147 research outputs found
Municipal Solid Waste Flow Control in the Post-Carbone World
Garbage will always ultimately be the government\u27s problem. Evolving environmental standards and state and federal policies will continue to require reasoned responses from local governments and municipal solid waste flow control is a vital cog in many jurisdictions\u27 solid waste management solutions. Without flow control of some form, governments\u27 ability to plan and provide for the most environmentally sound and economically acceptable solutions will wane, leaving the public vulnerable to the vagaries of a private market that does not have a duty to protect the public health and safety. The Carbone decision has blunted one of the local governments chief weapons-legislative flow control-and it appears Congress will not supply an adequate answer for many solid waste systems. More than ever, alternatives to legislative flow control will be needed to enable municipalities to fulfill their solid waste duties, to comply with federal and state mandates, and to provide workable, environmentally-sound, long-term solid waste programs serving the interests of the public health and safety. Local governments must act soon by examining these options and deciding which will best serve the public
Analytical Galaxy Profiles for Photometric and Lensing Analysis
This article introduces a family of analytical functions of the form x^{\nu}
K_{\nu}(x), where K_{\nu} is the incomplete Bessel function of the third kind.
This family of functions can describe the density profile, projected and
integrated light profiles and the gravitational potentials of galaxies. For the
proper choice of parameters, these functions accurately approximate Sersic
functions over a range of indices and are good fits to galaxy light profiles.
With an additional parameter corresponding to a galaxy core radius, these
functions can fit galaxy like M87 over a factor of 100,000 in radius. Unlike
Sersic profiles, these functions have simple analytical 2-dimensional and
3-dimensional Fourier transforms, so they are easily convolved with spatially
varying point spread function and are well suited for photometric and lensing
analysis. We use these functions to estimate the effects of seeing on lensing
measurements and show that high S/N measurements, even when the PSF is larger
than the galaxy effective radius, should be able to recover accurate estimates
of lensing distortions by weighting light in the outer isophotes that are less
effected by seeing
Master-equation analysis of accelerating networks
In many real-world networks, the rates of node and link addition are time
dependent. This observation motivates the definition of accelerating networks.
There has been relatively little investigation of accelerating networks and
previous efforts at analyzing their degree distributions have employed
mean-field techniques. By contrast, we show that it is possible to apply a
master-equation approach to such network development. We provide full
time-dependent expressions for the evolution of the degree distributions for
the canonical situations of random and preferential attachment in networks
undergoing constant acceleration. These results are in excellent agreement with
results obtained from simulations. We note that a growing, non-equilibrium
network undergoing constant acceleration with random attachment is equivalent
to a classical random graph, bridging the gap between non-equilibrium and
classical equilibrium networks.Comment: 6 pages, 1 figure, 1 tabl
Effective Hamiltonian study of excitations in a boson- fermion mixture with attraction between components
An effective Hamiltonian for the Bose subsystem in the mixture of ultracold
atomic clouds of bosons and fermions with mutual attractive interaction is used
for investigating collective excitation spectrum. The ground state and mode
frequencies of the Rb and K mixture are analyzed quantitatively
at zero temperature. We find analytically solutions of the hydrodynamics
equations in the Thomas- Fermi approximation. We discuss the relation between
the onset of collapse and collective modes softening and the dependence of
collective oscillations on scattering length and number of boson atoms.Comment: 9 pages, 5 figure
Convergence Characteristics of the Cumulant Expansion for Fourier Path Integrals
The cumulant representation of the Fourier path integral method is examined
to determine the asymptotic convergence characteristics of the imaginary-time
density matrix with respect to the number of path variables included. It is
proved that when the cumulant expansion is truncated at order , the
asymptotic convergence rate of the density matrix behaves like .
