1,363 research outputs found
Precise Estimation of Cosmological Parameters Using a More Accurate Likelihood Function
The estimation of cosmological parameters from a given data set requires a
construction of a likelihood function which, in general, has a complicated
functional form. We adopt a Gaussian copula and constructed a copula likelihood
function for the convergence power spectrum from a weak lensing survey. We show
that the parameter estimation based on the Gaussian likelihood erroneously
introduces a systematic shift in the confidence region, in particular for a
parameter of the dark energy equation of state w. Thus, the copula likelihood
should be used in future cosmological observations.Comment: 5 pages, 3 figures. Maches version published by the Physical Review
Letter
Intellectual Property Management in Health and Agricultural Innovation: A Handbook of Best Practices, Vol. 1
Prepared by and for policy-makers, leaders of public sector research establishments, technology transfer professionals, licensing executives, and scientists, this online resource offers up-to-date information and strategies for utilizing the power of both intellectual property and the public domain. Emphasis is placed on advancing innovation in health and agriculture, though many of the principles outlined here are broadly applicable across technology fields. Eschewing ideological debates and general proclamations, the authors always keep their eye on the practical side of IP management. The site is based on a comprehensive Handbook and Executive Guide that provide substantive discussions and analysis of the opportunities awaiting anyone in the field who wants to put intellectual property to work. This multi-volume work contains 153 chapters on a full range of IP topics and over 50 case studies, composed by over 200 authors from North, South, East, and West. If you are a policymaker, a senior administrator, a technology transfer manager, or a scientist, we invite you to use the companion site guide available at http://www.iphandbook.org/index.html The site guide distills the key points of each IP topic covered by the Handbook into simple language and places it in the context of evolving best practices specific to your professional role within the overall picture of IP management
A Hybrid Lagrangian Variation Method for Bose-Einstein Condensates in Optical Lattices
Solving the Gross--Pitaevskii (GP) equation describing a Bose--Einstein
condensate (BEC) immersed in an optical lattice potential can be a numerically
demanding task. We present a variational technique for providing fast, accurate
solutions of the GP equation for systems where the external potential exhibits
rapid varation along one spatial direction. Examples of such systems include a
BEC subjected to a one--dimensional optical lattice or a Bragg pulse. This
variational method is a hybrid form of the Lagrangian Variational Method for
the GP equation in which a hybrid trial wavefunction assumes a gaussian form in
two coordinates while being totally unspecified in the third coordinate. The
resulting equations of motion consist of a quasi--one--dimensional GP equation
coupled to ordinary differential equations for the widths of the transverse
gaussians. We use this method to investigate how an optical lattice can be used
to move a condensate non--adiabatically.Comment: 16 pages and 1 figur
Intellectual Property Management in Health and Agricultural Innovation: Executive Guide
Prepared by and for policy-makers, leaders of public sector research establishments, technology transfer professionals, licensing executives, and scientists, this online resource offers up-to-date information and strategies for utilizing the power of both intellectual property and the public domain. Emphasis is placed on advancing innovation in health and agriculture, though many of the principles outlined here are broadly applicable across technology fields. Eschewing ideological debates and general proclamations, the authors always keep their eye on the practical side of IP management. The site is based on a comprehensive Handbook and Executive Guide that provide substantive discussions and analysis of the opportunities awaiting anyone in the field who wants to put intellectual property to work. This multi-volume work contains 153 chapters on a full range of IP topics and over 50 case studies, composed by over 200 authors from North, South, East, and West. If you are a policymaker, a senior administrator, a technology transfer manager, or a scientist, we invite you to use the companion site guide available at http://www.iphandbook.org/index.html The site guide distills the key points of each IP topic covered by the Handbook into simple language and places it in the context of evolving best practices specific to your professional role within the overall picture of IP management
An information theoretic approach to statistical dependence: copula information
We discuss the connection between information and copula theories by showing
that a copula can be employed to decompose the information content of a
multivariate distribution into marginal and dependence components, with the
latter quantified by the mutual information. We define the information excess
as a measure of deviation from a maximum entropy distribution. The idea of
marginal invariant dependence measures is also discussed and used to show that
empirical linear correlation underestimates the amplitude of the actual
correlation in the case of non-Gaussian marginals. The mutual information is
shown to provide an upper bound for the asymptotic empirical log-likelihood of
a copula. An analytical expression for the information excess of T-copulas is
provided, allowing for simple model identification within this family. We
illustrate the framework in a financial data set.Comment: to appear in Europhysics Letter
Testing the Gaussian Copula Hypothesis for Financial Assets Dependences
Using one of the key property of copulas that they remain invariant under an
arbitrary monotonous change of variable, we investigate the null hypothesis
that the dependence between financial assets can be modeled by the Gaussian
copula. We find that most pairs of currencies and pairs of major stocks are
compatible with the Gaussian copula hypothesis, while this hypothesis can be
rejected for the dependence between pairs of commodities (metals).
