24,980 research outputs found
Satisfiability of CTL* with constraints
We show that satisfiability for CTL* with equality-, order-, and
modulo-constraints over Z is decidable. Previously, decidability was only known
for certain fragments of CTL*, e.g., the existential and positive fragments and
EF.Comment: To appear at Concur 201
Dimension Spectra of Lines
This paper investigates the algorithmic dimension spectra of lines in the
Euclidean plane. Given any line L with slope a and vertical intercept b, the
dimension spectrum sp(L) is the set of all effective Hausdorff dimensions of
individual points on L. We draw on Kolmogorov complexity and geometrical
arguments to show that if the effective Hausdorff dimension dim(a, b) is equal
to the effective packing dimension Dim(a, b), then sp(L) contains a unit
interval. We also show that, if the dimension dim(a, b) is at least one, then
sp(L) is infinite. Together with previous work, this implies that the dimension
spectrum of any line is infinite
Long-term EXOTIME photometry and follow-up spectroscopy of the sdB pulsator HS 0702+6043
Pulsating subdwarf B (sdB) stars oscillate in short-period p-modes or
long-period g-modes. HS0702+6043 (DW Lyn) is one of a few objects to show
characteristics of both types and is hence classified as hybrid pulsator. It is
one of our targets in the EXOTIME program to search for planetary companions
around extreme horizontal branch objects. In addition to the standard exercise
in asteroseismology to probe the instantaneous inner structure of a star,
measured changes in the pulsation frequencies as derived from an O-C diagram
can be compared to theoretical evolutionary timescales. Based on the
photometric data available so far, we are able to derive a high-resolution
frequency spectrum and to report on our efforts to construct a multi-season O-C
diagram. Additionally, we have gathered time-resolved spectroscopic data in
order to constrain stellar parameters and to derive mode parameters as well as
radial and rotational velocities.Comment: 2 pages, JENAM 2008 proceedings, to be published in 'Communications
in Asteroseismology', 15
Experiments in monthly mean simulation of the atmosphere with a coarse-mesh general circulation model
The Hansen atmospheric model was used to compute five monthly forecasts (October 1976 through February 1977). The comparison is based on an energetics analysis, meridional and vertical profiles, error statistics, and prognostic and observed mean maps. The monthly mean model simulations suffer from several defects. There is, in general, no skill in the simulation of the monthly mean sea-level pressure field, and only marginal skill is indicated for the 850 mb temperatures and 500 mb heights. The coarse-mesh model appears to generate a less satisfactory monthly mean simulation than the finer mesh GISS model
Simulations of the monthly mean atmosphere for February 1976 with the GISS model
Monthly mean simulations of the global atmosphere were computed for February 1976 with the GISS model from observed initial conditions. In a replication experiment, two of these computations generated slightly different monthly mean states, apparently due to the schedule of interruptions on the computer. The root-mean-square errors of replication over the Northern Hemisphere were found to be about 2 mb, 20 m, and 1 K for sea-level pressure, 500 mb height, and 850 mb temperature, respectively. The monthly mean 500 mb forecast results for February 1976 over the Northern Hemisphere were consistent with those from earlier GISS model experiments
Micelle Formation and the Hydrophobic Effect
The tendency of amphiphilic molecules to form micelles in aqueous solution is
a consequence of the hydrophobic effect. The fundamental difference between
micelle assembly and macroscopic phase separation is the stoichiometric
constraint that frustrates the demixing of polar and hydrophobic groups. We
present a theory for micelle assembly that combines the account of this
constraint with a description of the hydrophobic driving force. The latter
arises from the length scale dependence of aqueous solvation. The theoretical
predictions for temperature dependence and surfactant chain length dependence
of critical micelle concentrations for nonionic surfactants agree favorably
with experiment.Comment: Accepted for publication in J. Phys. Chem.
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