15,671 research outputs found
Hard X-ray emission cutoff in anomalous X-ray pulsar 4U 0142+61 detected by INTEGRAL
The anomalous X-ray pulsar 4U 0142+61 was studied by the INTEGRAL
observations. The hard X-ray spectrum of 18 -- 500 keV for 4U 0142+61 was
derived using near 9 years of INTEGRAL/IBIS data. We obtained the average hard
X-ray spectrum of 4U 0142+61 with all available data. The spectrum of 4U
0142+61 can be fitted with a power-law with an exponential high energy cutoff.
This average spectrum is well fitted with a power-law of plus a cutoff energy at keV. The hard X-ray flux of the
source from 20 -- 150 keV showed no significant variations (within 20) from
2003 -- 2011. The spectral profiles have some variability in nine years: photon
index varied from 0.3 -- 1.5, and cutoff energies of 110 -- 250 keV. The
detection of the high energy cutoff around 130 keV shows some constraints on
the radiation mechanisms of magnetars and possibly probes the differences
between magnetar and accretion models for these special class of neutron stars.
Future HXMT observations could provide stronger constraints on the hard X-ray
spectral properties of this source and other magnetar candidates.Comment: 9 pages, 5 figures, 2 tables, figures are updated, new data are
added, conclusion does not change, to be published in RA
Complexity growth rates for AdS black holes in massive gravity and gravity
The "complexity = action" duality states that the quantum complexity is equal
to the action of the stationary AdS black holes within the Wheeler-DeWitt patch
at late time approximation. We compute the action growth rates of the neutral
and charged black holes in massive gravity and the neutral, charged and
Kerr-Newman black holes in gravity to test this conjecture. Besides, we
investigate the effects of the massive graviton terms, higher derivative terms
and the topology of the black hole horizon on the complexity growth rate.Comment: 11 pages, no figur
Adjusting inverse regression for predictors with clustered distribution
A major family of sufficient dimension reduction (SDR) methods, called
inverse regression, commonly require the distribution of the predictor to
have a linear and a degenerate
for the desired reduced predictor
. In this paper, we adjust the first and second-order
inverse regression methods by modeling and
under the mixture model assumption on ,
which allows these terms to convey more complex patterns and is most suitable
when has a clustered sample distribution. The proposed SDR methods build a
natural path between inverse regression and the localized SDR methods, and in
particular inherit the advantages of both; that is, they are
-consistent, efficiently implementable, directly adjustable under the
high-dimensional settings, and fully recovering the desired reduced predictor.
These findings are illustrated by simulation studies and a real data example at
the end, which also suggest the effectiveness of the proposed methods for
nonclustered data
Effects of Dynamic Icons on the Perceived Usability in the Travel App
With the advancements in hardware and information technology, the use of dynamic icons in travel app interfaces to convey information has become increasingly common. The goal is to provide users with a novel experience that was not available in the static interfaces of the past. However, it remains unclear whether the availability and utilization of dynamic icons actually enhance the usability of apps and if it is done with genuine consideration for users\u27 benefit. This study aims to investigate how users perceive and use dynamic icons in the context of human-computer interaction, using a travel app as the research object. We propose a user-centered subjective and objective hybrid evaluation methodology to examine the perceived usability of dynamic icons, taking into account different evaluation characteristics at various usability levels. Our results indicate no significant statistical difference between the perceived usability of dynamic icons and static icons. We employed two indicators, perceived ease and subjective priority, to evaluate the perceived usability of dynamic icons. The findings show that the perceived ease of dynamic icons is higher than that of static icons, with an increase of 3.72% (I) and 3.09% (II) in respective studies, but with a reduction of 13.19% compared to static icons in study III. We conclude that although the perceived usability of dynamic icons may not be significantly different from static icons, they exhibit higher objective usability in users\u27 decision-making behavior
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