4,445 research outputs found
A New Comparative Definition of Community and Corresponding Identifying Algorithm
In this paper, a new comparative definition for community in networks is
proposed and the corresponding detecting algorithm is given. A community is
defined as a set of nodes, which satisfy that each node's degree inside the
community should not be smaller than the node's degree toward any other
community. In the algorithm, the attractive force of a community to a node is
defined as the connections between them. Then employing attractive force based
self-organizing process, without any extra parameter, the best communities can
be detected. Several artificial and real-world networks, including Zachary
Karate club network and College football network are analyzed. The algorithm
works well in detecting communities and it also gives a nice description for
network division and group formation.Comment: 11 pages, 4 fihure
Kinematics of the Broad-line Region of 3C 273 from a Ten-year Reverberation Mapping Campaign
Despite many decades of study, the kinematics of the broad-line region of
3C~273 are still poorly understood. We report a new, high signal-to-noise,
reverberation mapping campaign carried out from November 2008 to March 2018
that allows the determination of time lags between emission lines and the
variable continuum with high precision. The time lag of variations in H
relative to those of the 5100 Angstrom continuum is days
in the rest frame, which agrees very well with the Paschen- region
measured by the GRAVITY at The Very Large Telescope Interferometer. The time
lag of the H emission line is found to be nearly the same as for
H. The lag of the Fe II emission is days, longer
by a factor of 2 than that of the Balmer lines. The velocity-resolved lag
measurements of the H line show a complex structure which can be
possibly explained by a rotation-dominated disk with some inflowing radial
velocity in the H-emitting region. Taking the virial factor of , we derive a BH mass of and an accretion rate of from the
H line. The decomposition of its images yields a host stellar mass
of , and a ratio of in agreement with the Magorrian relation. In the near
future, it is expected to compare the geometrically-thick BLR discovered by the
GRAVITY in 3C 273 with its spatially-resolved torus in order to understand the
potential connection between the BLR and the torus.Comment: 17 pages, 12 figures, 6 tables, accepted for publication in The
Astrophysical Journa
Quantum phase transition in the Frenkel-Kontorova chain: from pinned instanton glass to sliding phonon gas
We study analytically and numerically the one-dimensional quantum
Frenkel-Kontorova chain in the regime when the classical model is located in
the pinned phase characterized by the gaped phonon excitations and devil's
staircase. By extensive quantum Monte Carlo simulations we show that for the
effective Planck constant smaller than the critical value the
quantum chain is in the pinned instanton glass phase. In this phase the
elementary excitations have two branches: phonons, separated from zero energy
by a finite gap, and instantons which have an exponentially small excitation
energy. At the quantum phase transition takes place and for
the pinned instanton glass is transformed into the sliding
phonon gas with gapless phonon excitations. This transition is accompanied by
the divergence of the spatial correlation length and appearence of sliding
modes at .Comment: revtex 16 pages, 18 figure
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A First Step Towards Behavioral Coaching for Managing Stress: A Case Study on Optimal Policy Estimation with Multi-stage Threshold Q-learning
Psychological stress is a major contributor to the adoption of unhealthy behaviors, which in turn accounts for 41% of global cardiovascular disease burden. While the proliferation of mobile health apps has offered promise to stress management, these apps do not provide micro-level feedback with regard to how to adjust one's behaviors to achieve a desired health outcome. In this paper, we formulate the task of multi-stage stress management as a sequential decision-making problem and explore the application of reinforcement learning to provide micro-level feedback for stress reduction. Specifically, we incorporate a multi-stage threshold selection into Q-learning to derive an interpretable form of a recommendation policy for behavioral coaching. We apply this method on an observational dataset that contains Fitbit ActiGraph measurements and self-reported stress levels. The estimated policy is then used to understand how exercise patterns may affect users' psychological stress levels and to perform coaching more effectively
Inequalities in Cervical Cancer Screening Uptake Between Chinese Migrant Women and Local Women: A Cross-Sectional Study
Introduction:
Uptake of cervical cancer screening services in Chinese migrant workers is unknown and may be lower than non-migrant workers in China.
