8,231 research outputs found
Nucleon-nucleon resonances at intermediate energies using a complex energy formalism
We apply our method of complex scaling, valid for a general class of
potentials, in a search for nucleon-nucleon S-matrix poles up to 2 GeV
laboratory kinetic energy. We find that the realistic potentials JISP16,
constructed from inverse scattering, and chiral field theory potentials NLO
and NLO support resonances in energy regions well above their fit
regions. In some cases these resonances have widths that are narrow when
compared with the real part of the S-matrix pole.Comment: 7 pages, 5 figures, 2 Table
Spin-injection Hall effect in a planar photovoltaic cell
Successful incorporation of the spin degree of freedom in semiconductor
technology requires the development of a new paradigm allowing for a scalable,
non-destructive electrical detection of the spin-polarization of injected
charge carriers as they propagate along the semiconducting channel. In this
paper we report the observation of a spin-injection Hall effect (SIHE) which
exploits the quantum-relativistic nature of spin-charge transport and which
meets all these key requirements on the spin detection. The two-dimensional
electron-hole gas photo-voltaic cell we designed to observe the SIHE allows us
to develop a quantitative microscopic theory of the phenomenon and to
demonstrate its direct application in optoelectronics. We report an
experimental realization of a non-magnetic spin-photovoltaic effect via the
SIHE, rendering our device an electrical polarimeter which directly converts
the degree of circular polarization of light to a voltage signal.Comment: 14 pages, 4 figure
Holographic Renormalization of general dilaton-axion gravity
We consider a very general dilaton-axion system coupled to Einstein-Hilbert
gravity in arbitrary dimension and we carry out holographic renormalization for
any dimension up to and including five dimensions. This is achieved by
developing a new systematic algorithm for iteratively solving the radial
Hamilton-Jacobi equation in a derivative expansion. The boundary term derived
is valid not only for asymptotically AdS backgrounds, but also for more general
asymptotics, including non-conformal branes and Improved Holographic QCD. In
the second half of the paper, we apply the general result to Improved
Holographic QCD with arbitrary dilaton potential. In particular, we derive the
generalized Fefferman-Graham asymptotic expansions and provide a proof of the
holographic Ward identities.Comment: 42 pages. v2: two references added. Version published in JHEP. v3:
fixed minor typos in eqs. (1.6), (2.3), (3.20), (A.3), (B.8), (B.12) and
(B.22
"A Path to Community Development, The Community Reinvestment Act, Lending Discrimination, and the Role of Community Development Banks"
The establishment of a system of federally regulated, for-profit, community development banks (CDBs) would help to fill the financial gap in areas inadequately served by traditional banks, requirements of the Community Reinvestment Act (CRA) notwithstanding. These organizations would be charged with delivering credit, payment, and savings opportunities and providing basic financing to households and small businesses in underserved areas. Such a system would not substitute for the CRA, but rather act as a supplement to current regulation. Proposed exemptions from CRA compliance for depository institutions that invest in the equity of a CDB would weaken the existing law by diluting the investment of the depository institution in its own particular community. Such proposals (under which "investment" has been defined to be as little as one-quarter of one percent of total assets) are not consistent with the spirit of the CRA and would negate the beneficial dialogue that takes place between the institution and the community in which it operates.
First-order transition in small-world networks
The small-world transition is a first-order transition at zero density of
shortcuts, whereby the normalized shortest-path distance undergoes a
discontinuity in the thermodynamic limit. On finite systems the apparent
transition is shifted by . Equivalently a ``persistence
size'' can be defined in connection with finite-size
effects. Assuming , simple rescaling arguments imply that
. We confirm this result by extensive numerical simulation in one to
four dimensions, and argue that implies that this transition is
first-order.Comment: 4 pages, 3 figures, To appear in Europhysics Letter
"An Alternative in Small Business Finance, Community-Based Factoring Companies and Small Business Lending"
According to Papadimitriou, Phillips, and Wray, at a time when small businesses are suffering from a credit crunch, "niche" financial institutions are filling the void left by more traditional sources of financing, such as commercial banks. The authors argue that the most important of these niche players are community-based factor companies, which are rapidly expanding from their client base in apparel and textiles to finance a range of firms in everything from electronics to health care. The purchase of accounts receivable by factors enhances the balance sheets of their clients, making it easier for the clients to obtain bank financing. Also, because factors are more interested in the creditworthiness of a client's customers than of the client itself, they are willing to extend loans in excess of collateral to rapidly growing businesses. Because factors are becoming an increasingly important source of financing for small and start-up businesses, the authors propose that factors be encouraged to play a broader role in financing firms in distressed communities by (1) making some factors eligible for funding and assistance under legislation regulating community development financial institutions and (2) by allowing investments by banks in factors to count toward compliance under the Community Reinvestment Act.
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