
neutron-star compression effect. Although results of the revised simulations
show that the compression is reduced for a given total orbital angular
momentum, the inner most stable circular orbit moves to closer separation
distances. At these closer orbits significant compression and even collapse is
still possible prior to merger for a sufficiently soft EOS. The reduced
compression in the corrected simulation is consistent with other recent studies
of rigid irrotational binaries in quasiequilibrium in which the compression
effect is observed to be small. Another significant effect of this correction
is that the derived binary orbital frequencies are now in closer agreement with
post-Newtonian expectations.Comment: Submitted to Phys. Rev.
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