98,698 research outputs found
Bridging The Divide: How Business Ownership Can Help Close the Racial Wealth Gap
Our nation faces significant challenges addressing the growing racial wealth gap. This white paper, written by Joyce Klein, Director of FIELD at the Aspen Institute, outlines the role that business ownership can and does play in building wealth for people of color.Latinos and African Americans holder relatively low levels of business assets, contributing to their lower levels of wealth overall. Yet there are trends in the right direction: rates of business creation among these entrepreneurs are increasing, and now exceed those of whites. Particularly among African Americans, higher levels of college attainment combined with expanded contracting opportunities are enabling movement into more lucrative markets and sectors.While there are positive signs, low levels of personal wealth and challenges in accessing business credit continue to be primary factors limiting the growth of firms owned by Latinos and African Americans. Relatively high and growing levels of student debt further complicate the financial challenges faced by entrepreneurs of color. Lower levels of education among Latinos constrain their ability to move into higher-growth, higher-revenue sectors, and also affect the skills they bring to businesses they create.The white paper outlines short- and long-term recommendations to address the racial wealth gap through business ownership strategies. In the short-term, continuing and expanding efforts to increase access to capital, skills, networks, and markets will be needed to realize the promise that business ownership holds for addressing the racial wealth gap. In the long-term, universal policies to narrow the racial wealth gap -- such as those aimed at raising the quality of education, building savings, and increasing financial inclusion -- will be critical
Quantum theory of large amplitude collective motion and the Born-Oppenheimer method
We study the quantum foundations of a theory of large amplitude collective
motion for a Hamiltonian expressed in terms of canonical variables. In previous
work the separation into slow and fast (collective and non-collective)
variables was carried out without the explicit intervention of the Born
Oppenheimer approach. The addition of the Born Oppenheimer assumption not only
provides support for the results found previously in leading approximation, but
also facilitates an extension of the theory to include an approximate
description of the fast variables and their interaction with the slow ones.
Among other corrections, one encounters the Berry vector and scalar potential.
The formalism is illustrated with the aid of some simple examples, where the
potentials in question are actually evaluated and where the accuracy of the
Born Oppenheimer approximation is tested. Variational formulations of both
Hamiltonian and Lagrangian type are described for the equations of motion for
the slow variables.Comment: 29 pages, 1 postscript figure, preprint no UPR-0085NT. Latex + epsf
styl
Classical mappings of the symplectic model and their application to the theory of large-amplitude collective motion
We study the algebra Sp(n,R) of the symplectic model, in particular for the
cases n=1,2,3, in a new way. Starting from the Poisson-bracket realization we
derive a set of partial differential equations for the generators as functions
of classical canonical variables. We obtain a solution to these equations that
represents the classical limit of a boson mapping of the algebra. The
relationship to the collective dynamics is formulated as a theorem that
associates the mapping with an exact solution of the time-dependent Hartree
approximation. This solution determines a decoupled classical symplectic
manifold, thus satisfying the criteria that define an exactly solvable model in
the theory of large amplitude collective motion. The models thus obtained also
provide a test of methods for constructing an approximately decoupled manifold
in fully realistic cases. We show that an algorithm developed in one of our
earlier works reproduces the main results of the theorem.Comment: 23 pages, LaTeX using REVTeX 3.
Numerical study of blow-up and stability of line solitons for the Novikov-Veselov equation
We study numerically the evolution of perturbed Korteweg-de Vries solitons
and of well localized initial data by the Novikov-Veselov (NV) equation at
different levels of the "energy" parameter . We show that as , NV behaves, as expected, similarly to its formal limit, the
Kadomtsev-Petviashvili equation. However at intermediate regimes, i.e. when is not very large, more varied scenarios are possible, in particular,
blow-ups are observed. The mechanism of the blow-up is studied
Further application of a semi-microscopic core-particle coupling method to the properties of Gd155,157, and Dy159
In a previous paper a semi-microscopic core-particle coupling method that
includes the conventional strong coupling core-particle model as a limiting
case, was applied to spectra and electromagnetic properties of several
well-deformed odd nuclei. This work, coupled a large single-particle space to
the ground state bands of the neighboring even cores. In this paper, we
generalize the theory to include excited bands of the cores, such as beta and
gamma bands, and thereby show that the resulting theory can account for the
location and structure of all bands up to about 1.5 MeV.Comment: 15 pages including 9 figure(postscript), submitted to Phys.Rev.
Stability of the proton-to-electron mass ratio
We report a limit on the fractional temporal variation of the
proton-to-electron mass ratio as, obtained by comparing the frequency of a
rovibrational transition in SF6 with the fundamental hyperfine transition in
Cs. The SF6 transition was accessed using a CO2 laser to interrogate spatial
2-photon Ramsey fringes. The atomic transition was accessed using a primary
standard controlled with a Cs fountain. This result is direct and model-free
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