4,576 research outputs found
From finite sample to asymptotics: A geometric bridge for selection criteria in spline regression
This paper studies, under the setting of spline regression, the connection
between finite-sample properties of selection criteria and their asymptotic
counterparts, focusing on bridging the gap between the two. We introduce a
bias-variance decomposition of the prediction error, using which it is shown
that in the asymptotics the bias term dominates the variability term, providing
an explanation of the gap. A geometric exposition is provided for intuitive
understanding. The theoretical and geometric results are illustrated through a
numerical example.Comment: Published at http://dx.doi.org/10.1214/009053604000000841 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Stochastic modeling in nanoscale biophysics: Subdiffusion within proteins
Advances in nanotechnology have allowed scientists to study biological
processes on an unprecedented nanoscale molecule-by-molecule basis, opening the
door to addressing many important biological problems. A phenomenon observed in
recent nanoscale single-molecule biophysics experiments is subdiffusion, which
largely departs from the classical Brownian diffusion theory. In this paper, by
incorporating fractional Gaussian noise into the generalized Langevin equation,
we formulate a model to describe subdiffusion. We conduct a detailed analysis
of the model, including (i) a spectral analysis of the stochastic
integro-differential equations introduced in the model and (ii) a microscopic
derivation of the model from a system of interacting particles. In addition to
its analytical tractability and clear physical underpinning, the model is
capable of explaining data collected in fluorescence studies on single protein
molecules. Excellent agreement between the model prediction and the
single-molecule experimental data is seen.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS149 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Supersymmetric contributions to B --> K \pi branching ratio
We analyze the supersymmetric contributions to the B --> K\pi process. We
show that the simultaneous contributions from the penguin diagrams with
chargino and gluino in the loop could lead to a possible solution to the B -->
K \pi puzzle. Our result indicates that including the stringent constraint from
the b --> s \gamma branching ratio, the supersymmeteric models with light
right-handed top-squark and large mixing between second and third generation of
up and down squarks is the most preferred by the current experimental data.Comment: 4 pages, revtex, 2 figure
Attitude estimation of earth orbiting satellites by decomposed linear recursive filters
Attitude estimation of earth orbiting satellites (including Large Space Telescope) subjected to environmental disturbances and noises was investigated. Modern control and estimation theory is used as a tool to design an efficient estimator for attitude estimation. Decomposed linear recursive filters for both continuous-time systems and discrete-time systems are derived. By using this accurate estimation of the attitude of spacecrafts, state variable feedback controller may be designed to achieve (or satisfy) high requirements of system performance
Nonparametric inference of doubly stochastic Poisson process data via the kernel method
Doubly stochastic Poisson processes, also known as the Cox processes,
frequently occur in various scientific fields. In this article, motivated
primarily by analyzing Cox process data in biophysics, we propose a
nonparametric kernel-based inference method. We conduct a detailed study,
including an asymptotic analysis, of the proposed method, and provide
guidelines for its practical use, introducing a fast and stable regression
method for bandwidth selection. We apply our method to real photon arrival data
from recent single-molecule biophysical experiments, investigating proteins'
conformational dynamics. Our result shows that conformational fluctuation is
widely present in protein systems, and that the fluctuation covers a broad
range of time scales, highlighting the dynamic and complex nature of proteins'
structure.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS352 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
B_s^0 - bar{B}_s^0 Mixing and the B_s -> J/psi phi Asymmetry in Supersymmetric Models
We analyse supersymmetric contributions to B_s mixing and their impact on
mixing-induced CP asymmetries, using the mass insertion approximation. We
discuss in particular the correlation of SUSY effects in the CP asymmetries of
B_s -> J/psi phi and B_d -> phi K_S and find that the mass insertions dominant
in B_s mixing and B_d -> phi K_S are (delta_{23}^d)_{LL, RR} and
(delta_{23}^d)_{LR, RL}, respectively. We show that models with dominant
(delta_{23}^d)_{LR, RL} can accomodate a negative value of S_{phi K_S}, in
agreement with the BELLE measurement of that observable, but yield a B_s mixing
phase too small to be observed. On the other hand, models with dominant
(delta_{23}^d)_{LL, RR} predict sizeable SUSY contributions to both Delta M_s
and the mixing phase, but do not allow the asymmetry in B_d -> phi K_S to
become negative, except for small values of the average down squark mass,
which, in turn, entail a value of Delta M_s too large to be observed at the
Tevatron and the LHC. We conclude that the observation of B_s mixing at hadron
machines, together with the confirmation of a negative value of S_{phi K_S},
disfavours models with a single dominant mass insertion.Comment: 17 pages, 5 figure
Dispersive evaluation of the second-class amplitude in the standard model
We reevaluate the two form factors relevant for the second-class
decay mode, making systematic use of analyticity, unitarity, combined
with updated inputs to the NLO chiral constraints. We focus, in particular, on
the shape of the resonance peak which is a background-free signature of
a second-class current. Its dispersive construction requires the
scattering amplitude which we derive from a family of
Khuri-Treiman equations solutions constrained with accurate recent results on
the Dalitz plot.Comment: Presented at the 12th International workshop on Tau lepton physics
(TAU2012) in Nagoya, Japa
Equi-energy sampler with applications in statistical inference and statistical mechanics
We introduce a new sampling algorithm, the equi-energy sampler, for efficient
statistical sampling and estimation. Complementary to the widely used
temperature-domain methods, the equi-energy sampler, utilizing the
temperature--energy duality, targets the energy directly. The focus on the
energy function not only facilitates efficient sampling, but also provides a
powerful means for statistical estimation, for example, the calculation of the
density of states and microcanonical averages in statistical mechanics. The
equi-energy sampler is applied to a variety of problems, including exponential
regression in statistics, motif sampling in computational biology and protein
folding in biophysics.Comment: This paper discussed in: [math.ST/0611217], [math.ST/0611219],
[math.ST/0611221], [math.ST/0611222]. Rejoinder in [math.ST/0611224].
Published at http://dx.doi.org/10.1214/009053606000000515 in the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
A possible supersymmetric solution to the discrepancy between B -> \phi K_S and B -> \eta' K_S CP asymmetries
We present a possible supersymmetric solution to the discrepancy between the
observed mixing CP asymmetries in B -> \phi K_S and B -> \eta' K_S. We show
that due to the different parity in the final states of these processes, their
supersymmetric contributions from the R-sector have an opposite sign, which
naturally explain the large deviation between S_{\phi K_S} and S_{\eta' K_S}.
We also consider the proposed mechanisms to solve the puzzle of the observed
large branching ratio of B -> \eta' K and study their impact on S_{eta' K_S}.Comment: 4 pages, 2 figure
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