125,370 research outputs found
Lessons from the crisis
A lot happened even before the perceived beginning of this crisis in 2007, so although the events are recent, I will give an overview from a US perspective of the period from 2001 to date, in our search for the lessons to be learned. Much of it is probably familiar, but worth revisiting. I will break this necessarily simplified account into 3 stages: first, a look at the key factors that led to the increasing riskiness of US home mortgages; second, how those risks were transmitted as securities from US housing lenders to institutional investors around the globe; and third, how those risks led to huge losses and created a credit crunch that moved the impact from the financial economy to the real economy and produced a severe recession. Then we will have a factual foundation for deriving the lessons that ought to be taken away from this very expensive experience
Uniform analytic approximation of Wigner rotation matrices
We derive the leading asymptotic approximation, for low angle {\theta}, of
the Wigner rotation matrix elements , uniform in
and . The result is in terms of a Bessel function of integer order. We
numerically investigate the error for a variety of cases and find that the
approximation can be useful over a significant range of angles. This
approximation has application in the partial wave analysis of wavepacket
scattering.Comment: 8 pages, 5 figure
Natural Philosophy or Science in Premodern Epistemic Regimes? The Case of the Astrology of Albert the Great and Galileo Galilei
Scholarly attempts to analyze the history of science sometime suffer from an imprecise use of terms. In order to understand accurately how science has developed and from where it draws its roots, researchers should be careful to recognize that epistemic regimes change over time and acceptable forms of knowledge production are contingent upon the hegemonic discourse informing the epistemic regime of any given period. In order to understand the importance of this point, I apply the techniques of historical epistemology to an analysis of the place of the study of astrology in the medieval and early modern periods alongside a discussion of the “language games” of these period as well as the role of the “archeology of knowledge” in uncovering meaning in our study of the past. In sum, I argue that the term “science” should never be used when studying approaches to knowledge formation prior to the seventeenth century
Prediction of deviations from the Rutherford formula for low-energy Coulomb scattering of wavepackets
We calculate the nonrelativistic scattering of a wavepacket from a Coulomb
potential and find deviations from the Rutherford formula in all cases. These
generally occur only at low scattering angles, where they would be obscured by
the part of the incident beam that emerges essentially unscattered. For a model
experiment, the scattering of helium nuclei from a thin gold foil, we find the
deviation region is magnified for low incident energies (in the keV range), so
that a large shadow zone of low probability around the forward direction is
expected to be measurable.
From a theoretical perspective, the use of wavepackets makes partial wave
analysis applicable to this infinite-range potential. It allows us to calculate
the everywhere finite probability for a wavepacket to wavepacket transition and
to relate this to the differential cross section. Time delays and advancements
in the detection probabilities can be calculated. We investigate the optical
theorem as applied to this special case.Comment: 21 pages, 8 figures. This version contains clarifications and
additional results compared to the previous version. The paper has been
accepted for publication in J.Phys.
Arkansas Bulletin of Water Research - Issue 2018
The Arkansas Bulletin of Water Research is a publication of the Arkansas Water Resources Center (AWRC). This bulletin is produced in an effort to share water research relevant to Arkansas water stakeholders in an easily searchable and aesthetically engaging way. This is the second publication of the bulletin and will be published annually. The submission of a paper to this bulletin is appropriate for topics at all related to water resources, by anyone conducting water research or investigations. This includes but is not limited to university researchers, consulting firms, watershed groups, and other agencies. Prospective authors should read the “Introduction to the Arkanasas Bulletin of Water Research” contained within this publication and should refer to the AWRC website for additional infromation.
https://arkansas-water-center.uark.edu
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