781 research outputs found
Measuring mass transfer of AM CVn binaries with a space-based gravitational wave detector
The formation mechanism of AM CVn binary has not been well understood yet.
Accurate measurements of the mass transfer rate can help to determine the
formation mechanism. But unfortunately such observation by electromagnetic
means is quite challenging. One possible formation channel of AM CVn binary is
a semi-detached white dwarf binary. Such system emits strong gravitational wave
radiation which could be measured by the future space-based detectors. We can
simultaneously extract the mass transfer rate and the orbital period from the
gravitational wave signal. We employ a post-Keperian waveform model of
gravitational wave and carry out a Fisher analysis to estimate the measurement
accuracy of mass transfer rate through gravitational wave detection. Special
attention is paid to the observed sources in Gaia Data Release 2. We found that
we can accurately measure the mass transfer rate for those systems. Comparing
to electromagnetic observations, gravitational wave detection improves the
accuracy more than one order. Our results imply that the gravitational wave
detection will help much in understanding the formation mechanism of AM CVn
binaries
A new classification system of lithic-rich tight sandstone and its application to diagnosis high-quality reservoirs
Lithic-rich tight sandstone is one of the most enrichment lithofacies in the Sulige gas field. Clarifying the enrichment mechanism of high-quality lithic-rich tight sandstone is important to economic and efficient development of the tight gas reservoir. This paper introduces a new classification method, which is based on the origin of particles and interstitial materials and their control on reservoir pores growth. Lithic-rich tight sandstone can be subdivided into three types: sedimentary lithic sandstone, diagenetic lithic sandstone and event-type lithic sandstone. The genetic mechanism of a high-quality reservoir is studied by this new method. Research shows that the sedimentary lithic sandstone has high contents of plastic lithics, strong compaction effects of early diagenesis, large porosity reduction and almost no dissolution-induced porosity. The diagenetic lithic sandstone has high contents of rigid lithics and strong compaction effects. Organic acids promote alteration of a large amount of feldspars into kaolinite, while such sandstones are highly cemented. It is seen with moderate porosity reduction and moderate dissolution-attributed porosity growth. Event-type lithic sandstone also has high contents of rigid debris and strong compaction effects. Synsedimentary volcanic dust materials of subaerial deposition are altered into illite through smectite and illite-smectite mixed-layer clay under the effects of acids, which generate many pores and results in large dissolution-attributed porosity growth. Research shows that the sedimentary lithic sandstone has poor physical properties and is identified as the unfavorable reservoir; the diagenetic lithic sandstone having medium physical properties, as the relatively favorable reservoir; the event-type lithic sandstone having good physical properties, as the favorable reservoir. The research route and results have laid a solid geological foundation for better development of lithic-rich tight sandstone reservoirs.Cited as: Liu, Y., Xian, C., Li, Z., Wang, J., Ren, F. A new classification system of lithic-rich tight sandstone and its application to diagnosis high-quality reservoirs. Advances in Geo-Energy Research, 2020, 4(3): 286-295, doi: 10.46690/ager.2020.03.0
BiSyn-GAT+: Bi-Syntax Aware Graph Attention Network for Aspect-based Sentiment Analysis
Aspect-based sentiment analysis (ABSA) is a fine-grained sentiment analysis
task that aims to align aspects and corresponding sentiments for
aspect-specific sentiment polarity inference. It is challenging because a
sentence may contain multiple aspects or complicated (e.g., conditional,
coordinating, or adversative) relations. Recently, exploiting dependency syntax
information with graph neural networks has been the most popular trend. Despite
its success, methods that heavily rely on the dependency tree pose challenges
in accurately modeling the alignment of the aspects and their words indicative
of sentiment, since the dependency tree may provide noisy signals of unrelated
associations (e.g., the "conj" relation between "great" and "dreadful" in
Figure 2). In this paper, to alleviate this problem, we propose a Bi-Syntax
aware Graph Attention Network (BiSyn-GAT+). Specifically, BiSyn-GAT+ fully
exploits the syntax information (e.g., phrase segmentation and hierarchical
structure) of the constituent tree of a sentence to model the sentiment-aware
context of every single aspect (called intra-context) and the sentiment
relations across aspects (called inter-context) for learning. Experiments on
four benchmark datasets demonstrate that BiSyn-GAT+ outperforms the
state-of-the-art methods consistently
Development and application of the Chinese version of the adult strabismus quality of life questionnaire (AS-20): a cross-sectional study
Abstract
Background
Patients with strabismus experience visual dysfunction, self-image disorders, low self-esteem, and social and emotional barriers, which adversely influence their health-related quality of life (HRQoL). Currently no strabismus-specific questionnaire is available in China to identify patients’ quality of life and to evaluate the effectiveness of strabismus treatment. The aims of the present study were to validate the Chinese-language version of the Adult Strabismus Quality of Life Questionnaire (AS-20) and to evaluate the impacts of strabismus on the quality of life among Chinese strabismus patients.
