9,227 research outputs found
The gravity lagrangian according to solar system experiments
In this work we show that the gravity lagrangian f(R) at relatively low
curvatures in both metric and Palatini formalisms is a bounded function that
can only depart from the linearity within the limits defined by well known
functions. We obtain those functions by analysing a set of inequalities that
any f(R) theory must satisfy in order to be compatible with laboratory and
solar system observational constraints. This result implies that the recently
suggested f(R) gravity theories with nonlinear terms that dominate at low
curvatures are incompatible with observations and, therefore, cannot represent
a valid mechanism to justify the cosmic speed-up.Comment: 4 pages, revtex
Capture of non-relativistic particles in eccentric orbits by a Kerr black hole
We obtain approximate analytic expressions for the critical value of the
total angular momentum of a non-relativistic test particle moving in the Kerr
geometry, such that it will be captured by the black hole. The expressions
apply to arbitrary orbital inclinations, and are accurate over the entire range
of angular momentum for the Kerr black hole. The expressions can be easily
implemented in N-body simulations of the evolution of star clusters around
massive galactic black holes, where such captures play an important role.Comment: 8 pages, 1 figure, published versio
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Census Snapshot: Indiana
Using data from the U.S. Census Bureau, this report provides demographic and economic information about same-sex couples and same-sex couples raising children in Indiana. We compare same-sex "unmarried partners," which the Census Bureau defines as an unmarried couple who "shares living quarters and has a close personal relationship," to different-sex married couples in Indiana
Census Snapshot: Ohio
Using data from the U.S. Census Bureau, this report provides demographic and economic information about same-sex couples and same-sex couples raising children in Ohio. We compare same-sex "unmarried partners," which the Census Bureau defines as an unmarried couple who "shares living quarters and has a close personal relationship," to different-sex married couples in Ohio
The Averaged Periodogram Estimator for a Power Law in Coherency
We prove the consistency of the averaged periodogram estimator (APE) in
two new cases. First, we prove that the APE is consistent for negative
memory parameters, after suitable tapering. Second, we prove that the
APE is consistent for a power law in the cross-spectrum and therefore
for a power law in the coherency, provided that sufficiently many
frequencies are used in estimation. Simulation evidence suggests that
the lower bound on the number of frequencies is a necessary condition
for consistency. For a Taylor series approximation to the estimator of
the power law in the cross-spectrum, we consider the rate of
convergence, and obtain a central limit theorem under suitable
regularity conditions.J.P. Morgan Chase and Co. and New York UniversityStatistics Working Papers Serie
Computationally Efficient Gaussian Maximum Likelihood Methods for Vector ARFIMA Models
In this paper, we discuss two distinct multivariate time series models that extend the univariate ARFIMA model. We describe algorithms for computing the covariances of each model, for computing the quadratic form and approximating the determinant for maximum likelihood estimation, and for simulating from each model. We compare the speed and accuracy of each algorithm to existing methods and measure the performance of the maximum likelihood estimator compared to existing methods. We also fit models to data on unemployment and inflation in the United States, to data on goods and services inflation in the United States, and to data about precipitation in the Great Lakes.Statistics Working Papers Serie
Response to the Letter to the Editor
This paper has attracted interest around the world from the media (both TV
and newspapers). In addition, we have received letters, emails and telephone
calls. One of our favorites was a voicemail message asking us to return a call
to Australia at which point we would learn who really killed JFK. We welcome
the opportunity to respond to the letter to the editor from Mr. Fiorentino. Mr.
Fiorentino claims that our ``statement relating to the likelihood of a second
assassin based on the premise of three or more separate bullets is demonstrably
false.'' In response we would like to simply quote from page 327 of Gerald
Posner's book Case Closed, one of the most well known works supporting the
single assassin theory: ``If Connally was hit by another bullet, it had to be
fired from a second shooter, since the Warren Commission's own reconstructions
showed that Oswald could not have operated the bolt and refired in 1.4
seconds.'' Mr. Fiorentino also claims that the ``second fatal flaw is the use
of a rather uncomplicated formula based on Bayes Theorem.'' Let denote the
evidence and denote the theory that there were just two bullets (and hence
a single shooter). We used Bayes Theorem to hypothetically calculate
from and the prior probability . In order to make ten
times more likely than , the ratio of the prior probabilities
[i.e., ] would have to be greater than 15. Thus, we again
conclude that this casts serious doubt on Dr. Guinn's conclusion that the
evidence supported just two bullets. Sadly, this is far from the first time
that probability has been misunderstood and/or misapplied in a case of public
interest. A notable British example is the Clark case. See Nobles and Schiff
(2005) for details. Finally, we welcome and, in fact, encourage members of the
scientific community to provide alternative analyses of the data.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS154 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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