3,858 research outputs found
Towards a statement of the S-adic conjecture through examples
The -adic conjecture claims that there exists a condition such that a
sequence has a sub-linear complexity if and only if it is an -adic sequence
satisfying Condition for some finite set of morphisms. We present an
overview of the factor complexity of -adic sequences and we give some
examples that either illustrate some interesting properties or that are
counter-examples to what could be believed to be "a good Condition ".Comment: 2
Fraction of the radial velocity stable stars in the early observations of the Grid Giant Star Survey
The GGSS is a partially-filled, all-sky survey to identify K-giant stars with
low level of RV-variability. We study histograms of the radial velocity (RV)
variability obtained in the early phase of the Grid Giant Star Survey (GGSS,
Bizyaev et al., 2006). This part of the survey has been conducted with a very
limited nubmer of observations per star, and rough accuracy. We apply the
Monte-Carlo simulations to infer a fraction of the RV-stable stars in the
sample. Our optimistic estimate is that 20% of all considered K-giants have
RV-variability under 30 m s. Different assumptions of intrinsic
RV-variability for our stars give 12 -- 20 % of RV-stable K-giants in the
studied sample.Comment: 3 pages, 2 figures, to be published in PAS
WETLANDS AND ENDANGERED SPECIES: EDUCATIONAL ASSISTANCE NEEDS OF EXTENSION EDUCATORS
Environmental Economics and Policy,
Electrical futures past
Futurist writing about technology emerged in the late 19th century at the same time as new kinds of electrical technology were making utopian futures seem practically attainable. Electrical writers and novelists alike thus borrowed from the popular ‘science’ fiction of Jules Verne, Edward Bellamy and others to try to create self-fulfilling prophecies of a future in which electrical gadgets and machines met all major practical needs of civilization. To the extent that many parts of our world are populated by the hardware that they forecast, they succeeded in their goal
Mass-Radius Relations and Core-Envelope Decompositions of Super-Earths and Sub-Neptunes
Many exoplanets have been discovered with radii of 1-4 Earth radii, between
that of Earth and Neptune. A number of these are known to have densities
consistent with solid compositions, while others are "sub-Neptunes" likely to
have significant hydrogen-helium envelopes. Future surveys will no doubt
significantly expand these populations. In order to understand how the measured
masses and radii of such planets can inform their structures and compositions,
we construct models both for solid layered planets and for planets with solid
cores and gaseous envelopes, exploring a range of core masses, hydrogen-helium
envelope masses, and associated envelope entropies. For planets in the
super-Earth/sub-Neptune regime for which both radius and mass are measured, we
estimate how each is partitioned into a solid core and gaseous envelope,
associating a specific core mass and envelope mass with a given exoplanet. We
perform this decomposition for both "Earth-like" rock-iron cores and pure ice
cores, and find that the necessary gaseous envelope masses for this important
sub-class of exoplanets must range very widely from zero to many Earth masses,
even for a given core mass. This result bears importantly on exoplanet
formation and envelope evaporation processes.Comment: 26 pages, 21 figures, 16 tables, accepted to Ap
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