Methods
Two hundred and fifty-five Chinese adults with strabismus, one hundred visually normal adults and one hundred patients with other eye diseases completed the Chinese version of AS-20. Psychometric properties of the Chinese AS-20 were examined by Cronbach’s α coefficient, test-retest and split-half reliability, and construct and criterion-related validity. Independent-samples t test and one-way ANOVA analyses were conducted to explore the impact of demographic factors and clinical characteristics on HRQoL in Chinese strabismic adults.
Results
The final AS-20 in Chinese (AS-C) included 18 items and two subscales: psychosocial (12 items) and function (6 items). The Cronbach’s α was 0.908 for overall scale, with 0.913 and 0.808 for \u27psychosocial’ and \u27function’ subscales respectively, indicating high internal consistency reliability. The mean of the overall AS-C score among strabismus patients was 62.80 ± 18.94, significantly lower than that in visually normal adults (t = -18.693, P \u3c 0.001), and in patients with other eye diseases (t = -5.512, P \u3c 0.001).
Conclusions
The AS-C is a culturally appropriate tool to evaluate the HRQoL in Chinese strabismus adults. The psychosocial health well-being and overall quality of life in strabismic patients should receive greater emphasis
EUCLIA - Exploring the UV/optical continuum lag in active galactic nuclei. I. a model without light echoing
The tight inter-band correlation and the lag-wavelength relation among
UV/optical continua of active galactic nuclei have been firmly established.
They are usually understood within the widespread reprocessing scenario,
however, the implied inter-band lags are generally too small. Furthermore, it
is challenged by new evidences, such as the X-ray reprocessing yields too much
high frequency UV/optical variations as well as it fails to reproduce the
observed timescale-dependent color variations among {\it Swift} lightcurves of
NGC 5548. In a different manner, we demonstrate that an upgraded inhomogeneous
accretion disk model, whose local {\it independent} temperature fluctuations
are subject to a speculated {\it common} large-scale temperature fluctuation,
can intrinsically generate the tight inter-band correlation and lag across
UV/optical, and be in nice agreement with several observational properties of
NGC 5548, including the timescale-dependent color variation. The emergent lag
is a result of the {\it differential regression capability} of local
temperature fluctuations when responding to the large-scale fluctuation. An
average speed of propagations as large as of the speed of light
may be required by this common fluctuation. Several potential physical
mechanisms for such propagations are discussed. Our interesting
phenomenological scenario may shed new light on comprehending the UV/optical
continuum variations of active galactic nuclei.Comment: 18 pages, 8 figures. ApJ accepted. Further comments are very welcome
An intrinsic link between long-term UV/optical variations and X-ray loudness in quasars
Observations have shown that UV/optical variation amplitude of quasars depend
on several physi- cal parameters including luminosity, Eddington ratio, and
likely also black hole mass. Identifying new factors which correlate with the
variation is essential to probe the underlying physical processes. Combining
~ten years long quasar light curves from SDSS stripe 82 and X-ray data from
Stripe 82X, we build a sample of X-ray detected quasars to investigate the
relation between UV/optical variation amplitude () and X-ray
loudness. We find that quasars with more intense X-ray radiation (com- pared to
bolometric luminosity) are more variable in UV/optical. Such correlation
remains highly significant after excluding the effect of other parameters
including luminosity, black hole mass, Ed- dington ratio, redshift, rest-frame
wavelength (i.e., through partial correlation analyses). We further find the
intrinsic link between X-ray loudness and UV/optical variation is gradually
more prominent on longer timescales (up to 10 years in the observed frame), but
tends to disappear at timescales < 100 days. This suggests a slow and long-term
underlying physical process. The X-ray reprocessing paradigm, in which
UV/optical variation is produced by a variable central X-ray emission
illuminating the accretion disk, is thus disfavored. The discovery points to an
interesting scheme that both the X-ray corona heating and UV/optical variation
is quasars are closely associated with magnetic disc turbulence, and the
innermost disc turbulence (where corona heating occurs) correlates with the
slow turbulence at larger radii (where UV/optical emission is produced).Comment: 9 pages, 4 figures, 1 table, accepted by Ap
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