636 research outputs found
Model Checking One-clock Priced Timed Automata
We consider the model of priced (a.k.a. weighted) timed automata, an
extension of timed automata with cost information on both locations and
transitions, and we study various model-checking problems for that model based
on extensions of classical temporal logics with cost constraints on modalities.
We prove that, under the assumption that the model has only one clock,
model-checking this class of models against the logic WCTL, CTL with
cost-constrained modalities, is PSPACE-complete (while it has been shown
undecidable as soon as the model has three clocks). We also prove that
model-checking WMTL, LTL with cost-constrained modalities, is decidable only if
there is a single clock in the model and a single stopwatch cost variable
(i.e., whose slopes lie in {0,1}).Comment: 28 page
Daily Hassles and Uplifts in Employed and Nonemployed Women
The purpose of this study was to assess daily hassles and uplifts in women employed full time, part time, and not employed. From three pools of 100 names in each employment category, 90 subjects were randomly selected. Questionnaires related to daily hassles and uplifts and perceived stress and health were mailed to subjects and 83% of the questionnaires were returned. The resultant sample of 74 subjects was comprised of 24 full-time, 25 part-time, and 25 nonemployed women.
The means for hassles frequency, 21.52 ( = 13.20), and intensity, 1.44 ( ÂŁD = 0.32), indicated that subjects\u27 hassles were low and mild. Means for uplifts frequency, 52.95 ( SD = 24.36), and intensity, 1.85 ( SO = 0.36), showed that uplifts were moderate in number and severity. The most commonly identified hassle was a concern about weight and the uplift was visiting, phoning, or writing someone.
A one-way ANOVA showed that women employed full time perceived their stress as higher than the other two groups ( F j 2,71 ] = 7.16, q \u3c .001).
Health was perceived as good and was the same for all three groups of women in this study. A significant correlation between uplifts intensity and health was found ( 1 = .23, ÂŁ \u3c .05). Findings from this study could be used by nurses in planning women\u27s health maintenance programs and for identification of women at risk for illness
Average-energy games
Two-player quantitative zero-sum games provide a natural framework to
synthesize controllers with performance guarantees for reactive systems within
an uncontrollable environment. Classical settings include mean-payoff games,
where the objective is to optimize the long-run average gain per action, and
energy games, where the system has to avoid running out of energy.
We study average-energy games, where the goal is to optimize the long-run
average of the accumulated energy. We show that this objective arises naturally
in several applications, and that it yields interesting connections with
previous concepts in the literature. We prove that deciding the winner in such
games is in NP inter coNP and at least as hard as solving mean-payoff games,
and we establish that memoryless strategies suffice to win. We also consider
the case where the system has to minimize the average-energy while maintaining
the accumulated energy within predefined bounds at all times: this corresponds
to operating with a finite-capacity storage for energy. We give results for
one-player and two-player games, and establish complexity bounds and memory
requirements.Comment: In Proceedings GandALF 2015, arXiv:1509.0685
Intrinsic alignment contamination to CMB lensing-galaxy weak lensing correlations from tidal torquing
Correlations of galaxy ellipticities with large-scale structure, due to
galactic tidal interactions, provide a potentially significant contaminant to
measurements of cosmic shear. However, these intrinsic alignments are still
poorly understood for galaxies at the redshifts typically used in cosmic shear
analyses. For spiral galaxies, it is thought that tidal torquing is significant
in determining alignments resulting in zero correlation between the intrinsic
ellipticity and the gravitational potential in linear theory. Here, we
calculate the leading-order correction to this result in the tidal-torque model
from non-linear evolution, using second-order perturbation theory, and relate
this to the contamination from intrinsic alignments to the recently-measured
cross-correlation between galaxy ellipticities and the CMB lensing potential.
On the scales relevant for CMB lensing observations, the squeezed limit of the
gravitational bispectrum dominates the correlation. Physically, the large-scale
mode that sources CMB lensing modulates the small-scale power and hence the
intrinsic ellipticity, due to non-linear evolution. We find that the angular
cross-correlation from tidal torquing has a very similar scale dependence as in
the linear alignment model, believed to be appropriate for elliptical galaxies.
The amplitude of the cross-correlation is predicted to depend strongly on the
formation redshift, being smaller for galaxies that formed at higher redshift
when the bispectrum of the gravitational potential was smaller. Finally, we
make simple forecasts for constraints on intrinsic alignments from the
correlation of forthcoming cosmic shear measurements with current CMB lensing
measurements. We note that cosmic variance can be significantly reduced in
measurements of the difference in the intrinsic alignments for elliptical and
spiral galaxies if these can be separated (e.g., using colour).Royal Society of New ZealandâRutherford Foundation Trust; Cambridge Commonwealth Trust.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw164
Perceptions and practices of physical activity among columbian overweight/obese schoolchildren
The purpose of this study was to explore the contexts that shape obese childrenâs engagement in physical activity (PA) focusing on childrenâs perceptions. The qualitative design consisted of non-participant observations, and unstructured and semi-structured focus group and individual interviews. Data were analyzed by use of conventional content analysis. Participants were overweight/obese children from a public school in Colombia. The findings show that the main context where PA took place was during physical education (PE) classes at school and in the childrenâs neighborhoods. The participants perceived the PE classes to be too competitive and demotivating. PA taking place outside school was associated with fun, but occurred only on an infrequent basis and was challenged by living in insecure neighborhoods. Adapting a health promotion approach that emphasizes participation and social environments might motivate obese children to become physically active at school as well as during leisure time
Enhancement of thermoelectric properties by energy filtering: Theoretical potential and experimental reality in nanostructured ZnSb
Energy filtering has been suggested by many authors as a means to improve
thermoelectric properties. The idea is to filter away low-energy charge
carriers in order to increase Seebeck coefficient without compromising
electronic conductivity. This concept was investigated in the present paper for
a specific material (ZnSb) by a combination of first-principles atomic-scale
calculations, Boltzmann transport theory, and experimental studies of the same
system. The potential of filtering in this material was first quantified, and
it was as an example found that the power factor could be enhanced by an order
of magnitude when the filter barrier height was 0.5~eV. Measured values of the
Hall carrier concentration in bulk ZnSb were then used to calibrate the
transport calculations, and nanostructured ZnSb with average grain size around
70~nm was processed to achieve filtering as suggested previously in the
literature. Various scattering mechanisms were employed in the transport
calculations and compared with the measured transport properties in
nanostructured ZnSb as a function of temperature. Reasonable correspondence
between theory and experiment could be achieved when a combination of constant
lifetime scattering and energy filtering with a 0.25~eV barrier was employed.
However, the difference between bulk and nanostructured samples was not
sufficient to justify the introduction of an energy filtering mechanism. The
reasons for this and possibilities to achieve filtering were discussed in the
paper
Optimal infinite scheduling for multi-priced timed automata
This paper is concerned with the derivation of infinite schedules for timed automata that are in some sense optimal. To cover a wide class of optimality criteria we start out by introducing an extension of the (priced) timed automata model that includes both costs and rewards as separate modelling features. A precise definition is then given of what constitutes optimal infinite behaviours for this class of models. We subsequently show that the derivation of optimal non-terminating schedules for such double-priced timed automata is computable. This is done by a reduction of the problem to the determination of optimal mean-cycles in finite graphs with weighted edges. This reduction is obtained by introducing the so-called corner-point abstraction, a powerful abstraction technique of which we show that it preserves optimal schedules
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