1,203 research outputs found
Consolidation, technology, and the changing structure of banks' small business lending
The U.S. banking industry continues to consolidate, with large, complex banking organizations becoming more important. Traditionally, these institutions have not emphasized small business lending. On the other hand, technological advances, particularly credit scoring models, make it easier for banks to extend small business credit. To see what effects these influences might have generated on small business lending, David Ely and Kenneth Robinson explore the small business lending patterns at U.S. banks from 1994 through 1999. They find that larger banks are increasing their market share, most noticeably in the smallest segment of the small business loan market. The authors also present evidence that the size of the average small business loan has declined, especially at larger organizations, and that the gap in lending focus on the smallest small business loans has narrowed between small and large banks. These trends are consistent with increasing use of credit scoring models.Credit ; Credit scoring systems
The determinants of the wealth effects of banks' expanded securities powers
After several unsuccessful attempts by Congress to repeal Glass-Steagall restrictions on banks, the Federal Reserve more than doubled the revenue that commercial banking organizations' securities subsidiaries may earn from certain securities activities. The wealth effects associated with this event for a sample of publicly traded banking organizations are examined. We find evidence that indicates the revenue limit resulted in a less-than-optimal mix of activities for securities subsidiaries. However, subsequent merger activity that could have been generated by the revenue increase was not viewed favorably by investors.Securities
Probing CDM cosmology with the Evolutionary Map of the Universe survey
The Evolutionary Map of the Universe (EMU) is an all-sky survey in
radio-continuum which uses the Australian SKA Pathfinder (ASKAP). Using galaxy
angular power spectrum and the integrated Sachs-Wolfe effect, we study the
potential of EMU to constrain models beyond CDM (i.e., local
primordial non-Gaussianity, dynamical dark energy, spatial curvature and
deviations from general relativity), for different design sensitivities. We
also include a multi-tracer analysis, distinguishing between star-forming
galaxies and galaxies with an active galactic nucleus, to further improve EMU's
potential. We find that EMU could measure the dark energy equation of state
parameters around 35\% more precisely than existing constraints, and that the
constraints on and modified gravity parameters will improve up to
a factor with respect to Planck and redshift space distortions
measurements. With this work we demonstrate the promising potential of EMU to
contribute to our understanding of the Universe.Comment: 15 pages (29 with references and appendices), 6 figures and 10
tables. Matches the published version. Minimal changes from previous versio
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Fast Moment Estimation in Data Streams in Optimal Space
We give a space-optimal streaming algorithm with update time for approximating the pth frequency moment, 0 < p < 2, of a length-n vector updated in a data stream up to a factor of . This provides a nearly exponential improvement over the previous space optimal algorithm of [Kane-Nelson-Woodruff, SODA 2010], which had update time . When combined with the work of [Harvey-Nelson-Onak, FOCS 2008], we also obtain the first algorithm for entropy estimation in turnstile streams which simultaneously achieves near-optimal space and fast update time.Engineering and Applied Science
Probing CDM cosmology with the Evolutionary Map of the Universe survey
The Evolutionary Map of the Universe (EMU) is an all-sky survey in
radio-continuum which uses the Australian SKA Pathfinder (ASKAP). Using galaxy
angular power spectrum and the integrated Sachs-Wolfe effect, we study the
potential of EMU to constrain models beyond CDM (i.e., local
primordial non-Gaussianity, dynamical dark energy, spatial curvature and
deviations from general relativity), for different design sensitivities. We
also include a multi-tracer analysis, distinguishing between star-forming
galaxies and galaxies with an active galactic nucleus, to further improve EMU's
potential. We find that EMU could measure the dark energy equation of state
parameters around 35\% more precisely than existing constraints, and that the
constraints on and modified gravity parameters will improve up to
