7,924 research outputs found
Bonus scaling and BCFW in N=7 supergravity
In search of natural building blocks for supergravity amplitudes, a tentative
criteria is term-by-term bonus z^-2 large momentum scaling. For a given choice
of deformation legs, we present such an expansion in the form of a BCFW
representation in N=7 supergravity based on a special shift. We will show that
this improved scaling behavior, with respect to the fully N=8 representation,
is due to its automatic incorporation of the so called bonus relations.Comment: 16 pages, 2 figure
Optimal Tests of Treatment Effects for the Overall Population and Two Subpopulations in Randomized Trials, using Sparse Linear Programming
We propose new, optimal methods for analyzing randomized trials, when it is
suspected that treatment effects may differ in two predefined subpopulations.
Such sub-populations could be defined by a biomarker or risk factor measured at
baseline. The goal is to simultaneously learn which subpopulations benefit from
an experimental treatment, while providing strong control of the familywise
Type I error rate. We formalize this as a multiple testing problem and show it
is computationally infeasible to solve using existing techniques. Our solution
involves a novel approach, in which we first transform the original multiple
testing problem into a large, sparse linear program. We then solve this problem
using advanced optimization techniques. This general method can solve a variety
of multiple testing problems and decision theory problems related to optimal
trial design, for which no solution was previously available. In particular, we
construct new multiple testing procedures that satisfy minimax and Bayes
optimality criteria. For a given optimality criterion, our new approach yields
the optimal tradeoff? between power to detect an effect in the overall
population versus power to detect effects in subpopulations. We demonstrate our
approach in examples motivated by two randomized trials of new treatments for
HIV
Corporate Governance and Market Valuation in China
This paper studies the relationship between the governance mechanisms and the market valuation of publicly listed firms in China empirically. We construct measures for corporate governance mechanisms and measures of market valuation for all publicly listed firms on the two stock markets in China by using data from the firm’s annual reports. We then investigate how the market-valuation variables are affected by the corporate governance variables while controlling for a number of factors commonly considered in market valuation analysis. A corporate governance index is also constructed to summarize the information contained in the corporate governance variables. The index is found to have statistically and economically significant effect on market valuation. The analysis indicates that investors pay a significant premium for well-governed firms in China, benefiting firms that improve their governance mechanisms.http://deepblue.lib.umich.edu/bitstream/2027.42/39949/3/wp564.pd
Effect of Earth's rotation on the trajectories of free-fall bodies in Equivalence Principle Experiment
Owing to Earth's rotation a free-fall body would move in an elliptical orbit
rather than along a straight line forward to the center of the Earth. In this
paper on the basis of the theory for spin-spin coupling between macroscopic
rotating bodies we study violation of the equivalence principle from
long-distance free-fall experiments by means of a rotating ball and a
non-rotating sell. For the free-fall time of 40 seconds, the difference between
the orbits of the two free-fall bodies is of the order of 10^{-9}cm which could
be detected by a SQUID magnetometer owing to such a magnetometer can be used to
measure displacements as small as 10^{-13} centimeters.Comment: 6 pages, 4 figure
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