22,455 research outputs found
Don\u27t Repeat a Word of This!
Can you write a composition of 100 words or more without repeating a single word? Without using even an a or an an or a the more than once
Resolvent Positive Linear Operators Exhibit the Reduction Phenomenon
The spectral bound, s(a A + b V), of a combination of a resolvent positive
linear operator A and an operator of multiplication V, was shown by Kato to be
convex in b \in R. This is shown here, through an elementary lemma, to imply
that s(a A + b V) is also convex in a > 0, and notably, \partial s(a A + b V) /
\partial a <= s(A) when it exists. Diffusions typically have s(A) <= 0, so that
for diffusions with spatially heterogeneous growth or decay rates, greater
mixing reduces growth. Models of the evolution of dispersal in particular have
found this result when A is a Laplacian or second-order elliptic operator, or a
nonlocal diffusion operator, implying selection for reduced dispersal. These
cases are shown here to be part of a single, broadly general, `reduction'
phenomenon.Comment: 7 pages, 53 citations. v.3: added citations, corrections in
introductory definitions. v.2: Revised abstract, more text, and details in
new proof of Lindqvist's inequalit
Newly identified lines in NeI isoelectronic sequences
Grazing-incidence spectrometer and low inductance spark source used to study lines of high degrees of ionization of Sc, Ti, and
A role for the developing lexicon in phonetic category acquisition
Infants segment words from fluent speech during the same period when they are learning phonetic categories, yet accounts of phonetic category acquisition typically ignore information about the words in which sounds appear. We use a Bayesian model to illustrate how feedback from segmented words might constrain phonetic category learning by providing information about which sounds occur together in words. Simulations demonstrate that word-level information can successfully disambiguate overlapping English vowel categories. Learning patterns in the model are shown to parallel human behavior from artificial language learning tasks. These findings point to a central role for the developing lexicon in phonetic category acquisition and provide a framework for incorporating top-down constraints into models of category learning
Probing a Very Narrow Boson with CDF and D0 Data
The CDF and D0 data of nearly 475 in the dilepton channel is
used to probe a recent class of models, Stueckelberg extensions of the Standard
Model (StSM), which predict a boson whose mass is of topological origin
with a very narrow decay width. A Drell-Yan analysis for dilepton production
via this shows that the current data put constraints on the parameter
space of the StSM. With a total integrated luminosity of ,
the very narrow can be discovered up to a mass of about 600 GeV. The StSM
will be very distinct since it can occur in the region where a
Randall-Sundrum graviton is excluded.Comment: 4 pages, 3 figure
The Bull's-Eye Effect as a Probe of
We compare the statistical properties of structures normal and transverse to
the line of sight which appear in theoretical N-body simulations of structure
formation, and seem also to be present in observational data from redshift
surveys. We present a statistic which can quantify this effect in a
conceptually different way from standard analyses of distortions of the
power-spectrum or correlation function. From tests with --body experiments,
we argue that this statistic represents a new and potentially powerful
diagnostic of the cosmological density parameter, .Comment: Minor revisions; final version accepted for publication in ApJ
Letters. Latex, 16 pages, including 3 figures. Higher resolution versions of
figures, including supplementary figures not included in the manuscript, are
available at: ftp://kusmos.phsx.ukans.edu/preprints/melott/omeg
- …