a factor with respect to Planck and redshift space distortions
measurements. With this work we demonstrate the promising potential of EMU to
contribute to our understanding of the Universe.Comment: 15 pages (29 with references and appendices), 6 figures and 10
tables. Matches the published version. Minimal changes from previous versio
A Cauchy-Dirac delta function
The Dirac delta function has solid roots in 19th century work in Fourier
analysis and singular integrals by Cauchy and others, anticipating Dirac's
discovery by over a century, and illuminating the nature of Cauchy's
infinitesimals and his infinitesimal definition of delta.Comment: 24 pages, 2 figures; Foundations of Science, 201
Ten Misconceptions from the History of Analysis and Their Debunking
The widespread idea that infinitesimals were "eliminated" by the "great
triumvirate" of Cantor, Dedekind, and Weierstrass is refuted by an
uninterrupted chain of work on infinitesimal-enriched number systems. The
elimination claim is an oversimplification created by triumvirate followers,
who tend to view the history of analysis as a pre-ordained march toward the
radiant future of Weierstrassian epsilontics. In the present text, we document
distortions of the history of analysis stemming from the triumvirate ideology
of ontological minimalism, which identified the continuum with a single number
system. Such anachronistic distortions characterize the received interpretation
of Stevin, Leibniz, d'Alembert, Cauchy, and others.Comment: 46 pages, 4 figures; Foundations of Science (2012). arXiv admin note:
text overlap with arXiv:1108.2885 and arXiv:1110.545
Cosmology with the Highly Redshifted 21cm Line
In addition to being a probe of Cosmic Dawn and Epoch of Reionization
astrophysics, the 21cm line at is also a powerful way to constrain
cosmology. Its power derives from several unique capabilities. First, the 21cm
line is sensitive to energy injections into the intergalactic medium at high
redshifts. It also increases the number of measurable modes compared to
existing cosmological probes by orders of magnitude. Many of these modes are on
smaller scales than are accessible via the CMB, and moreover have the advantage
of being firmly in the linear regime (making them easy to model theoretically).
Finally, the 21cm line provides access to redshifts prior to the formation of
luminous objects. Together, these features of 21cm cosmology at provide
multiple pathways toward precise cosmological constraints. These include the
"marginalizing out" of astrophysical effects, the utilization of redshift space
distortions, the breaking of CMB degeneracies, the identification of signatures
of relative velocities between baryons and dark matter, and the discovery of
unexpected signs of physics beyond the CDM paradigm at high redshifts.Comment: Science white paper submitted to Decadal 2020 surve
Leibniz's Infinitesimals: Their Fictionality, Their Modern Implementations, And Their Foes From Berkeley To Russell And Beyond
Many historians of the calculus deny significant continuity between
infinitesimal calculus of the 17th century and 20th century developments such
as Robinson's theory. Robinson's hyperreals, while providing a consistent
theory of infinitesimals, require the resources of modern logic; thus many
commentators are comfortable denying a historical continuity. A notable
exception is Robinson himself, whose identification with the Leibnizian
tradition inspired Lakatos, Laugwitz, and others to consider the history of the
infinitesimal in a more favorable light. Inspite of his Leibnizian sympathies,
Robinson regards Berkeley's criticisms of the infinitesimal calculus as aptly
demonstrating the inconsistency of reasoning with historical infinitesimal
magnitudes. We argue that Robinson, among others, overestimates the force of
Berkeley's criticisms, by underestimating the mathematical and philosophical
resources available to Leibniz. Leibniz's infinitesimals are fictions, not
logical fictions, as Ishiguro proposed, but rather pure fictions, like
imaginaries, which are not eliminable by some syncategorematic paraphrase. We
argue that Leibniz's defense of infinitesimals is more firmly grounded than
Berkeley's criticism thereof. We show, moreover, that Leibniz's system for
differential calculus was free of logical fallacies. Our argument strengthens
the conception of modern infinitesimals as a development of Leibniz's strategy
of relating inassignable to assignable quantities by means of his
transcendental law of homogeneity.Comment: 69 pages, 3 figure
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