9,232 research outputs found
A Hierarchical Bayesian Model of Pitch Framing
Since the advent of high-resolution pitch tracking data (PITCHf/x), many in
the sabermetrics community have attempted to quantify a Major League Baseball
catcher's ability to "frame" a pitch (i.e. increase the chance that a pitch is
called as a strike). Especially in the last three years, there has been an
explosion of interest in the "art of pitch framing" in the popular press as
well as signs that teams are considering framing when making roster decisions.
We introduce a Bayesian hierarchical model to estimate each umpire's
probability of calling a strike, adjusting for pitch participants, pitch
location, and contextual information like the count. Using our model, we can
estimate each catcher's effect on an umpire's chance of calling a strike.We are
then able to translate these estimated effects into average runs saved across a
season. We also introduce a new metric, analogous to Jensen, Shirley, and
Wyner's Spatially Aggregate Fielding Evaluation metric, which provides a more
honest assessment of the impact of framing
Towards the Control over Electroweak Penguins in Nonleptonic B-Decays
We present strategies for determining electroweak penguins from experimental
data. Using the CKM-angle as one of our central inputs and making some
reasonable approximations, we show that the electroweak
penguin amplitude can be determined in a two-step procedure involving i)
BR, BR, BR and ii) either
BR, BR or \acp(t) of the mode
. The determination employing the transitions is not
affected by -breaking effects. Relating the
electroweak penguin amplitude to the case through
symmetry arguments, we are in a position to estimate the electroweak penguin
uncertainty affecting the extraction of the CKM-angle by using isospin
relations among decays. Our results allow in principle the
determination of CKM-phases in a variety of -decays.Comment: 14 pages, LaTeX, Figures not include
Least squares approximations of measures via geometric condition numbers
For a probability measure on a real separable Hilbert space, we are
interested in "volume-based" approximations of the d-dimensional least squares
error of it, i.e., least squares error with respect to a best fit d-dimensional
affine subspace. Such approximations are given by averaging real-valued
multivariate functions which are typically scalings of squared (d+1)-volumes of
(d+1)-simplices. Specifically, we show that such averages are comparable to the
square of the d-dimensional least squares error of that measure, where the
comparison depends on a simple quantitative geometric property of it. This
result is a higher dimensional generalization of the elementary fact that the
double integral of the squared distances between points is proportional to the
variance of measure. We relate our work to two recent algorithms, one for
clustering affine subspaces and the other for Monte-Carlo SVD based on volume
sampling
OH Maser sources in W49N: probing differential anisotropic scattering with Zeeman pairs
Our analysis of a VLBA 12-hour synthesis observations of the OH masers in
W49N has provided detailed high angular-resolution images of the maser sources,
at 1612, 1665 and 1667 MHz. The images, of several dozens of spots, reveal
anisotropic scatter broadening; with typical sizes of a few tens of
milli-arc-seconds and axial ratios between 1.5 to 3. The image position angles
oriented perpendicular to the galactic plane are interpreted in terms of
elongation of electron-density irregularities parallel to the galactic plane,
due to a similarly aligned local magnetic field. However, we find the apparent
angular sizes on the average a factor of 2.5 less than those reported by Desai
et al., indicating significantly less scattering than inferred earlier. The
average position angle of the scattered broadened images is also seen to
deviate significantly (by about 10 degrees) from that implied by the magnetic
field in the Galactic plane. More intriguingly, for a few Zeeman pairs in our
set, we find significant differences in the scatter broadened images for the
two hands of polarization, even when apparent velocity separation is less than
0.1 km/s. Here we present the details of our observations and analysis, and
discuss the interesting implications of our results for the intervening
anisotropic magneto-ionic medium, as well as a comparison with the expectations
based on earlier work.Comment: 5 pages, 3 figures, submitted to the Proceedings of the IAU Symposium
287: "Cosmic masers - from OH to H0
CP Violation in a Multi-Higgs Doublet Model
We study CP violation in a multi-Higgs doublet model based on a horizontal symmetry. We consider two mechanisms for CP violation in this
model: a) CP violation due to complex Yukawa couplings; and b) CP violation due
to scalar-pseudoscalar mixings. We find that the predictions for
, CP violation in B decays and the electric dipole moments
of neutron and electron are different between these two mechanisms. These
predictions are also dramatically different from the minimal Standard Model
predictions.Comment: 17 pages + one figure, Revtex. Talk presented by Deshpande at the
Conference WHEPP-3, December 199
Rail transit fare collection: Policy and technology assessment
The impact of fare policies and fare structure on the selection of equipment was investigated, fare collection systems are described, hardware and technology related problems are documented, and the requirements of a fare collection simulation model are outlined. Major findings include: (1) a wide variation in the fare collection systems and equipment, caused primarily by historical precedence; (2) the reliability of AFC equipment used at BART and WMATA discouraged other properties from considering use of similar equipment; (3) existing equipment may not meet the fare collection needs of properties in the near future; (4) the cost of fare collection operation and maintenance is high; and (5) the relatively small market in fare collection equipment discourages new product development by suppliers. Recommendations for fare collection R&D programs include development of new hardware to meet rail transit needs, study of impacts of alternate fare policies increased communication among policymakers, and consensus on fare policy issues
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