The complex algebra associated with the proof is simplified by introducing a
diagrammatic representation of the contributing terms along with an associated
linked-cluster theorem. The cumulant terms at each order are expanded in a
series such that the the asymptotic convergence rate is maintained without the
need to calculate the full cumulant at order . Using this truncated
expansion of each cumulant at order , the numerical cost in developing
Fourier path integral expressions having convergence order is
shown to be approximately linear in the number of required potential energy
evaluations making the method promising for actual numerical implementation.Comment: 47 pages, 2 figures, submitted to PR
On the distribution of estimators of diffusion constants for Brownian motion
We discuss the distribution of various estimators for extracting the
diffusion constant of single Brownian trajectories obtained by fitting the
squared displacement of the trajectory. The analysis of the problem can be
framed in terms of quadratic functionals of Brownian motion that correspond to
the Euclidean path integral for simple Harmonic oscillators with time dependent
frequencies. Explicit analytical results are given for the distribution of the
diffusion constant estimator in a number of cases and our results are confirmed
by numerical simulations.Comment: 14 pages, 5 figure
Brane Localization and Stabilization via Regional Physics
Extra-dimensional scenarios have become widespread among particle and
gravitational theories of physics to address several outstanding problems,
including cosmic acceleration, the weak hierarchy problem, and the quantization
of gravity. In general, the topology and geometry of the full spacetime
manifold will be non-trivial, even if our ordinary dimensions have the topology
of their covering space. Most compact manifolds are inhomogeneous, even if they
admit a homogeneous geometry, and it will be physically relevant where in the
extra-dimensions one is located. In this letter, we explore the use of both
local and global effects in a braneworld scenario to naturally provide
position-dependent forces that determine and stabilize the location of a single
brane. For illustrative purposes, we consider the 2-dimensional hyperbolic horn
and the Euclidean cone as toy models of the extra-dimensional manifold, and add
a brane wrapped around one of the two spatial dimensions. We calculate the
total energy due to brane tension and bending (extrinsic curvature) as well as
that due to the Casimir energy of a bulk scalar satisfying a Dirchlet boundary
condition on the brane. From the competition of at least two of these effects
there can exist a stable minimum of the effective potential for the brane
location. However, on more generic spaces (on which more symmetries are broken)
any one of these effects may be sufficient to stabilize the brane. We discuss
this as an example of physics that is neither local nor global, but regional.Comment: 4 pages, 2 figures. PRL submitte
Cross-correlations of the Lyman-alpha forest with weak lensing convergence I: Analytical Estimates of S/N and Implications for Neutrino Mass and Dark Energy
We expect a detectable correlation between two seemingly unrelated
quantities: the four point function of the cosmic microwave background (CMB)
and the amplitude of flux decrements in quasar (QSO) spectra. The amplitude of
CMB convergence in a given direction measures the projected surface density of
matter. Measurements of QSO flux decrements trace the small-scale distribution
of gas along a given line-of-sight. While the cross-correlation between these
two measurements is small for a single line-of-sight, upcoming large surveys
should enable its detection. This paper presents analytical estimates for the
signal to noise (S/N) for measurements of the cross-correlation between the
flux decrement and the convergence and for measurements of the
cross-correlation between the variance in flux decrement and the convergence.
For the ongoing BOSS (SDSS III) and Planck surveys, we estimate an S/N of 30
and 9.6 for these two correlations. For the proposed BigBOSS and ACTPOL
surveys, we estimate an S/N of 130 and 50 respectively. Since the
cross-correlation between the variance in flux decrement and the convergence is
proportional to the fourth power of , the amplitude of these
cross-correlations can potentially be used to measure the amplitude of
at z~2 to 2.5% with BOSS and Planck and even better with future data
sets. These measurements have the potential to test alternative theories for
dark energy and to constrain the mass of the neutrino. The large potential
signal estimated in our analytical calculations motivate tests with non-linear
hydrodynamical simulations and analyses of upcoming data sets.Comment: 24 pages, 9 figure
Lattice Green's function approach to the solution of the spectrum of an array of quantum dots and its linear conductance
In this paper we derive general relations for the band-structure of an array
of quantum dots and compute its transport properties when connected to two
perfect leads. The exact lattice Green's functions for the perfect array and
with an attached adatom are derived. The expressions for the linear conductance
for the perfect array as well as for the array with a defect are presented. The
calculations are illustrated for a dot made of three atoms. The results derived
here are also the starting point to include the effect of electron-electron and
electron-phonon interactions on the transport properties of quantum dot arrays.
Different derivations of the exact lattice Green's functions are discussed
Spacetime Properties of ZZ D-Branes
We study the tachyon and the RR field sourced by the ZZ D-branes in
type 0 theories using three methods. We first use the mini-superspace
approximation of the closed string wave functions of the tachyon and the RR
scalar to probe these fields. These wave functions are then extended beyond the
mini-superspace approximation using mild assumptions which are motivated by the
properties of the corresponding wave functions in the mini-superspace limit.
These are then used to probe the tachyon and the RR field sourced. Finally we
study the space time fields sourced by the ZZ D-branes using the FZZT
brane as a probe. In all the three methods we find that the tension of the
ZZ brane is times the tension of the ZZ brane. The RR
charge of these branes is non-zero only for the case of both and odd,
in which case it is identical to the charge of the brane. As a
consistency check we also verify that the space time fields sourced by the
branes satisfy the corresponding equations of motion.Comment: 32 pages, 4 figures. Clarifications on the principal characterization
of ZZ branes added. Reference adde
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