Notwithstanding the apparent qualification of the Gaussian copula hypothesis
for most of the currencies and the stocks, a non-Gaussian copula, such as the
Student's copula, cannot be rejected if it has sufficiently many ``degrees of
freedom''. As a consequence, it may be very dangerous to embrace blindly the
Gaussian copula hypothesis, especially when the correlation coefficient between
the pair of asset is too high as the tail dependence neglected by the Gaussian
copula can be as large as 0.6, i.e., three out five extreme events which occur
in unison are missed.Comment: Latex document of 43 pages including 14 eps figure
Variable order Mittag-Leffler fractional operators on isolated time scales and application to the calculus of variations
We introduce new fractional operators of variable order on isolated time
scales with Mittag-Leffler kernels. This allows a general formulation of a
class of fractional variational problems involving variable-order difference
operators. Main results give fractional integration by parts formulas and
necessary optimality conditions of Euler-Lagrange type.Comment: This is a preprint of a paper whose final and definite form is with
Springe
Precision Determination of the Neutron Spin Structure Function g1n
We report on a precision measurement of the neutron spin structure function
using deep inelastic scattering of polarized electrons by polarized
^3He. For the kinematic range 0.014<x<0.7 and 1 (GeV/c)^2< Q^2< 17 (GeV/c)^2,
we obtain at an average . We find relatively large negative
values for at low . The results call into question the usual Regge
theory method for extrapolating to x=0 to find the full neutron integral
, needed for testing quark-parton model and QCD sum rules.Comment: 5 pages, 3 figures To be published in Phys. Rev. Let
Precision Measurement of the Weak Mixing Angle in Moller Scattering
We report on a precision measurement of the parity-violating asymmetry in
fixed target electron-electron (Moller) scattering: A_PV = -131 +/- 14 (stat.)
+/- 10 (syst.) parts per billion, leading to the determination of the weak
mixing angle \sin^2\theta_W^eff = 0.2397 +/- 0.0010 (stat.) +/- 0.0008 (syst.),
evaluated at Q^2 = 0.026 GeV^2. Combining this result with the measurements of
\sin^2\theta_W^eff at the Z^0 pole, the running of the weak mixing angle is
observed with over 6 sigma significance. The measurement sets constraints on
new physics effects at the TeV scale.Comment: 4 pages, 2 postscript figues, submitted to Physical Review Letter
Measurements of the -Dependence of the Proton and Neutron Spin Structure Functions g1p and g1n
The structure functions g1p and g1n have been measured over the range 0.014 <
x < 0.9 and 1 < Q2 < 40 GeV2 using deep-inelastic scattering of 48 GeV
longitudinally polarized electrons from polarized protons and deuterons. We
find that the Q2 dependence of g1p (g1n) at fixed x is very similar to that of
the spin-averaged structure function F1p (F1n). From a NLO QCD fit to all
available data we find at
Q2=5 GeV2, in agreement with the Bjorken sum rule prediction of 0.182 \pm
0.005.Comment: 17 pages, 3 figures. Submitted to Physics Letters
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