8,990 research outputs found
Machine Learning Approaches for Region-level Prescription Demand Forecasting
Region-level prescription demand is closely intertwined with the incidence of diseases within a given area. However, conventional forecasting methods primarily rely on historical data, and ignore the spatial correlation in prescription data. In this study, we employ graph structures to capture the interactions among drug demand in different regions. By leveraging two popular graph neural network-based models, our objective is to harness the power of spatial-temporal correlation to enhance the accuracy of predictions. To assess the effectiveness of the graph neural network-based model, we conduct extensive experiments on a comprehensive real world dataset. The results demonstrate that the performance of the graph neural network consistently surpasses that of statistical learning-based methods and traditional deep learning-based methods.</p
Modeling the black holes surrounded by a dark matter halo in the galactic center of M87
In this paper, the structure of a dark matter halo can be well described by
the mass model of M87 and the Einasto profile for the cold dark matter model,
i.e., (Wang et al. in Nature 585:39-42, 2020). Under
these conditions, we construct a solution of a static spherically symmetric
black hole in a dark matter halo. Then, using the Newman-janis algorithm, we
extend this static solution to the case of rotation, and obtain a solution for
the Kerr-like black hole. We prove that this solution of the Kerr-like black
hole is indeed a solution to the Einstein field equations. Finally, taking M87
as an example, we study and analyze some physical properties of this Kerr-like
black hole, and then compare them with the Kerr black hole. Particularly, from
the perspective of the black hole shadow and the fact that the Kerr-like black
hole and the Kerr black hole is distinguishable, we give the upper limit of the
shape parameter of the Einasto density profile, that is approximately
, which may provide a new method to further improve and perfect
the density profile of dark matter model. These research results for the black
hole in a dark matter halo may indirectly provide an effective method for
detecting the existence of dark matter
Echoes from black bounces surrounded by the string cloud
In the string theory, the fundamental blocks of nature are not particles but
one-dimensional strings. Therefore, a generalization of this idea is to think
of it as a cloud of strings. Rodrigues et al. embedded the black bounces
spacetime into the string cloud, which demonstrates that the existence of the
string cloud makes the Bardeen black hole singular, while the black bounces
spacetime remains regular. On the other hand, the echoes are the correction to
the late stage of the quasinormal ringing for a black hole, which is caused by
the deviation of the spacetime relative to the initial black hole spacetime
geometry in the near-horizon region. In this work, we study the gravitational
wave echoes of black bounces spacetime surrounded by a cloud of strings under
scalar field and electromagnetic field perturbation to explore what
gravitational effects near-horizon region are caused by string cloud. The
ringing of the regular black hole and traversable wormhole with string cloud
are presented. Our results demonstrate that the black bounce spacetime with
strings cloud is characterized by gravitational wave echoes as it transitions
from regular black holes to wormholes, i.e. the echoes signal will facilitate
us to distinguish between black holes and the wormholes in black bounces
surrounded by the string cloud
Probing hairy black holes caused by gravitational decoupling using quasinormal modes, and greybody bounds
Extended gravitational decoupling can add hair to the black holes in general
relativity by adding extra sources. The quasinormal modes of hairy black holes
caused by gravitational decoupling for the massless scalar field,
electromagnetic field, and axial gravitational perturbation are investigated.
The equation of effective potential for three perturbations is derived in hairy
black holes spacetime. We also study the time evolution corresponding to the
three perturbations, and the quasinormal mode frequencies are calculated using
the Prony method through the time-domain profiles. Particularly, we find that
the response of hairy black hole spacetime to axial gravitational perturbations
is completely different from scalar field and electromagnetic field
perturbations, which may be due to the fact that the gravitational radiation
produced by the perturbations of the hairy black hole metric itself is much
stronger than that of the external field. Furthermore, we have calculated the
bounds on this greybody factor and high-energy absorption cross section with
the Sinc approximation. The study reveals that the charges ( and )
generating primary hair contributes positively to the greybody bounds and
absorption cross section, whereas the tidal charge from the extra sources
does the opposite
Construction of a dense genetic linkage map and mapping quantitative trait loci for economic traits of a doubled haploid population of Pyropia haitanensis (Bangiales, Rhodophyta)
The genotypes of 4550 LP markers that were mapped onto the genetic map. (XLSX 1645 kb
COMPARISON OF BRAIN METABOLITE CHANGES IN MANGANESE-EXPOSED WELDERS AND SMELTERS
poster abstractExcessive manganese (Mn) exposure is known to cause cognitive, psychiatric and motor deficits. Mn overexposure occurs in different occupational settings, where the type and level of exposure may vary. Magnetic resonance imaging (MRI) and spectroscopy (MRS) can be used to evaluate brain Mn accumulation and to measure Mn-induced metabolite changes non-invasively. The aim of this study was to compare metabolite changes among different brain regions of welders and smelters following occupational Mn exposure. Nine Mn-exposed smelters, 14 Mn-exposed welders and 23 male matched controls were recruited from a cohort of workers from two factories in China (mean airborne Mn level: 0.227 and 0.025 mg/m3 for smelters and welders, respectively). Short-echo-time 1H MRS spectra were acquired in each subject from four volumes of interest: the frontal cortex, posterior cingulate cortex, hippocampus, and thalamus. We found that 1) in the frontal cortex, significantly decreased creatine (Cr), glutamate (Glu) and glutathione (GSH) were found in welders, whereas decreased Glu was found in smelters as compared to controls. 2) In the thalamus, reduced myo-inositol was found in both smelters and welders, while Glu and GSH were decreased in welders. These results suggest that Mn-induced brain metabolite changes may be regional in nature and more extensive in welders than in smelters. The frontal cortex seems to show a more profound change than the other brain areas tested among Mn exposed subjects. Further studies are needed to investigate the effects of exposure type and length on the mechanism of Mn neurotoxicity. (Supported by NIH/NIEHS R21 ES-017498, National Science Foundation of China Grant #81072320 and 30760210)
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