3,837 research outputs found
Finding Leverage Groups
A brief discussion of recent methods using the Hat Matrix for identifying leverage points, and clustering techniques for finding groups of data points is presented. The problem of identifying leverage groups is addressed, and a heuristic algorithm for identifying both leverage points and leverage groups is proposed. Semi-portable FORTRAN code implementing the algorithm, a sample terminal session, and a discussion of the terminal session are included.
A System of Subroutines For Iteratively Reweighted Least Squares Computations
A description of a system of subroutines to compute solutions to the iteratively reweighted least squares problem is presented. The weights are determined from the data and linear fit and are computed as functions of the scaled residuals. Iteratively reweighted least squares is a part of robust statistics where "robustness" means relative insensitivity to moderate departures from assumptions. The software for iteratively reweighted least squares is cast as semi-portable Fortran code whose performance is unaffected (in the sense that performance will not be degraded) by the computer or operating-system environment in which it is used. An [ell sub1] start and an [ell sub2] start are provided. Eight weight functions, a numerical rank determination, convergence criterion, and a stem-and-leaf display are included.
Heavy Quark Potential from Gauge/Gravity Duality: A Large D Analysis
The heavy-quark potential is calculated in the framework of gauge/gravity
duality using the large-D approximation, where D is the number of dimensions
transverse to the flux tube connecting a quark and an antiquark in a flat
D+2-dimensional spacetime. We find that in the large-D limit the leading
correction to the ground-state energy, as given by an effective Nambu-Goto
string, arises not from the heavy modes but from the behavior of the massless
modes in the vicinity of the quark and the antiquark. We estimate this
correction and find that it should be visible in the near-future lattice QCD
calculations of the heavy-quark potential.Comment: 22 pages, 5 Figures. v2: references added, typos corrected and, Sec.
4 rewritten with an expanded non-perturbative discussion of the corrections
to the Arvis potential arising from the massless modes near the boundary of
the qcd strin
One Divine Moment: The Account of the Asbury Revival of 1970
https://place.asburyseminary.edu/firstfruitsheritagematerial/1066/thumbnail.jp
Global clinical response in C ushing's syndrome patients treated with mifepristone
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106755/1/cen12332.pd
Probing Stellar Dynamics in Galactic Nuclei
Electromagnetic observations over the last 15 years have yielded a growing
appreciation for the importance of supermassive black holes (SMBH) to the
evolution of galaxies, and for the intricacies of dynamical interactions in our
own Galactic center. Here we show that future low-frequency gravitational wave
observations, alone or in combination with electromagnetic data, will open up
unique windows to these processes. In particular, gravitational wave detections
in the 10^{-5}-10^{-1} Hz range will yield SMBH masses and spins to
unprecedented precision and will provide clues to the properties of the
otherwise undetectable stellar remnants expected to populate the centers of
galaxies. Such observations are therefore keys to understanding the interplay
between SMBHs and their environments.Comment: 8 pages, Science white paper for the Astro2010 Decadal Surve
A (1,2) Heterotic String with Gauge Symmetry
We construct a (1,2) heterotic string with gauge symmetry and determine its
particle spectrum. This theory has a local N=1 worldsheet supersymmetry for
left movers and a local N=2 worldsheet supersymmetry for right movers and
describes particles in either two or three space-time dimensions. We show that
fermionizing the bosons of the compactified N=1 space leads to a particle
spectrum which has nonabelian gauge symmetry. The fermionic formulation of the
theory corresponds to a dimensional reduction of self dual Yang Mills. We also
give a worldsheet action for the theory and calculate the one-loop path
integral.Comment: 17 pages, added reference
Two-Impurity Kondo Model: Spin-Orbit Interactions and Entanglement
Motivated by proposals to employ RKKY-coupled spins as building blocks in a
solid-state quantum computer, we analyze how the RKKY interaction in a 2D
electron gas is influenced by spin-orbit interactions. Using a two-impurity
Kondo model with added Dresselhaus and Rashba spin-orbit interactions we find
that spin-rotational invariance of the RKKY interaction - essential for having
a well-controllable two-qubit gate - is restored when tuning the Rashba
coupling to have the same strength as the Dresselhaus coupling. We also discuss
the critical properties of the two-impurity Kondo model in the presence of
spin-orbit interactions, and extract the leading correction to the block
entanglement scaling due to these interactions.Comment: Proceedings of StatPhys 24 satellite conference in Hanoi; 9 pages, 4
figure
Probing the Planck Scale with Neutrino Oscillations
Quantum gravity "foam", among its various generic Lorentz non-invariant
effects, would cause neutrino mixing. It is shown here that, if the foam is
manifested as a nonrenormalizable effect at scale M, the oscillation length
generically decreases with energy as (E/M)^(-2). Neutrino observatories and
long-baseline experiments should have therefore already observed foam-induced
oscillations, even if M is as high as the Planck energy scale. The null
results, which can be further strengthened by better analysis of current data
and future experiments, can be taken as experimental evidence that Lorentz
invariance is fully preserved at the Planck scale, as is the case in critical
string theory.Comment: 11 pages, 2 figures. Final version published in PRD. 1 figure,
references, clarifications and explanations added. Results unchange
Effective Potential for the Conformal Sector of Quantum Gravity with Torsion
The effective potential which describes the conformal dynamics of quantum
gravity with torsion is discussed. The phase transitions induced by the
combination of torsion and curvature are investigated. The mechanism for fixing
the vacuum expectation values of the metric and torsion is presented.Comment: 9 pages, LaTeX, july 3
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