134,187 research outputs found
Similarity parameters for radiative energy transfer in isothermal and non-isothermal gas mixtures
The similarity groups for multicomponent, reacting gas mixtures with radiative
energy transport are derived (Section I). The resulting relations are used to consider
the feasibility if scaling for flow processes with radiative energy transport under
highly simplified conditions (Sections 2 and 3). Next the scaling parameters are
derived for radiant energy emission from isobaric and isothermal gases for
arbitrary opacities and various spectral line and molecular band models (Section 4).
Scaling parameters for radiant energy emission from isobaric but non-isothermal
systems are discussed for arbitrary opacities and various spectral line and molecular
band models under the restrictions imposed on the allowed temperature profiles for
dispersion and Doppler lines by the Eddington-Barbier approximation (Section 5).
Finally, we consider the radiative scaling properties for representative
temperature profiles for both collision-broadened and Doppler-broadened line
profiles on the basis if exact numerical calculations that we have performed for a
rotational spectral line belonging to a molecular vibration-rotation band. (Section
6). It appears that simple scaling rules generally constitute a fair approximation
for dispersion lines in non-isothermal systems but that corresponding relations
apply to lines with Doppler contour only in the transparent gas regime
Concentrated Poverty: A Change in Course
Examines how the distribution of concentrated poverty in metropolitan areas has shifted in the past two decades, using data from the Neighborhood Change Database
Have MTO Families Lost Access to Opportunity Neighborhoods Over Time?
Reviews research on families who moved to lower-poverty areas through the Moving to Opportunity program, using new data and broader indicators to assess whether their subsequent moves were also to better neighborhoods from which the families benefited
Improving estimates of the number of fake leptons and other mis-reconstructed objects in hadron collider events: BoB's your UNCLE. (Previously "The Matrix Method Reloaded")
We consider current and alternative approaches to setting limits on new
physics signals having backgrounds from misidentified objects; for example jets
misidentified as leptons, b-jets or photons. Many ATLAS and CMS analyses have
used a heuristic matrix method for estimating the background contribution from
such sources. We demonstrate that the matrix method suffers from statistical
shortcomings that can adversely affect its ability to set robust limits. A
rigorous alternative method is discussed, and is seen to produce fake rate
estimates and limits with better qualities, but is found to be too costly to
use. Having investigated the nature of the approximations used to derive the
matrix method, we propose a third strategy that is seen to marry the speed of
the matrix method to the performance and physicality of the more rigorous
approach.Comment: v1 :11 pages, 5 figures. v2: title change requested by referee, and
other corrections/clarifications found during review. v3: final tweaks
suggested during review + move from revtex to jhep styl
Population Growth and Decline in City Neighborhoods
Analyzes how neighborhoods in the nation's largest cities grew and declined in the 1990s and how those results compared with patterns of change in the 1980s, based on data from the U.S. Census and the Neighborhood Change Database
Concentrated Poverty: Dynamics of Change
Compares metropolitan census tracts that improved with respect to poverty in the 1990s with those that worsened, looking at the racial composition of both types and in different types of metropolitan areas nationally
Localization and freezing of a Gaussian chain in a quenched random potential
The Gaussian chain in a quenched random potential (which is characterized by
the disorder strength ) is investigated in the - dimensional space
by the replicated variational method. The general expression for the free
energy within so called one - step - replica symmetry breaking (1 - RSB)
scenario has been systematically derived. We have shown that the replica
symmetrical (RS) limit of this expression can describe the chain center of mass
localization and collapse. The critical disorder when the chain becomes
localized scales as (where is the length
of the Kuhn segment length and is the chain length) whereas the chain
gyration radius . The freezing of
the internal degrees of freedom follows to the 1-RSB - scenario and is
characterized by the beads localization length . It was
demonstrated that the solution for appears as a metastable
state at and behaves similarly to the corresponding frozen
states in heteropolymers or in - spin random spherical model.Comment: 18 pages, 6 figures, submitted to J. Chem. Phy
Possible Suppression of Resonant Signals for Split-UED by Mixing at the LHC?
The mixing of the imaginary parts of the transition amplitudes of nearby
resonances via the breakdown of the Breit-Wigner approximation has been shown
to lead to potentially large modifications in the signal rates for new physics
at colliders. In the case of suppression, this effect may be significant enough
to lead to some new physics signatures being initially missed in searches at,
e.g., the LHC. Here we explore the influence of this `width mixing' on the
production of the nearly degenerate, level-2 Kaluza-Klein (KK) neutral gauge
bosons present in Split-UED. We demonstrate that in this particular case large
cross section modifications in the resonance region are necessarily absent and
explain why this is so based on the group theoretical structure of the SM.Comment: 10 pages, 2 figures; discussion and references adde
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