303 research outputs found
Stochastic modeling for the COMET-assay
We present a stochastic model for single cell gel electrophoresis (COMET-assay) data. Essential is the use of point process structures, renewal theory and reduction to intensity histograms for further data analysis
Parsimonious Segmentation of Time Series' by Potts Models
Typical problems in the analysis of data sets like time-series or images crucially rely on the extraction of primitive features based on segmentation. Variational approaches are a popular and convenient framework in which such problems can be studied. We focus on Potts models as simple nontrivial instances. The discussion proceeds along two data sets from brain mapping and functional genomics
The Spatial Product of Arveson Systems is Intrinsic
We prove that the spatial product of two spatial Arveson systems is
independent of the choice of the reference units. This also answers the same
question for the minimal dilation the Powers sum of two spatial CP-semigroups:
It is independent up to cocycle conjugacy
Subsystems of Fock Need Not Be Fock: Spatial CP-Semigroups
We show that a product subsystem of a time ordered system (that is, a product
system of time ordered Fock modules), though type I, need not be isomorphic to
a time ordered product system. In that way, we answer an open problem in the
classification of CP-semigroups by product systems. We define spatial strongly
continuous CP-semigroups on a unital C*-algebra and characterize them as those
that have a Christensen-Evans generator.Comment: Revised and enlarged version, to appear in Proc. Amer. Math. So
An Elementary Rigorous Introduction to Exact Sampling
We introduce coupling from the past, a recently developed method for exact sampling from a given distribution. Focus is on rigour and thorough proofs. We stay on an elementary level which requires little or no prior knowledge from probability theory. This should fill an obvious gap between innumerable intuitive and incomplete reviews, and few precise derivations on an abstract level
Scale space consistency of piecewise constant least squares estimators -- another look at the regressogram
We study the asymptotic behavior of piecewise constant least squares
regression estimates, when the number of partitions of the estimate is
penalized. We show that the estimator is consistent in the relevant metric if
the signal is in , the space of c\`{a}dl\`{a}g functions equipped
with the Skorokhod metric or equipped with the supremum metric.
Moreover, we consider the family of estimates under a varying smoothing
parameter, also called scale space. We prove convergence of the empirical scale
space towards its deterministic target.Comment: Published at http://dx.doi.org/10.1214/074921707000000274 in the IMS
Lecture Notes Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
Early stage phase separation of AlCoCr<sub>0.75</sub>Cu<sub>0.5</sub>FeNi high-entropy powder at the nanoscale
High entropy alloys are generally considered to be single phase material.
This state is, however, typically a non-equilibrium state after fabrication at
high cooling rates. Phase constitution after fabrication or heat treatment is
mostly known for isothermal annealing only and for casts as well as rapidly
quenched alloys. Knowledge on early phase separation stages of high entropy
alloys and their mechanisms are missing so far. Here, we present results on
phase separation at intermediate cooling rates, by characterization of gas
atomized powder of the AlCoCr0.75Cu0.5FeNi alloy. Although investigation by
X-ray diffraction and Electron Backscatter Diffraction indicates a single-phase
nature of the powder particles, aberration-corrected scanning transmission
electron microscopy and atom probe tomography reveal a nanoscale phase
separation into Ni-Al-rich B2 and Fe-Cr-rich A2 regions as well as a high
number density of 3.1x1024 Cu-rich clusters per m3 in the B2 matrix. The
observed phase separation and cluster formation are linked to spinodal
decomposition and nucleation processes, respectively. The study highlights that
adequate characterization techniques need to be chosen when making statements
about phase stability and structural evolution in compositionally complex
alloys.Comment: 33 pages, 12 figure
Time-Varying Fine-Structure Constant Requires Cosmological Constant
Webb et al. presented preliminary evidence for a time-varying fine-structure
constant. We show Teller's formula for this variation to be ruled out within
the Einstein-de Sitter universe, however, it is compatible with cosmologies
which require a large cosmological constant.Comment: 3 pages, no figures, revtex, to be published in Mod. Phys. Lett.
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