Methods:
We conducted a cross-sectional study among migrant and non-migrant women aged 21-65 at 7 provinces across China and administered a questionnaire investigating knowledge and attitudes regarding cervical cancer, human papillomavirus (HPV), and HPV vaccine. We used multivariable logistic regression to evaluate odds of previous cervical cancer screening in migrant workers.
Results:
737 women participated in the study. Mean age was 41.9 ± 7.2 years. 50.2% of the participants were migrant workers. 27.6% of the migrant workers reported previous cervical cancer screening compared to 33.2% of local participants. 36.6% migrant workers reported awareness of HPV compared to 40.2% of local participants. In adjusted analysis migrant status was not associated with increased odds of previous cervical cancer screening (aOR = 1.11 95%CI: 0.76-1.60). High school or higher education compared to less than high school education and employer-sponsored insurance compared to uninsured were associated with increased odds of previous cervical cancer screening (aOR = 2.15 95%CI: 1.41-3.27 and aOR = 1.67 95% CI: 1.14-2.45, respectively). Having heard of HPV compared to no awareness of HPV was associated with increased odds of cervical cancer screening (aOR = 2.02 95%CI: 1.41-2.91). Awareness of HPV among migrant workers was associated with increased odds of cervical cancer screening compared to migrant and local participants without awareness (aOR = 2.82 95% CI: 1.70-4.69 and 2.97 95%CI: 1.51-5.83, respectively).
Conclusions:
Efforts to increase education opportunities, provide insurance, and promote HPV awareness could increase cervical cancer screening uptake in migrant women in China
Combination of selenium and green tea improves the efficacy of chemoprevention in a rat colorectal cancer model by modulating genetic and epigenetic biomarkers
Dietary supplementation of selenium and green tea holds promise in cancer prevention. In this study, we evaluated the
efficacies of selenium and green tea administered individually and in combination against colorectal cancer in an
azoxymethane (AOM)-induced rat colonic carcinogenesis model and determined the underlying mechanisms of the
protection. Four-week old Sprague-Dawley male rats were fed with diets containing 0.5% green tea extract, 1ppm selenium
as selenium-enriched milk protein, or combination of 1ppm selenium and 0.5% green tea extract. Animals received 2 AOM
(15 mg/kg) treatments to induce colonic oncogenesis. Rats were killed 8 or 30 wk later after the last AOM to examine the
effect of dietary intervention on aberrant crypt foci (ACF) formation or tumor development. On sacrifice, colons were
examined for ACF and tumors, the mRNA levels of SFRP5 and Cyclin D1, and the proteins levels of ß-catenin, COX-2, Ki-67,
DNMT1 and acetyl histone H3. The combination of selenium and green tea resulted in a significant additive inhibition of
large ACF formation, this effect was greater than either selenium or green tea alone, P,0.01; the combination also had a
significant additive inhibition effect on all tumor endpoints, the effect of the combination diet on tumor incidence,
multiplicity and size was greater than selenium or green tea alone, P,0.01. Rats fed the combination diet showed marked
reduction of DNMT1 expression and induction of histone H3 acetylation, which were accompanied by restoration of SFRP5
mRNA in normal-appearing colonic crypts. The combination diet also significantly reduced ß-catenin nuclear translocation,
Cyclin D1 expression and cell proliferation. These data show, for the first time, that combination of selenium and green tea is
more effective in suppressing colorectal oncogenesis than either agent alone. The preventive effect is associated with
regulation of genetic and epigenetic biomarkers implicated in colonic carcinogenesis
Fully Band Resolved Scattering Rate in MgB2 Revealed by Nonlinear Hall Effect and Magnetoresistance Measurements
We have measured the normal state temperature dependence of the Hall effect
and magnetoresistance in epitaxial MgB2 thin films with variable disorders
characterized by the residual resistance ratio RRR ranging from 4.0 to 33.3. A
strong nonlinearity of the Hall effect and magnetoresistance have been found in
clean samples, and they decrease gradually with the increase of disorders or
temperature. By fitting the data to the theoretical model based on the
Boltzmann equation and ab initio calculations for a four-band system, for the
first time, we derived the scattering rates of these four bands at different
temperatures and magnitude of disorders. Our method provides a unique way to
derive these important parameters in multiband systems.Comment: 4 pages, 4 figure
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