96,989 research outputs found

    Bridging The Divide: How Business Ownership Can Help Close the Racial Wealth Gap

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    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

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    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

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    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

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    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 E E . We show that as ∣E∣→∞ |E| \to \infty , NV behaves, as expected, similarly to its formal limit, the Kadomtsev-Petviashvili equation. However at intermediate regimes, i.e. when ∣E∣ | E | 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

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    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

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    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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